행복에 대한 본질주의적 믿음이 웰빙에 미치는 영향

학위논문 (석사)-- 서울대학교 대학원 : 심리학과, 2015. 2. 최인철.Lay theories about happiness are pervasive in lay peoples everyday life. However, to date, despite lay peoples fascination with happiness, we know little about lay theories about happiness and its implications for well-being. The current research investigated lay theories about happiness within a framework of psychological essentialism. In Study 1 and 2, I developed and validated a new scale to assess the essentialist beliefs about happiness with three components: (1) the immutability, (2) the biological basis, and (3) the effort constructivism. In Study 3, I found that the essentialist beliefs about happiness were negatively correlated with well-being measures and with intention of happiness-seeking behaviors. To clarify the causal effect, in Study 4, I experimentally manipulated essentialist beliefs about happiness and revealed that viewing happiness in a perspective of essentialists significantly reduced intentions to engage in happiness exercises. In Study 5, a one-week intervention study was conducted to examine whether there exist moderating effects of the essentialist belief about happiness on the effectiveness of happiness-boosting interventions. The results showed that positive interventions yielded equal effectiveness. Implications for well-being are discussed.Abstract і Introduction 1 Study 1 10 Method 10 Results & Discussion 11 Study 2 15 Method 15 Results & Discussion 18 Study 3 23 Method 23 Results & Discussion 25 Study 4 29 Method 29 Results & Discussion 31 Study 5 37 Method 38 Results & Discussion 41 General Discussion 46Maste

