Computation of Flows Around a High Speed Catamaran

Kwag, Seung-Hyun The Korean Society of Mechanical Engineers 2001 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.15 No.4

A numerical study is carried out to clarify the characteristics of flow fields and breaking phenomena around a high speed catamaran hull advancing on calm water. Computations are carried out for Froude numbers between 0.2 and 1.0 and for ratios of the distance between hulls to the catamaran length varying between 0.2 and 0.5 for a mathematically defined Wigley hull. A Navier-Stokes solver which includes the nonlinearities of free surface conditions is employed. Computations are performed in a rectangular grid system based on the Marker & Cell method. For validation, present computation results are compared with existing experimental results. As an application, the results of the displacement catamaran are used for the breaking analysis.

Application of Bayesian statistics to seismic probabilistic safety assessment for research reactor

Kwag, Shinyoung,Oh, Jinho,Lee, Jong-Min Elsevier 2018 Nuclear engineering and design Vol.328 No.-

<P><B>Abstract</B></P> <P>Nuclear facilities are susceptible to the damage due to earthquake hazards. The recent strong earthquake events show the need to explore scenarios in which the expected seismic hazard exceeds a design basis earthquake. In this regard, the seismic probabilistic safety assessment (SPSA) methodology has been developed and utilized to access the overall risk to a nuclear power plant. However, it remains challenging to deal with various uncertainties, accurately to describe correlated events, to accommodate newly observed data and to consider severe accident scenarios within the current framework. In order to overcome such challenges and take advantage of the merits of recent systems analysis concepts, this paper explores a SPSA approach by integrating the current SPSA framework with a Bayesian network and Bayesian inference instead of utilizing the standard fault tree-based technique. The proposed approach enables one to account for what are known as Aleatory and Epistemic uncertainties, to consider the correlated events, to incorporate the additional data and to conduct vulnerability assessments in an accident condition. The proposed Bayesian-based method is demonstrated by its application to a research reactor as an example. Several case studies are conducted to demonstrate how additional information such as correlated events and newly observed data changes the system-level fragility and risk. In addition, a critical scenario is investigated in a situation in which an accident has occurred for a vulnerability assessment beyond a design-basis event. Consequently, it is shown that the proposed approach provides an enhanced framework for risk assessments at nuclear facilities under earthquake hazards. This framework is ultimately expected to be extended to effective plans to mitigate system-level risk and to enhance decision support for risk-informed designs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This study explores a Bayesian-based approach for seismic PSA of research reactor. </LI> <LI> Incorporation of a Bayesian network enables considering correlated events. </LI> <LI> It is also capable of conducting beyond-design-vulnerability assessments. </LI> <LI> Bayesian inference makes it feasible to evaluate real-time risk. </LI> </UL> </P>

A Study on the Influence of Choice Properties of Food Carving Decoration Lecture on Recommended Intention and Revisiting Intention

Kwag, Myung Sug,Kim, Jin Soo Kyung Hee University Management Research Institute 2020 Asia pacific journal of business review Vol.5 No.1

This paper examines the effect of the choice properties of food carving decoration lectures on the recommendation and revisiting intention. As the culinary industry grows, consumers seek not only the value of satiety through food but also the value of aesthetics. They perceived satisfaction from the taste and appearance of the food as well as the interior of the restaurant and the service. Food carving is an important means of fulfilling consumer satisfaction value which is ever-changing. This study attempts to analyze the relationship between the choice properties of food carving lectures and the course recommendation and revisiting intention. This study hypothesis was formulated and the survey was conducted on 125 respondents who had experienced food carving lectures. The reliability and validity of measurement items were verified through Cronbach's Alpha and factor analysis. As a result, all measurement items showed no abnormality. The results of the analyses are as follows. The education satisfaction, education commitment, and brand image, the choice properties of food carving decoration lecture, were found to have a positive effect on the recommendation intention. The results also showed that the education commitment and brand image of food carving decoration lectures were positively associated with revisiting intention. Lastly, the implications of these findings were suggested and for future research were discussed.

Obstacle Awareness and Collision Avoidance Radar Sensor System for Smart UAV

Kwag, Young K.,Hwang, Kwang Y.,Kang, Jung W. The Korean Society for Aeronautical and Space Scie 2005 International Journal of Aeronautical and Space Sc Vol.6 No.2

In this paper, the critical requirement for obstacle awareness and avoidance is assessed with the compliance of the equivalent level of safety regulation, and then the collision avoidance sensor system is presented with the key design parameters for the requirement of the smart unmanned aerial vehicle in low-altitude flight. Based on the assessment of various sensors, small-sized radar sensor is selected for the suitable candidate due to the real-time range and range-rate acquisition capability of the stationary and moving aircraft even under all-weather environments. Through the performance analysis for the system requirement, the conceptual design result of radar sensor model is proposed with the range detection probability and collision avoidance mode is established based on the time-to-collision, which is analyzed by collision scenario.

