The Relation between Human Behavior and Safety in the Collision Avoidance Situation

해상 사고의 대부분이 인적 과실에서 비롯하고 있으며 특히, 항해 중 다른 선박과의 충돌 관계에 있어 사고 가능성은 항해 환경과 운항자의 선박 조종 능력에 따라 변화한다고 볼수 있다. 그러므로 선박간의 충돌 관계에 있어 인간이라는 요소는, 매우 중요한 역할을 하고 있고 이러한 운항자에 의한 수많은 사고 발생의 원인을 줄이고 안전을 도모하기 위해서 선행되어야 할 연구 대상이 된다. 그러나 인간이라는 존재는 상황에 따라 다양하게 변화하고 그 변화 역시 예측하기 힘든 불확실한 성질을 가지므로, 인간의 어떠한 요소들이 사고를 발생시키고 또한 그 가능성을 높게 하는지 구체적으로 밝히는 데에는 여러 가지 어려움이 있었다. 이와 같은 연구의 어려움으로 인하여 지금까지는 해상 사고와 관련된 인적 요소에 대하여 통계자료의 분석과 정성적인 연구만 수행되어 왔으나, 이 논문에서는 지금까지의 통계 자료와 정성적인 연구에서 나아가 인간의 행동과 안전성 사이의 관계에 대하여 공학적인 관점에서 접근함으로써 운항자들의 일반적인 행동 양상이 선박의 안전 운항에 미치는 영향을 정량적으로 나타내고자 하였다. 즉, 이러한 인간의 행위를 정량적으로 나타냄으로써 운항자들의 일반적인 조종 특성에 따른 충돌 위험 가능성을 구체적으로 밝히고자 하였다. 이 연구에서는 인간의 행위를 중심으로 안전성과의 관계를 분석하고 검토하기 위해서, 선박 조종 시뮬레이터를 이용한 BTM (Bridge Team Management) 훈련을 실시하였으며 또한 선장, 1항사, 2항사, 3항사를 포함한 91명의 운항자들을 대상으로 설문조사를 행하였다. BTM 훈련에 있어서는 충돌 관계에서 상대 선박과의 위험한 상황을 인식하는 시간 및 피항을 취하는 시간 등과 같은 운항자들의 조종 특성을 조사하고, 이러한 요소들을 바탕으로 위험도의 측정 기준의 하나로 여겨지고 있는 최소 근접 거리(CPA)와의 상관관계를 구하였다. 그리고 운항자의 조종 능력과 충돌 가능성과의 관계를 그래프로 나타내고 인간의 행위에 따른 사고 발생 가능성의 예측 및 안전을 위한 운항 지침의 방향을 제시하였다. 또한 BTM 훈련과 더불어 운항자들을 대상으로 실시한 설문 조사를 바탕으로 항해 환경에 따른 조종 특성의 변화를 살펴보고 각각의 내용을 비교 분석하였다. 그리고 조종 특성의 변화의 주요 원인으로서 항행 수역의 선박 교통량에 의한 밀집도를 제시하고 그 관련성을 살펴보았다. 이와 같이 BTM 훈련과 설문조사의 내용을 분석한 결과로서, 항해 환경에 따른 운항자들의 조종 특성의 변화와 그 조종 특성의 변화에 따른 충돌 가능성의 변화를 나타내었다. 즉, 수역의 넓이, 복잡성, 상대 선박과의 피항 관계 등과 같은 항해 환경의 변화에 따라 운항자의 조종 특성이 변화하고 있으며 그 변화에 따라 안전성 또한 변하는 것이 밝혀졌다.Abstract i 1. Introduction 1 1.1 Purpose and background 1 1.2 Composition of the thesis 2 2. Relations between navigational environment and ship-handling 3 2.1 Introduction 3 2.1.1 Conditions of the questionnaire 3 2.2 Variation of ship-handling characteristics caused by navigational environment 8 2.2.1 Crossing situation when an own ship is a stand-on vessel 8 2.2.2 Crossing situation when an own ship is a give-way vessel 13 2.2.3 Head-on situation 18 2.2.4 Overtaking situation 22 2.3 Summary and discussion 27 3. Relations between ship-handling ability and risk of collision 29 3.1 Introduction 29 3.1.1 Definition of the correlation coefficient (r) 30 3.2 Variation of collision probability caused by ship-handling ability31 3.2.1 Operators’ behavior for a small high-speed vessel 32 3.2.2 Operators’ behavior for a container vessel 41 3.3 Summary and discussion 45 4. Variation of ship-handling characteristics 47 4.1 Introduction 47 4.2 Comparison between the questionnaire and the BTM training 47 4.2.1 Comparison between the questionnaire and the BTM training in case of small high-speed vessel 48 4.2.2 Comparison between the questionnaire and the BTM training in case of container vessel 52 4.3 Reasons for the variation of ship-handling haracteristics 55 4.3.1 Traffic volume 56 4.3.2 Other reasons 60 4.4 Summary and discussion 61 5. Conclusion 62 Reference 65 Appendix 6