중형기공성 니켈/알루미나 촉매 상에서 수증기 개질 반응을 통한 수소 생산

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 화학생물공학부, 2018. 2. 김도희.With increasing concerns about the depletion of fossil fuels and global warming, various researches on sustainable and renewable energy have attracted much attention. Hydrogen has been considered as one of the most advantageous energy carriers because of its high energy density, eco-friendliness, and abundance. Steam reforming of natural gas is the predominant means of producing hydrogen due to its high hydrogen conversion efficiency and excellent economical advantage. Nickel-based catalysts are known to show high activity in the steam reforming of natural gas. However, nickel-based catalysts retain weak resistance toward catalyst deactivation caused by nickel sintering and carbon deposition. Therefore, it is important to develop a new preparation method for nickel-based catalyst to achieve high catalytic activity and enhanced stability in the steam reforming of natural gas. In this work, in order to achieve efficient catalyst system for steam reforming of natural gas, mesoporous nickel/alumina catalysts were designed by various catalyst compositions such as the addition of alkaline earth metal and vanadium, and preparation methods such as a supercritical CO2 drying method and the use of butyric acid. First, A series of mesoporous alkaline earth metal-promoted nickel-alumina xerogel (M/NA, M = Mg, Ca, Sr, and Ba) catalysts were prepared by a single-step epoxide-driven sol-gel method and a subsequent incipient wetness impregnation method. For reference, a nickel-alumina xerogel catalyst without promoter (NA) was prepared by a single-step epoxide-driven sol-gel method. Hydrogen chemisorption analyses showed that nickel surface area of reduced catalysts decreased in the order of Mg/NA > Sr/NA > Ca/NA > NA > Ba/NA. In the hydrogen production by steam reforming of natural gas, the catalytic performance of NA and M/NA catalysts was well correlated with the nickel surface area of the catalystsnatural gas conversion and hydrogen yield increased with increasing nickel surface area. Among the catalysts tested, Mg/NA catalyst with the highest nickel surface area showed the best catalytic performance. The amount of carbon deposition on the used M/NA catalysts was less than that on the used NA catalyst. In order to improve the best catalyst Mg/NA above, magnesium-doped mesoporous nickel-alumina aerogel catalyst (Mg/NAA) was prepared by a single-step epoxide-driven sol-gel method and a subsequent supercritical CO2 drying followed by an incipient wetness impregnation method. For comparison, magnesium-doped mesoporous nickel-alumina xerogel catalyst (Mg/NAX) was prepared by the similar method of Mg/NA above. Surface area, pore volume, and average pore dimeter of Mg/NAA catalysts were larger than those of Mg/NAX catalyst due to suppressed collapse of nickel-alumina gel network during the drying step. Nickel surface area and nickel dispersion of reduced catalysts were better in Mg/NAA catalyst than in Mg/NAX catalyst. In the CH4-TPD analyses, CH4 affinity of Mg/NAA catalyst was higher than that of Mg/NAX catalyst. In the hydrogen production by steam reforming of natural gas, Mg/NAA catalyst with the higher nickel dispersion and high CH4 affinity showed the better catalytic performance than Mg/NAX catalyst in terms of natural gas conversion and hydrogen yield. Vanadium-nickel-alumina catalysts with different vanadium loading (xVNA, x = 0, 0.5, 1.0, 1.5, and 2.0) were prepared by a single-step sol-gel method. TPR