The Relation between Electrical Resistivity and the Microstructure in the Al-Mn Alloys

Kwag, Young Jik 수원대학교 기초과학연구소 1997 基礎科學論文集 Vol.6 No.-

합금의 미세구조를 결정짓는 중요한 세 가지 요소는 고용체 속에 들어 있는 고용체 원소의 밀도, 석출물의 크기와 량, 그리고 각종 격자 결함이다. 연구에 사용된 알루미늄 망간 합금 속에는 1.25%의 망간이 들어 있는데 이 망간은 열처리 온도와 시간에 따라 고용체 속에 녹아 있기도 하고, 석출물로 석출하기도 한다. 열처리 온도와 시간을 이용하면 석출하는 알루미늄망간(Al_6Mn)상의 크기와 밀도를 조절할 수 있다. 1.27㎝ 두께로 스트립 캐스팅된 상태로 입수한 시료는 적당한 크기로 잘라 세 가지 다른 온도에서 2시간 열처리 한 후에 전기전도도와 강도를 측정하고 전자현미경(TEM)으로 미세구조를 측정하였다. 이 시료들은 다시 냉간 압연하여 격자 결함을 증가시킨 후 서로 다른 온도에서 열처리하여 전기전도도와 미세구조를 조사하였다. 이 실험의 결과 금속의 비저항은 고용체 속에 들어 있는 망간 원소의 량에 의해 결정되고 석출입자의 크기나 량, 그리고 격자결함에는 큰 영향을 받지 않는 것으로 나타났다.

A Macrocyclic Nickel(II) Complex Salt Containing Six-Coordinate Nickel(II) Ions in a Different Coordination Environment

Kwag, Jin-Suk,Park, Han-Young,Lough, Alan J.,Kim, Ju-Chang Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.1

Co-Ni alloy nanowires prepared by anodic aluminum oxide template via electrochemical deposition.

Kwag, Yong-Gyu,Ha, Jong-Keun,Kim, Hye-Sung,Cho, Hyoung-Jin,Cho, Kwon-Koo American Scientific Publishers 2014 Journal of Nanoscience and Nanotechnology Vol.14 No.12

<P>The alloy nanowires are more prospective magnetic and shape memory materials. Fabrication of binary or more alloy nanowires using electrochemical deposition process is generally challenging due to the different synthesis conditions of individual elements. In the present work, binary NiCo alloy nanowire arrays have been fabricated by electrochemical deposition using anodic aluminum oxide template medium technique. The optimum conditions (temperature, voltage and time) for synthesis of NiCo alloy nanowire array were achieved based on the ideal experimental conditions of single Ni and Co nanowire arrays. The synthesized NiCo alloy nanowire arrays were characterized by X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray spectrometer. The amorphous NiCo alloy nanowires were crystallized by annealing of 800 degrees C for 1 hour in argon atmosphere. The controlled composition of electrolyte provided to achieve a uniformly distributed chemical composition of Ni and Co (49.26:50.74) in nanowires.</P>

Facile synthesis of multilayered polysaccharidic vesicles

Kwag, D.S.,Oh, K.T.,Lee, E.S. Elsevier Science Publishers 2014 Journal of controlled release Vol.187 No.-

In this study, we developed facile synthesis method of multilayered polysaccharidic vesicles (hereafter termed 'mPSVs') using polysaccharides such as starch, hyaluronate (HA), and glycol chitosan (GC) via simple chemistry and using enzymatic reactions among polysaccharides. The enzymatic degradation of the HA shell by hyaluronidase (HYAL) enzyme contributed to accelerate the release of protein/peptide from the mPSVs. The mPSVs containing folate ligand and apoptotic cell death-inducing D-(KLAKLAK)<SUB>2</SUB> peptide were effectively accumulated in in vivo KB tumor cells, primarily owing to passive tumor penetration via the enhanced permeability and retention (EPR) effect and active targeting via specific binding to folate receptors expressed on KB tumor cells. These mPSVs resulted in a significant increase in the in vivo tumor inhibition. This vesicle system is expected to exhibit great potential as an advanced platform technology for biomedical applications involving small molecular drugs with protein/gene targets.

Arterial hyperintensity on BLADE fluid-attenuated inversion recovery images (FLAIR) in hyperacute territorial infarction: comparison with conventional FLAIR.

Kwag, Eujean,Lim, Soo Mee,Park, Ji Eun,Chae, In Hye Springer International 2014 EUROPEAN RADIOLOGY Vol.24 No.9

<P>To evaluate the utility of BLADE fluid-attenuated inversion recovery images (FLAIR) magnetic resonance (MR) imaging compared to conventional FLAIR for the detection of arterial hyperintensity (AH) in hyperacute territorial infarction.</P>

Biodistribution and Hepatic Metabolism of Galactosylated ^(111)In-Antibody-Chelator Conjugates : Comparison with ^(111)In-Antibody-Chelator Conjugates ^(111)In-표지 항체와의 비교연구

Kwag, Dong Suk,Lee, Jeatae,Jeong, Kyu Sik,Ha, Jeong Hee,Ahn, Byeong Cheol,Lee, Kyubo,Paik, Chang H. 대한핵의학회 2003 핵의학 분자영상 Vol.37 No.6