Integrated analysis of genomic and transcriptomic data

In different tissue of multicellular organisms, the function and the phenotype of the tissues are formed by the tissue specific gene expression. Therefore, it is important to understand how genes are turned on and off in specific tissues and how the numbers of different gene expression products are determined. These aspects of transcription can be defined as expression breadth and expression level, respectively. Based-on the biological mechanisms of gene regulation, the information to regulate the gene expression can be categorized into two groups. One is the genomic information such as GC contents and the other is the epigenomic information such as DNA methylation. Because of the complexity of gene expression regulation in multi-cellular organism, the combined analysis of genomic and epigenetic information is an efficient way to understand the underlying mechanism of gene regulation. Due to the mutagenic nature of DNA methylation, CpG depletion is caused in highly methylated region. In this thesis, the CpG depletion measures (CpG O/E and Pearsons residual) were shown to be negatively correlated with DNA methylation fraction in model organisms. Accordingly, it is possible to detect the evidence of the DNA methylation by measuring the CpG depletion in genomic data and the CpG depletion measure can be included in the genomic traits. The correlations between each genomic trait and two aspects of gene expression show similar direction. From this result, it is possible to infer that both of the gene expression traits may share the molecular mechanisms. However, it is necessary to identify the relative significance of each genomic trait on these two expressional aspects to explain distinctive molecular mechanisms regulating gene expression levels and breadths. To this end, a novel method was suggested to compare the effect sizes of each genomic trait on the two expressional aspects of gene based-on multivariate multiple regression in this thesis. The mean size of exons (gene compactness), codon usage bias and non-synonymous substitution has a strong effect on expression level and the CpG O/E (normalized CpG depletion) in promoter and synonymous substitution has a strong effect on expression breadth. The CpG O/E in intron shows an opposite pattern to the CpG O/E in promoter in the human genome. This suggested that DNA methylation may play multiple roles depending upon its genomic targets. These findings provide clues toward distinctive molecular mechanisms governing different aspects of gene expression.유전자의 발현은 다세포의 복잡한 생물체에 있어서 조직의 다양성에 중요한 역할을 하고 있다. 특정 유전자가 발현되느냐 그렇지 않으냐에 따라 세포의 표현형과 기능이 달라지기 때문이다. 따라서 이러한 유전자 발현을 조절하는 분자적 메커니즘을 이해하는 것은 중요한 일이다. 지금까지의 연구에서 알려진 유전자 발현과 연관된 서열상 정보들은 서로 연관성을 가지고 있다. 따라서 이러한 유전자 발현의 분자적 메커니즘을 이해하기 위해서는 서열상의 특징들과 유전자 발현과 연관된 특징들을 통합하여 분석하는 것이 중요하다. 유전자 발현의 특징은 두 가지로 표현 될 수 있는데, 첫 번째는 발현되는 유전자의 양이 얼마 인가로 expression level로 표현될 수 있다. 그리고 또 다른 한 가지는 얼마나 많은 종류의 조직에서 발현이 되느냐로 expression breadth로 정의 된다. Expression level과 expression breadth 각 각과 DNA 서열상 특징의 상관관계는 서로 비슷한 방향성을 가지고 있다. 이 결과로부터 expression level과 expression breadth는 많은 부분의 분자적 메커니즘을 공유하고 있을 것이라고 예측할 수 있다. 하지만, 이 두 유전자 발현의 특징을 구분하는 분자적 메커니즘을 찾아내는 것 또한 중요한 문제이다. 따라서, 이 논문에서는 multivariate multiple regression 모델을 이용하여, 여러 DNA 서열 상의 특징들과 유전자 발현의 특징들 과의 상관관계를 밝혀 내고, 각 DNA 서열 상 특징들의 expression level, expression breadth에 대한 영향력을 비교하는 새로운 방법을 제안 하였다. 이 방법을 이용하여 exon의 평균 사이즈와 codon usage bias, non-synonymous substitution이 expression breadth에 비해 expression level에 더 많은 양향력을 가지고 있다는 것을 알아내었으며, promoter 영역의 CpG O/E와 synonymous substitution은 expression breadth에 더 많은 영향력을 가지고 있다는 것을 알아 내었다. 또한, 결과를 보면, intron 영역의 CpG O/E의 경우 promoter 영역의 CpG O/E와 서로 반대되는 상관관계를 보이고 있는데, 이것은 DNA methylation이 유전자의 어느 영역에 위치하느냐에 따라서 그 역할이 달라질 수 있다는 것을 의미 할 수 있다. 이 결과들은 유전자 발현의 level과 breadth를 조절하는 구별된 분자적 메커니즘이 있다는 것의 증거가 될 수 있다. 위의 분석에 앞서서 유전자 발현의 중요한 역할을 한다고 알려져 있는 DNA methylation에 대해서 연구를 수행하였다. DNA methylation이 많은 영역의 경우 CpG 서열의 감소가 발견되는데, 이것을 표현하는 알려진 방법이 CpG O/E를 계산하는 것이다. 이 논문에서는 서열상에서 CpG 감소 정도를 예측할 수 있는 새로운 방법을 제시하고, CpG의 감소 정도가 다른 유전자들을 분류하여 그 특징을 살펴보는 작업을 수행 하였다. 이 과정에서 methylation과 관련된 CpG 감소현상을 서열정보로부터 계산할 수 있는 프로그램을 계발하였다.Docto