analyses revealed that the addition of vanadium increased reducibility of xVNA catalysts. From XRD analyses of reduced xVNA catalysts, it was found that an appropriate amount of vanadium reduced nickel crystallite size. In the hydrogen production by steam reforming of natural gas, natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to vanadium loading. Among the catalysts, vanadium-nickel-alumina catalyst with 1.0 wt% vanadium, which retained the smallest crystallite size of metallic nickel, showed the best catalytic performance. A series of butyric acid (BA)-assisted nickel/alumina catalysts (denoted as xBAN/A) with different butyric acid/Ni molar ratio (x) were prepared by an impregnation method. xBAN/A catalysts with an appropriate amount of butyric acid showed the enhanced nickel dispersion because of steric hindrance of butyric acid shell surrounding nickel particle. Addition of butyric acid also increased methane adsorption capacity of the catalysts, which was directly related to the catalytic performance. In the steam reforming of natural gas, both natural gas conversion and hydrogen yield showed volcano-shaped trends with respect to butyric acid/Ni molar ratio (x). Natural gas conversion and hydrogen yield increased with increasing nickel dispersion. Among the catalysts tested, 0.25BAN/A catalyst with the highest nickel dispersion exhibited the best catalytic performance in the steam reforming of natural gas. In summary, various nickel/alumina catalysts were designed to produce hydrogen by steam reforming of natural gas. In order to investigate the effect of physicochemical properties of the catalysts on catalytic performance in the steam reforming of natural gas, several characterizations such as N2 adsorption-desorption, XRD, TPR, TEM, SEM, H2-TPD, CH4-TPD, and FT-IR analyses were conducted. It was concluded that nickel dispersion played a crucial role in determining the catalytic performance in the hydrogen production by steam reforming of natural gas.화석 연료의 고갈과 지구 온난화에 대한 우려가 커짐에 따라 지속 가능한 신재생 에너지에 대한 연구가 활발히 진행되고 있다. 여러 신재생 에너지 중에서도 수소는 에너지 밀도가 크고 환경 친화적이며 매장량이 풍부하기 때문에 가장 우수한 에너지 전달 매체 중의 하나로 각광을 받고 있다. 수소를 생산하는 방법으로는 에너지 전환율이 높고 경제성이 큰 천연가스의 수증기 개질 반응이 이용되고 있다. 천연가스의 수증기 개질 반응에는 니켈계 촉매가 높은 반응 활성을 나타낸다고 알려져 있다. 그러나 니켈계 촉매는 니켈 소결 및 탄소 침적에 의한 비활성화에 취약하다는 단점이 있다. 따라서 높은 반응 활성과 우수한 안정성을 갖는 신규 촉매를 개발하는 것이 매우 중요하다고 할 수 있다. 본 연구에서는 천연가스의 수증기 개질 반응에서 니켈/알루미나 촉매의 효율 향상을 위해 알칼리 토금속 첨가, 초임계 이산화탄소 건조법, 바나듐 첨가, 부티르 산을 이용한 함침법 등을 이용하였다. 우선, 단일공정 에폭사이드 유도 졸-겔법 및 초기습윤함침법으로 알칼리 토금속이 첨가된 중형기공성 니켈-알루미나 제로젤 (M/NA, M = Mg, Ca, Sr 및 Ba) 촉매를 제조하였다. 비교를 위해 알칼리 토금속이 첨가되지 않은 중형기공성 니켈-알루미나 제로젤 (NA) 촉매를 단일공정 에폭사이드 유도 졸-겔법으로 제조하였다. 수소 흡착 분석 결과 니켈 표면적은 Mg/NA > Sr/NA > Ca/NA > NA > Ba/NA의 순서로 감소하는 것을 확인할 수 있었다. NA 촉매와 M/NA 촉매를 천연가스의 수증기 개질 반응에 적용시킨 결과, 촉매 활성과 니켈 표면적이 양의 상관관계를 나타내는 것을 확인할 수 있었다. 제조된 촉매 중에서 니켈 표면적이 가장 넓은 Mg/NA가 가장 높은 반응 활성을 나타내었다. 반응 후 촉매의 탄소량 분석 결과 M/NA 촉매가 NA 촉매에 비해 탄소 침적이 적게 일어난 것을 확인하였다. 상기 촉매 중 가장 우수한 성능을 나타낸 Mg/NA 촉매를 더 개선하기 위해 단일공정 에폭사이드 유도 졸-겔법 및 초임계 이산화탄소 건조법과 초기습윤함침법을 이용하여 마그네슘이 첨가된 중형기공성 니켈-알루미나 에어로젤 (Mg/NAA) 촉매를 제조하였다. 비교를 위해 상기 Mg/NA 촉매와 유사한 방법으로 마그네슘이 첨가된 중형기공성 니켈-알루미나 제로젤 (Mg/NAX) 촉매를 제조하였다. 초임계 이산화탄소 건조법을 이용하여 제조된 Mg/NAA 촉매가 Mg/NAX 촉매에 비해 넓은 비표면적, 큰 기공 부피 및 기공 크기를 나타내었다. 이는 에어로젤의 건조 과정에서 니켈-알루미나 겔의 네트워크 구조가 붕괴되는 현상이 억제되었기 때문이라고 판단된다. 비표면적이 넓은 Mg/NAA 촉매는 Mg/NAX 촉매에 비해 넓은 니켈 표면적 및 높은 니켈 분산도를 나타내었다. 메탄 승온 탈착 분석 결과 Mg/NAA 촉매가 Mg/NAX 촉매에 비해 우수한 메탄 친화도를 보이는 것을 확인하였다. Mg/NAA 촉매와 Mg/NAX 촉매를 천연가스의 수증기 개질 반응에 적용시킨 결과 높은 니켈 분산도 및 메탄 친화도를 갖는 Mg/NAA 촉매가 더 높은 천연가스 전환율과 수소 수율을 나타내는 것을 확인할 수 있었다. 