A Study on the Optimization of Miller Cycle for Naval Vessel Diesel Engine

Since May 2005, all ocean-going vessels built after January 2000 have had to comply with the emission control regulations according to Annex Ⅵ of the MARPOL 73/78 convention. Thesse regulations set limits on exhaust gas emissions for nitrogen oxides(NOx), sulphur oxides(SOx) and particulate matter(PM) from ships. The air pollutants as NOx, SOx, PM etc are harmful things for human health. They can be obsorbed onto the lung and cause lung disease like a lung cancer. And they are blamed as one of the major causes of photochemical smog and acid rains. The NOx emission is related with engine combustion process as like high peak pressure, high compression ratio, high rate of fuel delivery. In other words, the higher combustion temperature, the grater amount of NOx formation. Much of NOx emission can be decreased by the technology today. For example the fuel injection control by CR(Common Rail) and electronic control, EGR(Exhaust Gas Recirculation), SCR(Selective Catalytic Reduction) which using ammonia or urea, Miller Cycle and 2-stage turbocharging, etc. Miller Cycle is one of the few measures that can be applied in an internal combustion engine to simultaneously reduce NOx emission and fuel consumption. Since all engine builders strive to meet engine emission limits without any loss of efficiency, practically every modern engine is operated today with at least moderate Miller timing. In this study, a performance simulation about naval vessel diesel engine carried out through a mathematical modeling techniques for flow analysis of the working gas. And the simulation results were compared with measured data to evaluate reliability of simulation. Finally we obtained reliable simulation results. The purpose of this study is to predict effect of miller cycle for naval vessel diesel engine. By changing the intake valve closing timing and boost pressure, the engine performance is simulated. And we found the best valve timing and proper boost pressure.List of Tables ⅲ List of Figures ⅴ Abstract ⅵ Nomenclature ⅷ 제1장 서 론 1 1.1 연구 배경 1 1.2 연구 내용 3 제2장 친환경 엔진의 요구와 대책 4 2.1 유해 배기가스 배출규제 규정 4 2.2 유해 배기가스 감축 대책 9 2.2.1 배기가스 재순환(EGR) 장치 10 2.2.2 선택적 촉매 환원(SCR) 장치 11 2.2.3 EGR 및 SCR 장치 함정 설치 가능성 고찰 12 제3장 밀러 사이클(Miller Cycle) 효과 15 3.1 밀러 사이클의 원리 15 3.2 밀러 사이클의 열효율 17 3.3 엔진의 밀러 사이클화 연구 및 적용사례 21 제4장 디젤기관의 성능 시뮬레이션 프로그램 23 4.1 이론 해석에 이용된 주된 가정 23 4.2 실린더 및 용기내의 상태 변화 25 4.2.1 가스 교환 과정 25 4.2.2 압축 팽창 과정 27 4.3 NO 생성량 계산방법 29 4.4 과급기 효율 계산방법 30 4.4.1 입력데이터 및 가정 30 4.4.2 과급기 효율 계산과정 31 4.5 시뮬레이션 대상엔진 및 계산 모델 32 4.5.1 시뮬레이션 대상엔진 32 4.5.2 계산모델 및 조건 32 4.6 시뮬레이션 결과 고찰 34 제5장 밀러 사이클 적용시 성능예측 36 5.1 밀러 사이클 적용 36 5.1.1 EIVC 적용 36 5.1.2 LIVC 적용 39 5.2 밀러 사이클 적용 결과 고찰 39 5.2.1 25% 부하조건 40 5.2.2 50% 부하조건 44 5.2.3 75% 부하조건 48 5.2.4 100% 부하조건 52 제6장 결론 56 참고문헌 57Maste

