• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.9-9
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• 2000

액체 램제트 엔진의 V형 유입구에 3개의 안내깃이 있은 경우에 대하여 유동 해석을 수행하였다. 수치해석에 앞서 본 연구에서는 ONERA에서 발표한 고체 램제트 연소기에 대한 실험 결과를 유동 해석 결과와 비교하여 해석의 정확성을 검증하였다. 안내깃에 의하여 연소실로 유입되는 공기는 유입구 곡관에서 효율적인 흐름을 유지할 수 있고 분사되는 연료의 분포도 제어될 수 있다. 안내깃의 두께가 큰 경우 자칫 유입되는 공기의 흐름을 방해하는 장애물의 역할을 할 수 있으므로 두께의 변화에 대한 영향도 계산하였으나 선정된 안내깃에 의한 연소실에서의 유동특성 변화는 적은 것으로 나타났다. 입구조건을 균일 유동으로 주고 해석한 결과, 연소실에서의 유동은 안내깃의 유무에 따라 큰 영향을 받지 않았다. 그러나 흡입구로 유입되는 공기의 속도 분포는 다양한 비행조건에서 균일하지 않기 때문에 주 유동을 방해하지 않는 안내깃의 설치는 연소실에서의 좀 더 안정된 화염의 생성을 위해 필요하다.

• The KIPS Transactions:PartA
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• v.14A no.5
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• pp.255-262
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• 2007

Physically-based researches on simulating helicopter motions have been achieved in the field of aeronautics, aerodynamics and others. These results, however, have not been appled in the computer graphics area, mainly due to their complex equations and heavy computations. In this paper, we propose a dynamics model of helicopter rotor blades, which would be easy to implement, and suitable for real-time simulations of helicopters in the computer graphics area. Helicopters fly by the forces due to the collisions between air and rotor blades. These forces can be interpreted as the impulsive forces between the fluid and the rigid body. Based on these impulsive forces, we propose an approximated dynamics model of rotor blades, and it enables us to simulate the helicopter motions using existing rigid body simulation methods. We compute forces due to the movement of rotor blades according to the Newton's method, to achieve its real-time computations. Our prototype implementation shows real-time aerial navigation of helicopters, which are murk similar to the realistic motions.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.745-747
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• 2023

깃허브는 개발자의 명함이라는 말이 있듯, 많은 수의 개발자들이 깃허브를 활용해 자신의 개발 이력과 프로젝트들을 관리한다. 이를 위해 기존의 깃허브 정보 요약 서비스들이 제공되어졌으나, 정보 공유의 불편함과 많은 정보를 담지 못한다는 불편함이 존재했다. 본 논문에서는 이러한 불편함을 해소하기 위해 서버 기반의 깃허브 웹 명함 제작 및 멀티플랫폼에서의 서비스를 기반으로 한 효율적인 개발자 명함 생태계 구축을 제안한다. 본 서비스에서는 Next.js 기술을 활용한 한 명함 제작 및 웹, 앱 클라이언트를 통한 명함 관리 기능을 제공한다. Github oauth를 통해 인증된 정보를 바탕으로 Next.js를 활용해 사용자에 대한 정보를 정해진 형식으로 요약한 명함을 제작한다. 제작된 명함은 웹 / 앱 플랫폼을 기반으로 관리되며, 추가적으로 명함의 공유 및 저장 기능을 수행한다. 이를 통해, 명함 공유를 바탕으로 한 개발자 네트워크 형성을 목표로 한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.21-25
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• 1998

탈황설비 배관내 연소가스의 삼차원 유동장에 대한 전산해석을 수행하였다. 복잡한 형상으로 주어진 배관내의 유동장 특성을 관찰하고 압력손실을 계산하였다. 특히 안개깃의 설치유무에 따른 유동장 특성 변화 및 압력손실 감소효과를 집중적으로 고찰하였다. 안내깃의 설치에 따라 유량배분이 적절하게 되고 압력손실이 현저하게 줄어듬을 알 수 있었다. 배관에서의 압력손실을 계산하여 배관설계 및 송풍기 용량 산정의 적절성을 확인할 수 있었다.