다양한 바나듐 담지량을 갖는 중형기공성 바나듐-니켈-알루미나 제조젤 (xVNA, x = 0, 0.5, 1.0, 1.5 및 2.0) 촉매를 단일공정 에폭사이드 유도 졸-겔법을 이용하여 제조하였다. TPR 분석 결과 바나듐이 첨가된 촉매에서 니켈 환원성이 향상된 것을 확인하였다. 환원된 촉매의 XRD 분석을 통해 적절한 양의 바나듐이 첨가되었을 경우 니켈 결정 크기가 작아지는 것을 확인할 수 있었다. xVNA 촉매를 천연가스의 수증기 개질 반응에 적용시킨 결과 천연가스 전환율과 수소 수율이 바나듐 담지량에 따라 화산형의 개형을 나타내었다. 제조된 촉매 중에서 1.0 wt%의 바나듐이 담지된 촉매가 가장 작은 니켈 결정 크기 및 가장 우수한 반응활성을 나타내었다. 함침 과정에서 다양한 부티르 산/니켈 몰 비(x)를 적용한 중형기공성 니켈/알루미나 제로젤 (xBAN/A) 촉매를 제조하였다. 함침 과정에서 적절한 양의 부티르 산이 첨가되었을 경우 니켈 입자를 둘러싼 부티르 산의 입체장애로 인해 니켈 분산도가 향상되는 것을 확인할 수 있었다. 적절한 양의 부티르 산이 첨가될 경우 촉매 반응 활성과 직접적인 관련성이 있는 메탄 흡착 능력 또한 향상되는 것을 확인하였다. 제조된 촉매를 천연가스의 수증기 개질 반응에 적용시킨 결과 반응 활성이 부티르 산/니켈 몰 비에 따라 화산형의 개형을 나타내었다. 제조된 촉매 중에서 0.25BAN/A 촉매가 가장 높은 니켈 분산도 및 반응활성을 나타내었다. 요약하면, 본 연구에서는 다양한 니켈/알루미나 촉매를 제조하여 천연가스의 수증기 개질 반응에 적용시켰다. 촉매의 물리화학적 특성이 천연가스의 수증기 개질 반응 활성에 미치는 영향을 설명하기 위해 질소 흡탈착, XRD, TPR, TEM, SEM, H2-TPD, CH4-TPD 및 FT-IR 등의 다양한 분석을 수행하였다. 결과적으로, 니켈의 분산도가 천연가스의 수증기 개질 반응을 통한 수소 생산에서 촉매 활성을 결정짓는 중요한 인자임을 확인하였다.Chapter 1. Introduction 1 1.1. Hydrogen energy 1 1.2. Steam reforming of natural gas 5 1.3. Objective 9 Chapter 2. Experimental 12 2.1. Preparation of catalysts 12 2.1.1. Preparation of mesoporous alkaline earth metal-doped nickel-alumina xerogel catalyst 12 2.1.2. Preparation of mesoporous nickel-alumina aerogel catalyst by a supercritical CO2 drying method 15 2.1.3. Preparation of mesoporous vanadium-nickel-alumina xerogel catalyst 18 2.1.4. Preparation of mesoporous nickel/alumina catalyst by a butyric acid-assisted impregnation method 20 2.2. Characterization 22 2.2.1. Physicochemical properties 22 2.2.2. Crystalline structure 22 2.2.3. Reducibility 22 2.2.4. Morphological feature 23 2.2.5. H2 and CH4 adsorption studies on reduced catalysts 23 2.2.6. Carbon deposition on used catalysts 25 2.2.7. Chemical states of elements 25 2.3. Hydrogen production by steam reforming of natural gas 26 Chapter 3. Results and Discussion 29 3.1. Mesoporous alkaline earth metal-doped nickel-alumina xerogel catalyst 29 3.1.1. Textural properties of calcined catalysts 29 3.1.2. Crystalline structures of calcined catalysts 32 3.1.3. Reducibility and metal-support interaction 34 3.1.4. Characterization of reduced catalysts 36 3.1.5. Catalytic performance in the steam reforming of natural gas 41 3.1.6. Characterization of used catalysts 45 3.2. Mesoporous nickel-alumina aerogel catalyst by a supercritical CO2 drying method 47 3.2.1. Textural properties of calcined catalysts 47 3.2.2. Crystalline structure of calcined catalysts 51 3.2.3. Reducibility and metal-support interaction 53 3.2.4. Characterization of reduced catalysts 55 3.2.5. Catalytic performance in the steam reforming of natural gas 63 3.3. Mesoporous vanadium-nickel-alumina xerogel catalyst 65 3.3.1. Textural properties of calcined catalysts 65 3.3.2. Crystalline structure of calcined catalysts 68 3.3.3. Reducibility and metal-support interaction 70 3.3.4. Characterization of reduced catalysts 73 3.3.5. Catalytic performance in the steam reforming of natural gas 76 3.4. Mesoporous nickel/alumina catalyst by a butyric acid-assisted impregnation method 81 3.4.1. Surface chemical state of as-prepared catalysts 81 3.4.2. Textural properties of calcined catalysts 84 3.4.3. Crystalline structure of calcined and reduced catalysts 87 3.4.4. Morphology of calcined and reduced catalysts 89 3.4.5. Reducibility and metal-support interaction 92 3.4.6. Characterization of reduced catalysts 94 3.4.7. Catalytic performance in the steam reforming of natural gas 101 Chapter 4. Conclusions 106 Bibliography 109 초 록 114Docto