Epidemiology of HIV/AIDS in East Asia

Background:Recent predictions of catastrophic epidemic surge of HIV infection in East Asia concern experts and governmental organizations. As in many other areas, countries in East Asia show diversities in their HIV epidemics, both geographically and temporally. However, they have similar regional, cultural and racial characteristics which allow them to have certain common factors. Having a clear picture of the current extent and feature of HIV/AIDS in this region is a very difficult task largely due to the fast pacing of expending epidemic and difficulty in data-sharing among countries in the region. Hence, we decided to study the epidemiologic feature of HIV/AIDS in East Asia through East Asia Network on HIV (EAN-HIV). Materials and Methods:The epidemiological patterns of HIV/AIDS in East Asian countries were investigated by collecting data through EAN-HIV. Results:The HIV/AIDS epidemic in East Asia started relatively late at mid 1980s. Since then, the number of newly infected HIV/AIDS cases has been steadily increasing with stiffer escalation in recent years. In China and Taiwan, IDU plays an important part in the swiftly growing HIV epidemics; however, in other regions like Korea, Japan, and Hong Kong, MSM (men who have sex with men) seems to be more of a problem. The major subtypes of HIV in East Asia are subtype B, C, and CRF01_AE, and rapidly evolving circulating recombinant forms (CRF) between subtypes such as CRF07_BC give dynamic change to the current status. Conclusion:The incidence of HIV/AIDS is rapidly increasing in East Asia. The epidemic pattern has undergone dynamic changes over time. China seems to be the leading source of HIV/AIDS epidemic in East Asia due to its large population and rapidly growing epidemics.ope

A Case of Brucellar Spondylitis with Multiple Spine Involvement

Brucellosis, a zoonosis with world wide distribution, is a systemic infection that affects several organs and has protean presentation. Although spondylitis is universally the most common complication of brucellosis and difficult to treat, there is no consensus on the preferred combination of antibiotics use. The authors report a case of a 58-year-old male patient with brucellar spondylitis involving several vertebrae. Diagnosis was made by positive blood culture and magnetic resonance imaging. The authors use a combination method of doxycycline, ciprofloxacin and streptomycin for a period of 3 months. The systemic symptoms were improved after treatment.ope

Prognosis Factors of Clostridium difficile Associated Diarrhea

Background:Clostridium difficile associated diarrhea (CDAD) has a wide range of clinical manifestations. The prognostic factors of CDAD are not fully understood. Materialsand Methods:A retrospective cohort study of 115 patients with CDAD from Aug. 2002 to Dec. 2003 was conducted to evaluate prognostic factors of CDAD. Bacteriologic factors were determined by detecting the binary toxin gene, tcd A, tcd A rep and tcd B gene. Poor prognosis was defined as diarrhea more than 10 days even with classic treatment, recurrence, death, and moribund discharge. Results:Approximately 79% of isolated strains were toxin A+/B+ strains and 21% were toxin A-/B+ strains. There was no difference in prognosis between toxin A+ and toxin A- strains. 39 (33.9%) cases showed poor prognosis and 76 (66.1%) cases showed good prognosis. Univariate analyses revealed that the poor prognostic factors were old age over 70 years old, male, the number of antibiotics used after onset of symptom, the administration of carbapenems, aminoglycosides, glycopeptides after onset of symptom, history of DM and stroke, and high Charlson comorbidity index. Multiple logistic regression analysis identified old age over 70 years old (odds ratio=3.378, P=0.009) and the administration of carbapenems after onset of symptom (odds ratio 7.210, P<0.001) as the independent poor prognostic factors. Conclusion:Old age over 70 and the administration of carbapenems after onset of symptom were the poor prognostic factors for CDAD caused by none-binary toxin producing strains.ope