Factors affecting tumor necrosis after transarterial chemoembolization for hepatocellular carcinoma.

의학과/석사[한글] 간세포암으로 수술 전 경동맥화학색전술(TACE)을 받은 환자에서 병리학적 괴사율을 알아 보고, 괴사율에 영향을 미치는 영상 소견, 색전 시술방법 및 병리학적 인자를 알아 보고자 하였다. 총 52명의 간암 환자(남:여 = 44:11, 평균 49세)의 55개 병변을 대상으로 경동맥색전술을 시행한 후 부분적 간절제술 후 병리학적 괴사율(%)을 조사하였다. 색전술 전 영상으로(CT/ MRI) 종양의 크기, 변연(분명/불분명), 피막 여부, 혈관 침범 여부를 평가하고, 색전술 시 간문맥/간정맥 침윤 여부, 종양의 공급혈관 종류(간동맥/간외동맥), 색전술을 시행한 선택 동맥 위치(엽성/분절성/아분절성), 항암제 및 리피오돌양, 젤폼 사용 여부, 종양 내 또는 종양 주변의 동문맥/동정맥 단락 여부를 조사하였다. 색전술 후 수술까지의 기간을 추적하고, 병리학적 괴사 정도, 성장 양상, 분화 정도, 피막 형성 여부 등을 조사하였다. 이들 방사선학적, 병리학적 인자들과 괴사율의 상관 관계를 통계적으로 검증하였다. 수술 후 영상 진단으로 재발 여부를 추적하고, 종양 괴사율과 재발 여부나 재발까지의 기간과 상관 관계를 살펴 보았다. 종양 크기는 1~12cm으로 평균 5.3cm이었다. 술 전 경동맥색전술을 1회 받은 종괴가 45개, 2회가 10개였으며, 색전술 후 수술까지의 기간은 6~485일(평균 75.5일)이었다. 종양 괴사율은 100%가 13예, 95~99%가 14예, 80~94%가 13예, 50~79%가 7예, 50% 미만이 8예였으 며, 평균 79.5%였다. 크기가 3cm 이상으로 클수록, 간외동맥 공급을 받는 경우, 피막이 없는 경우, 병리학적 성장 양상이 침윤형인 경우, 분화도 등급이 높은 경우 괴사율이 통계적으로 유의하게 낮았다(p<0.05). 괴사율과 재발 여부 및 재발까지의 기간은 유의한 상관 관계가 없었다. 결론적으로, 경동맥화학색전술 후 종양 괴사율은 크기가 3cm 이상이고, 동맥조영술 상 간외 공급 혈관이 있는 경우, 피막이 없는 경우, 병리학적 성장 양상이 침윤형인 경우, 분화도 등급이 높은 경우에 높았다. 그러므로 영상 진단, 혈관조영술 및 병리학적 소견 등 으로 치료 효과 즉 괴사율을 예측할 수 있다. -------------------- 핵심되는 말 : 간세포암, 경동맥화학색전술, 간절제술, 괴사율 [영문] In this study, the factors affecting tumor necrosis after transarterial chemoembolization (TACE) were evaluated. Fifty-five tumors of 52 patients (44 men and 11 women) whose mean age was 49 years, with hepatocellular carcinoma (HCC) that diagnosed by surgical resection were included. Imaging evaluation included the size of tumor, border (well-defined/ ill-defined), the presence of capsule and vascular invasion in pre-TACE studies, using CT or MRI. Pathological evaluation included vascular invasion of tumor, supplying arteries (intrahepatic/ extrahepatic), selected vessels of embolization (lobar/ segmental / subsegmental), the amount of anti-cancer drugs and embolic materials, the use of gelfoam or not, and the presence of AP or AV shunt during TACE. Resected specimens were evaluated in the degree of necrosis (% of tumor), growth pattern, degree of differentiation (Edmondson-Steiner's grade), and presence of capsule. The relationship of variable radiological and pathological factors with necrosis was evaluated statistically in this study. The size of tumors was 1~ 12cm in the diameter (mean 5.3cm). The frequency of preoperative TACE was once in 45 tumors, twice in 10 tumors. The period between TACE and resection was variable from 6 to 485 days (mean 75.5 days). The degree of necrosis was 5 ~ 100% (mean 79.5%). The factors, which showed statistically significant decrease of the degree of necrosis, were size over 3cm, presence of extrahepatic aretrial supply, infiltrative growth pattern, poorer differentiation of HCCs, and absence of capsule. The recurrence or the time interval of the recurrence showed no significant relationship with degree of tumor necrosis. In conclusion, the degree of tumor necrosis was significantly lower in the cases with following features; tumor size greater than 3cm, with extrahepatic supplying vessels in arterial angiography, without encapsulation, infiltrative growth pattern and poorer differntiation in pathological findings. Therefore the effect of treatment with transarterial chemoembolization can be predicted by radiological diagnosis including angiography in conjunction with pathological evaluation.ope