Variable Breast Conditions: Comparison of Conventional and Real-time Compound Ultrasonography

OBJECTIVES: To illustrate and compare the appearances of variable breast conditions by conventional and real-time spatial compound images. METHODS: Cases illustrative of a broad range of breast conditions were collected. Each image pair consisted of conventional and real-time compound images with a stationary probe to maintain an identical projection. RESULTS: The various breast conditions, including normal anatomic structures and abnormal lesions, were evaluated and compared by conventional and real-time compound images. The real-time compound images revealed more realistic and clear images with reduced artifacts. CONCLUSIONS: Real-time compound images are superior to conventional images of normal and abnormal breast conditions. Real-time compound imaging is a good technique for evaluating the breast state.ope

Focal Fibrosis of the Breast Diagnosed by a Sonographically Guided Core Biopsy of Nonpalpable Lesions Imaging Findings and Clinical Relevance

OBJECTIVE: The purpose of this study was to evaluate the frequency of focal fibrosis of the breast diagnosed by a sonographically guided core biopsy of nonpalpable lesions, to characterize imaging features, and to evaluate their clinical relevance. METHODS: In a retrospective review of 724 lesions that underwent sonographically guided core biopsy of nonpalpable breast lesions, 62 cases had a diagnosis of focal fibrosis. Two radiologists analyzed the sonographic and mammographic findings according to the Breast Imaging Reporting and Data System. The results were compared with histologic findings at surgery or imaging findings during surveillance. RESULTS: The incidence of focal fibrosis was 8.6% (62/724). Sonographic films were available in 56 cases, so 56 cases were reviewed for their sonographic findings. Among the mammograms reviewed, 64.7% (33/51) had negative findings. Among the sonograms reviewed, the most common features were oval shape (32/56, 57.1%), parallel orientation (36/56, 64.3%), microlobulated margin (24/56, 42.9%), abrupt interface (50/56, 89.3%), isoechoic pattern (42/56, 75.0%), and a lack of posterior acoustic features (45/56, 80.4%). The Breast Imaging Reporting and Data System final assessment was category 3 in 27 (48.2%) and category 4 in 29 (51.8%). Most of the category 4 lesions were category 4A (26/29, 89.7%). Surgical excision (n = 7) and follow-up for at least 1 year (n = 49) showed no malignancy. CONCLUSIONS: Focal fibrosis was found in 8.6% by a sonographically guided core biopsy of nonpalpable breast lesions. Most of the lesions were categorized as probably benign (category 3) or having a low suggestion of malignancy (category 4A). Focal fibrosis diagnosed at core biopsy can be managed with a 6-month follow-up protocol.ope

초음파에서 악성이 의심되었던 고형 혹의 재 분석

Purpose: The objective of our study was to reconsider the usefulness of many characteristics on US for differentiating benign and malignant masses. Materials and Methods: From February 2000 through April 2001, we retrospectively evaluated 309 solid breast nodules (282 patients) on US, which were categorized suspicious malignancy or suggestive malignancy, prospectively and confirmed by core-needle biopsy or operation. We analyzed the solid nodules, according to eight known malignant characteristics, which have been described in Stavros et al’s study. The sensitivity, specificity, positive predictive value, negative predictive value and odds ratio were calculated. Results: Among 309 lesions diagnosed as suspicious or suggestive malignancy prospectively, 140 lesions (45.31 %) were confirmed as malignant nodules. The mean number of these findings per one nodule was 2.5 (benign nodule: 2.2, malignant nodule: 2.7). Spiculated margin, marked hypoechogenecity, shadowing, and punctate microcalcifications were statistically significant. Odds ratio of punctate calcifications is the highest (19.5), followed by marked hypoechogenecity (3.1), spiculated margin (1.9), spiculated, microlobulated or angular margin (1.7), taller than wide (1.2), additional findings (1), and shadowing (0.6). Conclusion: Ultrasonographic findings are useful to differentiate malignant from benign solid nodules by that of Stavros et al’s.ope

Hydrogen production by steam reforming of liquefied natural gas (LNG) over mesoporous nickel-alumina catalysts: Effect of alkaline earth metal addition