흑색마우스에서 자외선을 조사한 표피색소세포에 탈색소제제가 미치는 영향

의학과/박사[영문] [한글] 인체의 정상 피부색은 주로 표피에 침착된 멜라닌색소와 카로티노이드색소 그리고 진피 혈관내의 혈색소등에 의해 영향을 받으나 이중 피부색에 가장 중요한 영향을 미치는 것 은 멜라닌색소이다. 피부의 멜라닌색소 침착을 두가지 범주로 구분할 때 첫째는, 자외선 이나 또는 환경요인의 영향없이 유전적으로 결정된 색소세포의 기능에 의해서만 멜라닌색 소 침착이 형성되는 고유의 피부색 (constitutive skin color)과 둘째는, 고유 피부색에 더하여 자외선이나 그외 다른 환경요인에 의해 유발되는 임의의 피부색 (facultative ski n color)으로 구별될 수 있다. 자외선 조사후 유발되는 멜라닌색소의 증가는 tyrosinase활성화 및 활동성 색소세포 수 의 증가와 연관이 있는 것으로 밟혀졌으며, Rosdahl(1979)은 자외선이 조사되지 않은 실 험동물에 자외선을 일정양 반복조사할 경우 DOPA양성 색소세포의 수적 증가는 자외선조사 중단후 장기간 활성화되어 지속되는 현상을 보고하였다. 본 실험에서 저자는 실험동물에 자외선을 반복조사하여 색소세포 수의 증가와 멜라닌 생성을 유발시킨 후 성분이 다른 탈색소제제들을 도포하여 상기 제제들이 표지의 색소세 포에 미치는 영향을 관찰하였다. 실험동물로 성숙된 C57Bl 웅성마우스 72마리를 사용하였으며 전체 마우스의 양쪽 귀에 UV-B를 10일간 조사하였다. UV-B의 광원으로 YS UVB-400을 사용하였으며 파장은 290∼325 nm(주파장, 301nm) 일일 조사량은 100mJ/㎠였다. 자외선 조사완료후 72마리의 마우스를 무작위로 3군으로 나누어 다음과 같이 실험하였 다. 제 Ⅰ군: 연고기제 도포군(대조군)………………………………………………… 24마리 제 Ⅱ군: 20% monobenzylether of hydroquinone (MBEHQ) 도포군………………24마리 제 Ⅲ군: 20% azelaic acid(AZA) 도포군……………………………………………24마리 상기 탈색소제제를 마우스의 양쪽 귀에 매일 오전 오후 2회씩 6주간 도포하였으며, DOP A염색과 광학현미경 및 전자현미경 관찰을 위해 실험 6주동안 매주 각군당 4마리의 마우 스 양즉 귀 배부에서 생검하였다. 실험결과를 요약하면 다음과 같다. 1. 20% MBEHQ와 20% AZA도포군은 대조군에 비해 DOPA양성 색소세포의 수와 크기, 둘레 길이 및 멜라닌색소 형성에 유의한 감소를 보여 탈색소제제로서 의의있는 효과를 나타내 었다. 2. 두 실험군간의 비교에서 AZA도포군의 DOPA양성 색소세포수는 도포 6주 후에 MBEHQ 도포군보다 의의있게 감소되었으며, hematoxylin-eosin 염색상 MBEHQ도포군은 AZA도포군 에 비해 도포 4주 이후부터 표피의 현저한 비후를 나타내었다. 3. 실험약물이 DOPA양성 색소세포의 형태에 미치는 영향 중 특이한 현상은 MBEHQ도포군 에서 도포 3주 후에 수상돌기만 감소되거나 소실된 구형의 비정형 색소세포가 발견된 것 이며, AZA도포군에서는 색소세포의 세포체와 수상돌기가 모두 도포기간에 비례하여 감소 되는 소견을 보였다. 4. 전자현미경 소견상, 대조군에서 실험 전기간에 걸쳐 각질형성세포 내와 색소세포 내 에 stage Ⅳ의 멜라닌소체들이 다수 관찰되었으며 실험군에서는 도포 3주 후부터 각질형 성세포 내에서 공포(vacuole)에 들어있는 전자밀도가 낮은 소량의 멜라닌소체들이 관찰되 었다. 이러한 현상은 MBEHQ도포군에서 더 현저하였다. 도포 5주와 6주 후에는 실험군의 각질형성세포 및 색소세포 내에서 멜라닌소체가 소실되었거나 드물게 관찰되었다. 이상의 결과를 종합하면, MBEHQ와 AZA가 탈색소제제로서 작용하는 기전은 상기 약제 모 두 표피색소세포에 작용하여 탈색소 효과를 나타내는 것으로 사료되며 MBEHQ는 장기간 도 포시 마우스 피부에 자극현상을 유발하는 것으로 관찰되었다. The Effect of Depigmenting Agents on Epidermal Melanocytes in UV-irradiated Mice Young Keun Kim Department of Medical Science The Graduate School, Yonsei University (Directed by Professor Yoon-Kee Park, M.D.) Normal human skin colors are produced by four skin pigments: in the epidermis, carotenoids and melanin; and in the dermis, oxygenated and reduced hemoglobin. Of these pigments, the major color determinant is melanin. Melanin pigmentation of the skin can be divided into two categories. The first, constitutive skin color designates the amount of cutaneous melanin pigmentation generated in accordance with cellular genetic programs in the absence of direct influences by radiations. The second, facultative (inducible) skin color characterizes the increase in melanin pigmentation above the constitutive level and arises from the complex interplay of solar radiation and other environmental factors upon the genetically endowed melanogenesis of the individual. Published reports regarding the increased melanin pigmentation following ultraviolet