Pedagogical examination of the understanding of the concepts of functions and inverse functions

학위논문(석사)--서울대학교 대학원 :수학교육과,2005.Maste

삼투조절을 위한 온도응답성 물질의 개발과 수처리로의 응용

학위논문 (박사)-- 서울대학교 대학원 : 자연과학대학 화학부, 2018. 2. 이연.Signal-responsive materials are defined as materials which show an abrupt change in physical or chemical properties by external stimuli such as temperature, light, pH, magnetic field, electric field and so on. They have gained a lot of attention since their application area is broad. In order to exhibit the signal-responsive character it can be achieved by designing the molecular structure. Amongst a variety of signal-responsive materials thermo-responsive materials have been extensively investigated due to their easy treatment of stimuli. Thermo-responsive materials are categorised as two different materials, lower critical solution temperature (LCST) and upper critical solution temperature (UCST) materials. LCST materials are miscible with a certain solvent below a certain temperature but immiscible above the certain temperature. Whereas UCST materials are insoluble with a certain solvent below a certain temperature, while they are soluble above the temperature. A sudden change in solubility can derive the change in osmotic pressure in a solvent. It can be further applied for water treatment system using water as a solvent. The phase transition phenomenon can be explained by the Gibbs free energy equation when water and thermo-responsive materials are mixed together. Gmix = Hmix – TSmix (Gmix : the Gibbs free energy of mixing, Hmix : the enthalpy of mixing, Smix : the entropy of mixing, T : temperature) When the Gibbs free energy of mixing (Gmix) becomes zero at a certain concentration, the temperature can be defined as the phase transition temperature, either LCST or UCST. T =HmixSmix (Gmix = 0, at a certain concentration) The enthalpy term (Hmix) and the entropy term (Smix) are closely related to the phase transition temperature and dependent on the balance between hydrophobicity and hydrophilicity of the molecule. By controlling the hydrophobicity and the hydrophilicity of the molecule the thermo-responsive character is decided. Various kinds of thermo-responsive materials are synthesised for water treatment system through the systematic design of the thermo-responsive materials. Amongst water treatment systems including thermal distillation, reverse osmosis and so on, forward osmosis (FO) system has been intensively studied. Since FO system has advantages such as less membrane fouling and energy conversion efficiency, FO is recently obtaining a significant amount of attention. FO consists of two different solutions, a draw solution and a feed solution, and a semi-permeable membrane and utilises the difference in osmotic pressures between the two different solutions by osmosis. In a drawing process, the draw solution which has a higher osmosis pressure can draw water from the feed solution through the membrane. Subsequently, draw solutes should be separated in the diluted drawn solution so that water can be obtained. Thus, draw solutes are significantly important in FO system. As an ideal draw solute, it is necessary to satisfy high osmotic pressure, easy separation, regeneration, reusability and so on. One of the most extensively investigated FO system is ammonia/ammonium bicarbonate (NH3/NH4HCO¬3) FO system which meets some of the criteria. However, the NH3/NH4HCO3 system consumes a high thermal energy, causes a membrane damage and involves a complex regeneration process. Hence, it is necessary to develop a new draw solute which can exhibit high osmotic pressure, uses a small amount energy for the separation process and involves negligible membrane damage. As an alternative, FO system with