학위논문 (석사)-- 서울대학교 대학원 : 화학생물공학부, 2015. 2. 송인규.본 연구에서는 천연가스의 수증기 개질 반응을 통해 수소를 생산하기 위한 촉매 연구를 수행하였다. 먼저 천연가스의 수증기 개질 반응에 적용할 촉매로서 중형기공성 니켈-알루미나 제로젤 촉매를 단일 공정 에폭사이드-유도 졸-겔법으로 제조하여 NA로 명명하였다. NA 촉매에 초기습윤함침법을 통해 조촉매로 알칼리 토금속(Mg, Ca, Sr 및 Ba)을 담지하여 M/NA (M = Mg, Ca, Sr 및 Ba)로 명명하였다. 상기 촉매를 천연가스의 수증기 개질 반응을 통한 수소 생산에 적용시켜 알칼리 토금속 조촉매가 촉매의 반응 활성에 미치는 영향을 조사하였다. 제조된 촉매의 표면적 및 기공 부피를 측정하기 위해 질소 흡탈착 분석을 수행하였고, 조촉매가 담지되었을 경우 기공이 막히면서 표면적 및 기공 부피가 감소하는 것을 확인하였다. 촉매의 결정상은 XRD 분석을 통해 확인하였고, NA와 M/NA 촉매 모두 니켈 알루미네이트에 해당하는 회절 패턴을 나타내었다. 촉매의 활성 금속-담체 간 상호작용을 확인하기 위해 TPR 분석을 수행하였고, 조촉매의 담지 여부에 상관없이 모든 촉매에서 표면 니켈 알루미네이트 상이 나타났다. 수소화학흡착 분석을 통해 환원된 촉매의 니켈 표면적을 측정하였으며, Mg/NA > Sr/NA > Ca/NA > NA > Ba/NA 순서로 니켈 표면적이 감소하는 것을 확인하였다. 촉매 활성은 LNG 전환율과 수소 수율로 평가하였고, 촉매의 니켈 표면적이 증가할수록 LNG 전환율 및 수소 수율이 증가하는 경향을 보였으며 제조된 촉매 중 Mg/NA 촉매의 활성이 가장 높게 나타났다. 사용된 촉매의 탄소 침적량은 CHNS 분석을 통해 측정되었으며, 알칼리 토금속이 첨가되지 않은 촉매에 비해 알칼리 토금속이 첨가된 촉매의 탄소 침적량이 더 적게 나타났다. 따라서 상기 실험 결과로부터, 알칼리 토금속이 중형기공성 니켈-알루미나 제로젤 촉매에 조촉매로 이용되었을 경우 천연가스의 수증기 개질반응에서 반응 활성 및 촉매 비활성화에 미치는 영향을 확인할 수 있었다. 상기 촉매 중 활성이 가장 좋았던 Mg/NA 촉매를 개선하기 위해 단일공정 에폭사이드 유도 졸-겔법과 초임계 이산화탄소 건조법을 및 초기습윤함침법을 이용하여 마그네슘이 담지된 니켈-알루미나 에어로젤 촉매(Mg/NAA)를 제조하였다. Mg/NAA 촉매와의 비교를 위해 니켈-알루미나 제로젤을 담체로 이용한 Mg/NAX 촉매를 상기 Mg/NA 촉매와 유사하게 제조하였다. 상기 촉매를 천연가스의 수증기 개질 반응을 통한 수소 생산에 적용시켜 촉매의 기공 특성이 촉매의 반응 활성에 미치는 영향을 조사하였다. 제조된 촉매의 표면적 및 기공 부피를 측정하기 위해 질소 흡탈착 분석을 수행하였고, Mg/NAA 촉매가 Mg/NAX 촉매에 비해 표면적, 기공 부피 및 평균 기공 직경이 더 크게 나타남을 확인하였다. 촉매의 결정상은 XRD 분석을 통해 확인하였고, NA와 M/NA 촉매 모두 니켈 알루미네이트에 해당하는 회절 패턴을 나타내었다. 촉매의 활성 금속-담체 간 상호작용을 확인하기 위해 TPR 분석을 수행하였고, Mg/NAA 촉매가 Mg/NAX 촉매에 비해 더 강한 금속-지지체 상호작용을 나타내는 것을 확인했다. 수소화학흡착 분석을 통해 환원된 촉매의 니켈 표면적을 측정하였으며, Mg/NAA 촉매가 Mg/NAX 촉매에 비해 니켈 분산도가 더 크게 나타난 것을 확인할 수 있었다. CH4-TPD 분석 결과 Mg/NAA 촉매가 Mg/NAX 촉매에 비해 메탄과의 친화도가 더 높은 것을 확인할 수 있었다. 천연가스의 수증기 개질 반응을 수행한 결과 니켈 분산도가 높고 메탄과의 친화력이 강한 Mg/NAA 촉매의 LNG 전환율과 수소 수율이 Mg/NAX 촉매보다 향상된 것을 확인하였다. 본 연구 결과를 통하여, 고활성 장수명의 천연가스의 수증기 개질 반응용 촉매를 개발하고, 촉매의 반응 활성과 니켈 분산도와의 상관 관계를 규명할 수 있었다.1. 서 론 1 2. 이론 및 배경 4 3. 실 험 8 3.1. 촉매 제조 8 3.1.1. 시약 8 3.1.2. 중형기공성 니켈-알루미나 제로젤 촉매(NA)의 제조 8 3.1.3. 알칼리 토금속이 조촉매로 이용된 중형기공성 니켈-알루미나 제로젤 촉매(M/NA, M = Mg, Ca, Sr 및 Ba) 제조 9 3.1.4. 마그네슘이 조촉매로 이용된 니켈-알루미나 에어로젤 촉매(Mg/NAA)의 제조 10 3.2. 촉매 특성 분석 12 3.2.1. N2 adsorption-desorption mesurement 12 3.2.2. ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) 12 3.2.3. XRD (X-Ray Diffraction) 12 3.2.4. H2-TPR (Temperature Programmed Reduction) 12 3.2.5. Hydrogen-chemisorption measurement 13 3.2.6. TEM (Transmission Electron Microscopy) 13 3.2.7. CHNS (Carbon, hydrogen, nitrogen and sulfur) elemental analyses 13 3.2.8. CH4-TPD (Temperature Programmed Reduction) 14 3.3. 천연가스의 수증기 개질 반응을 통한 수소 생산 15 3.3.1. 천연가스의 수증기 개질 반응 시스템 15 3.3.2. 촉매를 통한 천연가스의 수증기 개질 반응의 구성 15 4. 실험 결과 및 고찰 20 4.1. M/NA (M = Mg, Ca, Sr 및 Ba) 촉매를 이용한 천연가스의 수증기 개질 반응 20 4.1.1. 촉매의 물리화학적 특성 확인 20 4.1.2. 소성된 촉매의 결정 구조 확인 21 4.1.3. 소성된 촉매의 금속-지지체 상호작용 확인 22 4.1.4. 환원된 촉매의 특성 분석 23 4.1.5. 천연가스의 수증기 개질 반응 활성 25 4.2. Mg/NAA 촉매를 이용한 천연가스의 수증기 개질 반응 39 4.2.1. 촉매의 물리화학적 특성 확인 39 4.2.2. 소성된 촉매의 결정 구조 확인 40 4.2.3. 소성된 촉매의 금속-지지체 상호작용 확인 40 4.2.4. 환원된 촉매의 특성 분석 41 4.2.5. 천연가스의 수증기 개질 반응 활성 43 5. 결 론 55 참고문헌 57 Abstract 63Maste

