• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.585-591
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• 2014

The primary objective of the current work is to predict speed performance of the medium patrol boat over $F_N=0.5$ employing experimental materials based on the CFD before model tests. In other words, the predicted brake powers according to ship speeds are assessed satisfying the main engine capacity. The subject ships are selected the two different stern hull forms. The flow computation are conducted considering free surface and dynamic trim using a commercial CFD code(STAR-CCM+). The resistances of the bare-hull are obtained from CFD. Wave patterns, pressures and limiting streamlines on the hull and velocity distribution in the propeller plane for the two hull forms are compared using CFD. The effective powers of the object ships are assessed based on CFD. Resistance increase according to the attached appendages and quasi-propulsive efficiency are employed the experimental datas. Speed performance prediction method concerning high speed vessels like a medium patrol boat is developed employing CFD and experimental data.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.53-64
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• 2018

In this study, computational simulation was performed to investigate the characteristics of air/fuel mixing according to the shape of the injector exit when the transverse jet was injected into a supersonic flow. Non-reacting flow simulation was conducted with fixed mass flow rate and the same cross-sectional area. To validate the results, free stream Mach number and jet-to-crossflow memetum ratio are set to 3.38 and 1.4, respectively, which is same as the experimental condition. Further, separation region, structure of the under-expended jet, jet penetration height, and flammable region of hydrogen for five different injectors compared.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.752-757
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• 1997

Crude papain extracted at optimum condition was purified with an ethanol precipitation method. Four factors of protein recovery method were optimized by response surface methodology (RSM) and the function was expressed in terms of a quadratic polynomial equation. Adequacy of the model equation for optimum response values was tested and optimum conditions of protein recovery were 38.2 mg/mL of protein, ethanol concentration of 40% and precipitation temperature of $-8^{\circ}C$. The experimental value (68.97%) for recovery yield was closed to the predicted value (77.28%) under these conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.12
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• pp.1027-1034
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• 2014

The shear stress on a surface due to the thin film fluid flow is an important issue. In case of a rotating disk, the fluid is delivered to the edge of the disk by centrifugal force, which acts as a body force on the fluid. Wear of a surface is affected by the shear stress acting on the surface and curvature. In this study, we utilize computational fluid dynamics software to model the ratio of curvature and local shear stress on solid surfaces. The key goal of the study is to determine an optimized curvature for the thin film fluid flow on a solid surface in order to minimize the local shear stress affecting the wear of this surface. Our results on the effects of curvature will be utilized for the design of devices that utilize thin film fluid flow on a solid surface, such as rotating-disk spray systems and thin film coating.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.39-46
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• 2023

In this study, the dynamic behavior of friction bearings of PSC (Pre-Stressed Concrete) box train continuous bridge was numerically analyzed at 10 km/h intervals up to 600 km/h according to the increasing speed of the next-generation high-speed train. A frame model was generated targeting the 40-meter single-span and two-span continuous PSC box bridges in the Gyeongbu High-Speed Railway section. The interaction forces including the inertial mass vehicle model with 38 degrees of freedom and the irregularities of the bridge and track were considered. It was calculated the longitudinal displacement, cumulative sliding distance and displacement speed of the bridge bearings at each running speed so that compared with the dynamic behavior trend analysis of the bridge. In addition, long-term friction test standards were applied to evaluate the durability of friction plates.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.26-32
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• 2001

In this paper, elastic responses of a floating structure in waves with a breakwater are presented. The method of source-dipole distribution is used to analyze the velocity potentials for the fluid region. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The model for present calculation is a floating plate with an length of 1000m and the hydroelastic responses for a floating structure with a straight breakwater are shown. The effects of distance between breakwater and structure, bending rigidity and relative length of regular waves are examined.

• The Korean Journal of Zoology
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• v.36 no.2
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• pp.264-275
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• 1993