thermo-responsive materials can be established. Thermo-responsive draw solutes should generate high osmotic pressure, and be separated from water with mild temperature change. In addition, the draw solution should be neutral in order not to damage the membrane. A previously studied thermo-responsive material, branched polyethylenimine was acquired by a simple acylation. Since acylated branched polyethylenimine (acyl-b-PEI) is a polymer with high molecular weight, it is unable to show high osmotic pressure based on the vant Hoff equation. In order to overcome such limitation carbon dioxide (CO2) gas was injected into the polymeric solution because tertiary ammine moieties in the polymer can absorb the hydrated form of CO2, bicarbonate ion, HCO3-. Bicarbonate-containing polymeric draw solution shows high enough osmotic pressure to draw water from seawater. After the drawing process, thermal energy was applied and the phase separation occurred and the absorbed CO2 was released. Even though CO2-combined acyl-b-PEI FO system can be applied for desalination, it is still required to develop a draw solute which can generate high enough osmotic pressure to draw water from highly concentrated wastewater. Hence, ammonium iodide salts with lower molecular weight are further investigated. Ammonium iodide salts are UCST materials and can generate high osmotic pressure due to the ionic character as well as low molecular weight. By controlling the molecular structure a series of ammonium iodide salts can be synthesised. A various ammonium iodide salts are investigated and some of the suitable salts are selected and subsequent FO process is conducted with the extracted wastewater from a factory. In conclusion, this dissertation can give a guideline to develop thermo-responsive materials with the required criteria by fine tuning the molecular structure. In addition, with the implementation of desalination and wastewater treatment, I hope that the introduced thermo-responsive draws solutes have high potential and can be applied for the feasible water treatment system.Part Ⅰ. Development of Lower Critical Solution Temperature Phase Transition Materials for Controlling the Osmotic Pressure 1 1. Abstract 2 2. Introduction 3 3. Experimental Section 6 3.1. Materials 6 3.2. Preparation of Bu-PEI and Bu-Val-PEI 6 3.3. Measurement of LCST phase transition 8 3.4. Measurement of CO2 absorption and release 8 3.5. Measurement of the FO water flux 9 4. Results and Discussion 10 4.1. Synthesis of LCST polymers 10 4.2. LCST phase transition 10 4.3. Temperature-driven CO2 absorption and release 11 4.4. FO water flux of Bu-PEI and Vu-Val-PEI solutions 13 5. Conclusions 17 6. References 19 Part Ⅱ. Development of Upper Critical Solution Temperature Phase Transition Materials for Controlling the Osmotic Pressure 33 1. Abstract 34 2. Introduction 36 3. Experimental Section 41 3.1. Materials 41 3.2. Synthetic draw solutes 42 3.3. Measurement of UCST phase transition 44 3.4. Measurement of osmolality 45 3.5. Measurement of the FO water flux 45 3.6. Measurement of reverse solute flux 46 3.7. Thermal stability of draw solutes 47 3.8. Cytotoxicity assay 47 3.9. Post-treatment of water-rich layer 48 4. Results and Discussion 50 4.1. Systematic design and synthesis of draw solutes 50 4.2. UCST phase-transition behaviour of ammonium iodide salts 55 4.3. Change in osmolality through the UCST phase transition 59 4.4. Selection of suitable draw solutes for FO 63 4.5. FO waster flux of HM8I and HM10I solutions 64 4.6. Reverse solute flux of draw solutes 67 4.7. Post-FO water treatment 69 4.8. Stability and toxicity of draw solutes 71 5. Conclusions 73 6. References 75 List of Publications 102 Abstract (국문초록) 104Docto

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