목적 : 종양의 진단과 치료에 널리 이용되고 있는 단클론항체를 수용체에 결합하는 수송체로 이용할 수 있는지에 대한 가능성 여부를 평가하기 위하여, 간의 asialoglycoprotein 수용체에 결합할 수 있는 갈락토즈접합 단클론항체를 ^(111)In로 표지하여 체내에서의 분포와 간을 중심으로 한 체내대사를 분석하였고, 그 결과를 갈락토즈를 접합하지 않은 ^(111)In표지 항체와 비교하였다. 재료 및 방법 : 인체 림프구성백혈병 세포에 대한 T101 단일클론항체를 cyclic DTPA dianhydrate(DTPA) 나 2-p-isothiocy-anatobenzyl-6-methyl-DTPA(1B4M) 로 접합하고 갈락토즈를 붙인후 ^(111)In으로 표지하였다. 생쥐와 흰쥐에서 갈락토즈를 접합한 화합물과 접합하지 않은 화합물의 체내분포와 간대사를 비교분석하였다. 결과 : ^(111)In 표지 T101항체와 갈락토즈 접합체는 투여량의 대부분이 10분 이내에 간에 섭취되었다. DTPA 접합자를 사용한 경우 1B4M 접합자를 사용한 경우보다 간에 오랫동안 저류되어 주사 후 44시간 간 섭취율이 각각 55%와 20% 였다. 이 기간동안의 DTPA 화합물의 방사성 대사산물은 24%가 소변으로 17%가 대변으로 배설되어 유사하였으나 1B4M 화합물은 68%가 대변으로 8%가 소변으로 배설되어 배설경로에 차이가 있었다. 1B4M 화합물을 주사후 3시간의 담즙과 간 현탁액을 HPLC로 분석한 결과 IgG와 저류시간(Rt)이 같은 첫 절정에 35%, 유리 ^(111)In과 유사한 절정의 Rt에 65%가 관찰되어 대사산물이 빠르게 답즙으로 배출됨을 알 수 있었고, DTPA 화합물 주사후 3시간 대사산물은 90%가 ^(111)In-DTPA와 유사한 Rt의 절정을 보였다. 그러나 대변의 ^(111)In의 축적량은 낮아 DTPA 접합화합물은 담도를 통한 빠른 배설이 일어나지 않음을 알 수 있었다. 결론 : 단일클론항체에 갈락토즈를 접합한 경우 보통의 항체에 비하여 간 섭취가 많고, 간에서의 대사가 촉진된다. 이 경우 사용되는 접합자의 선택에 따라서 대사산물의 성분이 달라지고 간에서의 제거도 차이가 있다. 이러한 대사의 차이접은 향후 종양세포나 조직의 탐색에 이용할 방사능 표지 항체의 제조에 응용될 수 있을 것이다. Purpose : To evaluate the use of monoclonal antibody (MoAb) as a carrier of the receptor-binding ligand, the receptor mediated uptake into liver and subsequent metabolism of ^(111)In-labeled galactosylated MoAb-chelator conjugates were investigated and compared with those of In labeled MoAb. Materials and Methods : T101 MoAb, IgG_(2) against human lymphocytic leukemic cell, conjugated with cyclic DTPA dianhydride (DTPA) or 2-p-isothiocyanatobenzyl-6-methyl-DTPA (1B4M) was galactosylated with 2-imino-2-methoxyethyl-1-thio-β-D-galactose and then radiolabeled with ^(111)In. Biodistribution and metabolism study was performed with two ^(111)In-conjugates in mice and rats. Results : ^(111)In-labeled T101 and its galactosylated conjugates were taken to the liver by the time, mostly within 10min. However DTPA conjugate was retained longer in the liver than the 1B4M conjugate (55% vs 20% of injected dose at 44hr). During this time, the radiometabolite of DTPA conjugate was excreted similarly into urine (24%) and feces (17%). The radiometabolite of 1B4M was excreted primarily into feces (68%) rather than urine (8%). Size exclusion HPLC analysis of the bile and supernatant of liver homogenate showed two peaks, the first (35%) with the retention time (Rt) identical to IgG and the second (65%) with Rt similar to free ^(111)In at 3hr post-injection for the 1 B4M conjugate, indicating that the metabolite is rapidly excreted through the biliary system. In contrast to DTPA conjugate, the small ^(111)In-DTPA-like metabolite was the major radioindium component (90%) in the liver homogenate as early as 3 hour post-injection, but the cumulative radioindium activity in feces was only 17% at 44 hour, indicating that the metabolite from DTPA conjugate does not clear readily through the biliary tract. Conclusion : The galactosylation of the MoAb conjugates resulted in higher hepatocyte uptake and enhanced metabolism, compared to those without galactosylation. Metabolism of the MoAb-conjugates is different between compounds radiolabled with different chelators due to different characteristics of radiometabolites generated in the liver.