서식수 염분농도의 변화에 따른 guppy(Poecilia reticulotus) 아가미 상피내 염소세포(chloride cell)의 미세구조적 변화를 전자현미경으로 관찰하고, 특히 증가하는 염분농도에 따라 주요변화를 보여주는 염소세포내 미토콘드리아와 tubular system의 면적을 영상 분석기로 측정하여 다음의 결과를 얻었다. 염소세포는 주로 guppy 아가미궁의 일차 총판상피에 위치하는데 담수에서는 하나씩 독립적으로 존재하며 자유면이 apical pit를 형성하여 외부환경에 노출되는 반면. 서식수의 염분농도가 증가하면 여러개의 염소세포들이 다세포복합체를 형성하고 이 세포들의 자유면이 함께 하나의 apical pit를 구성하게 된다. 서식수의 염분농도가 증가함에 따라 염소세포내의 미토콘드리아와 tubular system은 점점 더 조밀하게 분포하는 것으로 관찰되었다 염소세포의 단위면적당 미토콘드리아가 차지하는 면적은 서식수가 담수(0%의 염분농도)인 경우는 24$\pm$5%였고, 1%에서는 26$\pm$5%, 2%에서는 33$\pm$7% 그리고 해수(3.2% 염분농도)에 적응된 경우는 42$\pm$7%로 담수환경의 것과 비교하여 약 18%까지 증가하였다 또한 염소세포의 측면과 기저측 세포막 함입의 결과로 형성되는 tubular system은 세포의 단위면적당 차지하는 면적이 담수에 적응된 개체들에서 38$\pm$9%였고 서식환경의 염분농도에 따라 점차 증가하다가 해수에서는 61$\pm$9%로 약 16%까지 높아졌다.

• Korean Journal of Food Science and Technology
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• v.12 no.4
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• pp.324-327
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• 1980

The seeds of Torreya nucifera, which were shown to contain high level of oil, were characterized to evaluate their possible utilization as oil source. Oil was extracted by compression from the seeds and its physico-chemical properties and, total fatty acid composition were determined. The results are summarized as follows: 1. Proximate components of the seeds were shown to be: moisture, 12.3% ; crude protein, 9.46%; crude fat, 54.29 %; fiber, 5.28 %; ash, 2.13%. 2. Physico-chemical characteristics of the seed oil were determined as follows: specific gravity 0.92, refractive index 1.470, iodine value 127, saponification value 182.2, acid value 9.5, ester value 172.7. 3. The major fatty acids of the total lipids were linoleic (46.77%), oleic (31.68%) and palmitic acid (6.92%).

• Journal of Korean Home Economics Education Association
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• v.26 no.3
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• pp.69-89
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• 2014

The purpose of this paper was to understand the outlines of 1) common and free curricula implemented by the first pilot schools and 2) Home Economics related programs from both curricula. This study analyzed the 42 reports from the first pilot schools which implemented the free learning semester in 2013. The results showed that more than half of schools set two or more emphasis models of the free learning semester. In 15 out of 28 schools, the lesson hours of Home Economics were reduced by one to three hours. Various common curricula were implemented in many aspects of teaching-learning methods, curriculum, evaluation, and subject related career lessons. Free curriculum was implemented in four areas such as career exploration, student optional program, club activity, and art sports activity. In common curriculum, Home Economics was carried out in 17 out of 39 schools. The Home Economics class included subject related career lessons and improvement of teaching- learning methods. Various interesting activities and programs as a free curriculum were implemented in career exploration, students' optional program, and club activities in 38 schools. The most frequently implemented was the activity program related to food and nutrition. Further research was proposed to develop students' optional programs related to Home Economics subject, responding to their needs.

• Journal of The Korean Association For Science Education
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• v.38 no.4
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• pp.541-553
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• 2018

The purpose of this study is to explore the relationship between epistemic goals, epistemic considerations and complexity of reasoning of science high school students in an open inquiry and to explore the context on how open inquiry compares with the characteristics of an authentic scientific inquiry. Two teams were selected as focus groups and a case study was conducted. The findings are as follows: First, the contexts, such as 'sharing the value for the phenomenon understanding, reflection on the value of the research, task characteristics that require collaboration and consensus, and sufficient communication opportunities,' promote epistemic goals and considerations. On the other hand, contexts such as 'lack of opportunity for critical review of related literature and environmental constraints' lowered epistemic sides. Second, epistemic goals and considerations influenced the reasoning complexity. The goal of 'scientific sense making' led to reasoning that pose testable hypotheses based on students' own questions. The high justification considerations led to purposely focusing attention to the control designs and developing creative experimental know-how. The high audience considerations led to defending their findings through argumentation and suggesting future research. On the other hand, the goal of 'doing the lesson' and the low justification considerations led to reasoning that did not interpret the meaning of the data and did not control the limit of experiment. The low audience considerations led to reasoning that did not actively defend their findings and not suggest future research. The results of this study suggest that guidance should provide communication and critical review opportunities.