Gravity separation of Cu-speiss and slag using Knelson concentrator and vibrating ball bed method

Even though the hydrometallurgical residue of non-ferrous metals contains small amounts of gold and silver, the residue has been landfilled due to low economic feasibility. Nowadays pyrometallurgical processes were developed to recover valuable metals from the residue, and, in these processes, gold and silver could be concentrated to an amount comparable to the content of gold or silver concentrates. In the pyrometallurgical process, impurities such as Fe, SiO2, and Ca are separated into slag, while Cu, Pb, Au, Ag are reduced to a metal phase and then recovered by specific gravity separation in the molten state at a high temperature. When separation efficiency is low, slag is mixed into the speiss, which causes many problems in the process. n this study, the slag mixed with the speiss obtained from the process was separated by conducting the specific gravity separation methods. In the case of the simulated sample experiment using the conventional Knelson concentrator, the separation efficiency decreased as the centrifugal force increased from 20% to 30%, and the possibility of specific gravity separation was confirmed. In the case of speiss mixed with slag, the separation efficiency was low at about 17%, indicating that it was difficult to separate specific gravity the materials. A newly designed Vibrating ball bed method using zirconia balls was investigated to separate the speiss and slag. As the number of particles increased, a particle interfere with the sinking of other particles. The separation efficiency increased to 100% at 22Hz (shaking power) with 3 limestones and 3 speiss, respectively.1. 서 론 1 1.1 연구 배경 1 1.1.1 아연제련잔사 처리 방법 2 1.1.2 아연제련잔사 중 유가금속의 가치 3 1.1.3 스파이스 중 유가금속의 정제 4 1.2 연구 내용 5 2. 이론적 고찰 6 2.1 습식비중선별 6 2.1.1 넬슨 선별기를 이용한 비중선별 7 2.2 건식비중선별 8 2.2.1 지르코니아볼을 이용한 비중선별 8 3. 넬슨 선별기를 이용한 선별 연구 10 3.1 시료의 물리적 특성 10 3.1.1 비중 10 3.1.2 입도 분포 11 3.2 시료의 화학적 특성 14 3.2.1 ICP 분석 14 3.2.2 SEM-EDS 분석 16 3.2.3 XRF 분석 18 3.3 실험 방법 및 조건 19 3.3.1 넬슨 선별기를 이용한 비중선별 19 3.4 넬슨 선별기 비중 분리 결과 21 3.4.1 모사 시료를 이용한 비중 분리 21 3.4.2 정상 스파이스와 슬래그가 혼입된 스파이스의 비중 분리 25 4. 진동볼층법을 이용한 선별 연구 27 4.1 지르코니아볼을 이용한 분리 27 4.2 진동볼층법 이용한 비중 분리 결과 28 4.2.1 진동 세기에 따른 순환 주기 28 4.2.2 입자 개수 및 진동세기에 따른 분리 효율 29 5. 결론 38 참고문헌 40Maste