radiation suggest that an increase in tyrosinase activitr and a numerical increase of functioning melanocytes are responsib1e for enhanced pigment production. In this experiment, we induced activation of melanocytes and melanin pigmentation in the epidermis of C 57 B1 mice by UV-B irradiation. Aftar UV-B irradiation we observed the effect of the two different kinds of depigmenting agents on the epidermal melanocytes in UV-irradiated mice. A total of 72 mice had both their ears irradiated by UV-B daily for 10 days. The light source was YS UVB-400 with a wave length spectrum of 290∼325nm(peak out-put at 301). The lamp to target distance was 30㎝ and daily dose was 100 mJ/㎠. After irradiation, 72 mice were divided into 3 groups in random sampling and the application of depigmenting agents on each group is as follows. Group Ⅰ: cream base(control)……………………………………………………………24 Group Ⅱ: 20% monobenzylether of hydroquinone (MBEHQ)……………………………24 Group Ⅲ: 20% azelaic acid(AZA)…………………………………………………………24 The application of the depigmenting agents was done twice a day on both ears of mice for 6 weeks and four mice in each group were sacrificed by the end of the 1st, 2nd, 3rd, 4th, 5th, and 6th week of the application. Both ears of the mouse were cut at the base for split-dopa preparation and for light microscopic and electron microscopic preparation. The results are summarized as follows: 1. Both of MBEHQ and AZA showed significant diminution in the size, circumference, and number of dopa-positive melanocytes in C 57 Bl mouse skin. 2. As compared with the two experimental groups, the number of dopa-positive melanocytes tended to be of smaller quantity in AZA treated group by the end of the 6th week of the application. In areas treated with MBEHQ, the vertical sections stained with hematoxylin-eosin showed marked epidermal thickening after the 4 weeks' application. 3. In areas treated with MBEHQ, many of the remaining melanocytes were abnormal in shape having lost their dendrites so that they appeared as round bodies after the 3 weeks' application. In areas treated with AZA, there were no abnormal morphologic changes such as round bodies throughout the period of experiment. 4. On electron microscopic findings, there were many melanosomes of stage Ⅳ in the keartinocytes and melanocytes during the experimental period in the control group. In the experimental groups, a small amount of melanosomes surrounded by vacuoles in the cytoplasm of keratinocytes was a prominent feature after the 3 weeks' application especially in MBEHQ treated group. By the end of the 5th and 6th week of the application in the experimental groups, there was a small amount or no melanosomes in the epidermis. In summary, the present study suggests that both of MBEHQ and AZA inhibit melanin pigmentation by the action on epidermal melanocytes either by destroying or inactivating melanocytes and the skin treated with MBEHQ skewed marked epidermal thickening comparing to the skin treated with AZA.restrictio

이종 기상 증기 증착 중합을 이용한 고분자카본 나노튜브 제조

Thesis(master`s)--서울대학교 대학원 :응용화학부,2005.Maste

라디칼반응을 이용한 산소고리화합물의 합성

Thesis (master`s)--서울대학교 대학원 :화학과 유기화학전공,1996.Maste

Chloroquine resistance and analysis of single-nucleotide polymorphisms of pvmdr1 gene in Korean vivax malaria

의학과/박사[한글] 배경: 1997년 이후 비무장지대 근처 말라리아 위험지역을 중심으로 시작한 한국군의 말라리아에 대한 hydroxychloroquine/primaquine 예방요법은 말라리아 발생율 감소에 기여하고 있으나, chloroquine 내성 말라리아 출현의 위험성이 있다. 이에 연구자는 예방약을 적절히 복용하였음에도 불구하고 발생한 말라리아의 빈도 및 chloroquine 내성감시를 시행하였고, pvmdr1 유전자 단염기변이와 chloroquine 내성과의 연관성을 조사하였다.방법: 말라리아 발생 위험지역의 한국군을 대상으로 예방을 위하여 2006년 5월부터 hydroxychloroquine sulfate 400 mg이 말라리아 유행기에 1주마다 투여되었다. 2006년 6월부터 9월까지 비무장지대 근처의 경기도에 주둔한 한국군에서 발생한 102명의 환자를 대상으로 말라리아 발생 이전의 예방요법의 적절성을 조사하였다. 이 중 85명의 환자를 대상으로 28일간 chloroquine 치료 내성 감시를 시행하였으며 이들 환자로부터 분리된 Plasmodium vivax로부터 pvmdr1 유전자의 단염기변이를 분석하였다.결과: 102명의 환자 중 예방요법이 적절하였던 환자는 66명(64.7%) 이었고, 불규칙한 복용 11명(10.8%), 예방약을 전혀 복용하지 않았던 환자는 25명(24.5%)이었다. Chloroquine 치료 내성 감시를 시행한 모든 환자에서 chloroquine 표준치료 3일 이후의 말초혈액도말검사에서 말라리아 원충은 관찰되지 않았다. pvmdr1 유전자 분석을 시행한 78예 모두에서 F1076L 변이가 관찰되었다.결론: 연구 대상 말라리아 발생 환자 중 2/3가 적절히 예방약을 복용하고 있었다. Chloroquine의 치료실패는 없었으나, pvmdr1 유전자의 F1076L 변이가 chloroquine 예방실패와 관련 있을 것으로 생각된다. [영문] Background: Chemoprophylaxis with chloroquine (CQ) and primaquine has been used in the Republic of Korea (ROK) Army since 1997 to reduce the number of the malaria cases. It has contributed, in part, to the decrease in the number of malaria cases among military personnel. However, chemoprophylaxis may facilitate the development of CQ-resistant strains of Plasmodium vivax. We investigated the breakthrough malaria infection and the therapeutic efficacy of CQ in P. vivax in ROK. And the pvmdr1 gene polymorphisms and its relevance to CQ-resistance in P. vivax were evaluated.Methods: Chemoprophylaxis with hydroxychloroquine sulfate (400 mg, once per week) was started in May and continued throughout the transmission season. From June to September 2006, 102 soldiers with vivax malaria near the demilitarized zone in Gyeonggi-do, ROK, were enrolled. Breakthrough malaria was defined when a patient had taken all prophylactic doses every week prior to infection. The status of chemoprophylaxis was determined by the interview. In 85 patients, therapeutic efficacy was monitored during 28 days after standard CQ treatment. The single nucleotide polymorphisms of pvmdr1 in the isolates from these patients were analyzed.Results: Among 102 malaria cases occurring during study period, breakthrough malaria was observed in 66 patients (64.7%) who had complete compliance. Incomplete compliance was 11 cases (10.8%) and no compliance was 25 cases (24.5%). In all patients enrolled in therapeutic efficacy monitoring, parasitemia had not been observed since 3 days after standard CQ treatment. Nucleotide polymorphism at 1 codon (F1076L) was found in all analyzed isolates.Conclusion: Breakthrough malaria was observed in about two thirds of malaria cases occurring in the area on chemoprophylaxis. Although there was no treatment failure, it was likely that the F1076L mutation of the pvmdr1 gene might contribute to CQ-prophylaxis failure in P. vivax.ope