Intestinal Behçet's disease: breath-hold MR imaging

BACKGROUND: To determine the feasibility of magnetic resonance (MR) imaging in the evaluation of intestinal Behçet's disease. METHODS: Eight patients diagnosed to have intestinal Behçet's disease prospectively underwent MR imaging. Five patients had previously undergone abdominal surgery for intestinal Behçet's disease 27-81 months previously. Breath-hold T2-weighted single-shot fast spin echo, T1-weighted multiplanar spoiled gradient recalled echo, and postgadolinium-enhanced fat-suppressed T1-weighted opposed-phase multiplanar spoiled gradient recalled echo images were obtained. MR findings were analyzed by three independent radiologists in terms of the presence and location of bowel wall thickening and ulcer, maximal bowel wall thickness, grade of bowel wall enhancement, and presence and nature of extraluminal manifestations. K statistics were used to evaluate interobserver variability. RESULTS: Seven cases (88%), including the five cases with previous operations, demonstrated bowel thickening of more than 9 mm and increased enhancement. Ulcer was depicted in four cases (50%) in the terminal ileum or an anastomosis site. Three cases (38%) showed extraluminal manifestation, such as mesenteric infiltration around the involved bowel (two cases) and a sinus tract to subhepatic abscess from perforation (one case). CONCLUSION: Breath-hold MR imaging is useful for the evaluation of bowel wall thickening, enhancement, mesentery infiltration, and abscess formation. Characteristic ulcerative lesions may be also depicted on T1- and T2-weighted breath-hold images. MR imaging is a useful method for postoperative follow-up study for the evaluation of recurrence.ope

Clinical evaluation of JPEG2000 compression for digital mammography

Medical images, such as computed radiography (CR), and digital mammographic images will require large storage facilities and long transmission times for picture archiving and communications system (PACS) implementation. American College of Radiology and National Equipment Manufacturers Association (ACR/NEMA) group is planning to adopt a JPEG2000 compression algorithm in digital imaging and communications in medicine (DICOM) standard to better utilize medical images. The purpose of the study was to evaluate the compression ratios of JPEG2000 for digital mammographic images using peak signal-to-noise ratio (PSNR), receiver operating characteristic (ROC) analysis, and the t-test. The traditional statistical quality measures such as PSNR, which is a commonly used measure for the evaluation of reconstructed images, measures how the reconstructed image differs from the original by making pixel-by-pixel comparisons. The ability to accurately discriminate diseased cases from normal cases is evaluated using ROC curve analysis. ROC curves can be used to compare the diagnostic performance of two or more reconstructed images. The t test can be also used to evaluate the subjective image quality of reconstructed images. The results of the t test suggested that the possible compression ratios using JPEG2000 for digital mammographic images may be as much as 15:1 without visual loss or with preserving significant medical information at a confidence level of 99%, although both PSNR and ROC analyses suggest as much as 80:1 compression ratio can be achieved without affecting clinical diagnostic performance.restrictio

Metastasis of primitive neuroectodermal tumor to the breast

We performed mammography and sonography on a 49-year-old woman who had a mass in her left axilla that had been present for 1 month and who had undergone excision of a primitive neuroectodermal tumor (PNET) on her back 1 year before. Mammography revealed 2 adjacent, dense nodules in the left breast and enlarged lymph nodes, without a fatty hilum or internal microcalcifications, in the left axilla. Sonography showed 2 round to oval, markedly hypoechoic nodules in the left breast and enlarged, markedly hypoechoic lymph nodes, without microcalcifications, in the left axilla. We then performed sonographically guided core biopsy. Histopathologic analysis of the specimens confirmed the presence of PNET in the left breast and axillary lymph nodes. The patient was then treated with chemotherapy. To our knowledge, this report is the first to describe radiologic findings of metastasis of PNET to the breast. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30:374–377, 2002; Published online in Wiley InterScience (www.interscience.wiley.com).ope