Effect of tuberculosis on the course of HIV infection

의학과/석사[한글] 사람면역결핍바이러스(human immunodeficiency virus; HIV) 감염자에서 발생하는 기회감염 중 결핵은 국내뿐만 아니라 세계적으로 가장 흔한 후천성 면역결핍증(acquired immunodeficiency syndrome; AIDS) 정의 질환이면서 HIV 감염자의 주요 사망 원인이다. 결핵이 HIV의 복제를 증가시킨다고 알려져 있지만 임상적으로 HIV 감염의 질병경과를 악화시킬 수 있는지에 대하여는 논란이 많아 국내에서의 결핵이 HIV 감염의 질병경과에 미치는 영향을 조사하였다.연세대학교 의과대학 세브란스병원에서 1992년부터 2004년까지 HIV 감염자중 결핵으로 진단 받은 44예의 환자군과 환자군과 비슷한 CD4+ T세포수 (±25/㎕)에 대응하는 결핵 발병이 없었던 HIV 감염자 44예의 대조군을 후향적 코호트 연구방법으로 viral load, 관찰 시작 후 AIDS 정의 질환의 발생 빈도, 생존율을 비교하여 결핵이 HIV 감염의 질병경과에 미치는 영향을 조사하였다.환자군과 대조군 간의 연령, 성별, 강력한 항레트로바이러스 치료(highly active anti-retroviral therapy; HAART) 유무의 차이는 없었다. 평균 CD4+ T세포수도 환자군 84.5개/㎕, 대조군 84.0개/㎕로 차이가 없었다. 평균 viral load는 환자군 6.2×105 copies/㎕, 대조군 2.9×105 copies/㎕로 환자군에서 높게 나타났으며(p=0.001), 관찰 시작 후 AIDS 정의 질환의 발생 빈도도 환자군 2.9/100 person-months, 대조군 1.2/100 person-months로 대조군에 비하여 환자군이 2.43(95% CI: 1.02-5.14)배 높았다. 환자군의 사망률 또한 대조군보다 높았으며(p=0.025, log rank), 결핵이 HIV 감염자의 사망에 미치는 기여 위험도는 2.09(95% CI: 1.07-4.08)였다.상기의 결과를 통하여 HIV 감염자에게 결핵이 발생하면 viral load가 증가하여 면역 저하를 증가시킴으로 기회 감염의 빈도를 높이고 결국 사망에 영향을 줄 수 있어 결핵이 HIV 감염자의 질병 경과를 악화시킨다는 것을 알 수 있었다. [영문]Background: In Korea, endemic area of Mycobacterium tuberculosis (TB) infection, the incidence of new HIV infection has been persistently increasing each year and HIV/TB coinfected patients are common. Several studies suggested that TB enhanced the replication of HIV and could accelerate the course of HIV infection. So, we investigated the effect of tuberculosis on the course of HIV infection in Korea.Methods: In an observational study of retrospective cohorts at Severance Hospital, Yonsei University College of Medicine, Seoul, Korea from 1992 to 2004, the evolution of 44 HIV-infected patients with TB (cases) was compared with that of the absolute CD4+ T cell count matched(±25 cells/㎕) 44 HIV-infected patients without TB (control subjects). To determine the effect of tuberculosis on the course of HIV infection, the incidence rate of opportunistic diseases and the mortality were evaluated.Results: There were no significant differences between the cohorts for age, sex and antiretroviral therapy including highly active antiretroviral therapy. The mean CD4+ T cell counts were similar between cases and control subjects (84.5 cells/㎕ versus 84.0 cells/㎕, respectively). The mean viral load was much higher in cases than that of control subjects (6.2×105 copies/㎕ versus 2.9×105 copies/㎕, respectively, p=0.001). The incidence rate of new subsequent AIDS-defining opportunistic diseases in cases was 2.9 infections per 100 person-months compared with 1.2 infections per 100 person-months in control subjects for an incidence rate density ratio of 2.43 (95% CI: 1.02-5.14). Cases also had a shorter overall survival than did control subjects (p = 0.025, log rank test). Tuberculosis in HIV-infected patients was associated with an increased risk for death (hazard ratio = 2.09, 95% CI: 1.07-4.08).Conclusion: Tuberculosis in HIV-infected patients was related to more frequent AIDS-defining opportunistic diseases and shorter survival.ope