• The Transactions of the Korea Information Processing Society
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• v.13 no.8
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• pp.374-381
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• 2024

Documentation repositories on GitHub are used to share information that is helpful in performing various tasks. Popular documentation repositories have an advantage in attracting contributors who can help manage and extend documentation repository. Therefore, it is important to understand the characteristic of documentation repositories helpful to obtain popularity for developing strategies attracting attention of users. This paper presents a study on GitHub documentation repositories. To conduct the study, we collected 566 documentation repositories from GitHub and manually categorized their topic into 30 topics. Based on the stargazer score of the collected documentation repositories, we divided the collected documentation repositories into popular and unpopular documentation repository groups and investigated the topics in the popular documentation group. Then we statistically examined the differences in README characteristics of the popular and unpopular documentation repository groups. As a result, we found that the studied documentation repositories have 23 popular topics. We also found that the popular and unpopular documentation repository groups have differences in 5 README characteristics. The result of our study indicates that what documentation repository become popular in GitHub.

• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.161-171
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• 2014

In this paper the flow dynamics of the flue gas equipment in the desulfurization system was numerically analyzed by simulating the problems for the turbulent and combustion flow from Induced Draft Fan(I.D.Fan) outlet to Booster Up Fan(B.U.Fan) inlet using the commercial CFD software of CFD-ACE+ in CFDRC company for Computational Fluid Dynamic Analysis. The guide vane of this section was examined for the minimum pressure loss and the uniform flow dynamic to B.U.Fan with the proper velocity from I.D,Fan exit to B,U,Fan inlet section at the boiler both the maximum continuous rating and the design base. The guide vanes at I,D.Fan outlet and B.U.Fan inlet were removed and modified by numerical simulation of the CFD analysis. The flue gas at the system had the less pressure loss and the uniform flow dynamics of the flow velocity and flow line by comparing with the old design equipment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2171-2180
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• 1991

An analysis model for off-design performance of radial inflow turbines with or without variable area guide vane is developed, where two important factors in loss models, total pressure ratio between variable area guide vane exit and scroll casing inlet and rotor loss coefficient are determined without experimental data. The analysis results show that the predicted trends with or without variable area guide vane are consistent with the experimental observations. The comparison of present method with the well-known NASA off-design performance analysis program shows that the mass flow rate and static efficiency by present analysis are in good agreement with those by the NASA program. Therefore, this method can be used to predict off-design performance of radial inflow turbines with validity of the loss models used by present analysis.

• Korean Journal of Plant Taxonomy
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• v.44 no.4
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• pp.257-260
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• 2014

While preparing a floristic study of Korean Pteridophytes, we discovered the following two unrecorded species from Jeju Island: Cyclosorus penangianus (Hook.) Copel. and Pteris fauriei Hieron. C. penangianus can be distinguished from other Korean congeners of the genus Cyclosorus by having exindusiate sori, toward with sinus of ultimate segments of veinlets more than 4. P. fauriei can be distinguished from other Korean congeners of the genus Pteris by having ultimate segments with entire margins, veins reaching to leaf margin and membraneous petiolar scales.

• Journal of Energy Engineering
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• v.10 no.4
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• pp.335-341
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• 2001

Pressure pulsations generated by the blade-tongue interaction induce vibration of the piping systems and the structure connected to pumps, resulting in the severe noise and fatigue fracture. Experiments were made on the natural frequencies of liquid columns in piping systems with a single suction, single stage, centrifugal volute pump. Experimental results show that the natural frequencies of the liquid columns in the pump piping systems depend on the dimensions of the pipes and the impeller shapes, and are not affected substantially by the rate of discharge and the rotating speed of the pump.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.207-214
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• 2015

The preliminary design of a radial inflow turbine using R134a as the working fluid at 5 kW of power for application to ocean thermal energy conversion (OTEC) is performed to obtain the trends for the efficiency and geometrical dimensions of the turbine. Using input conditions that included a turbine inlet temperature of $25^{\circ}C$, an outlet static pressure of 4.9 bar, and a mass flow rate of 1.16 kg/s, the results of a mean flow analysis show the major dimensions of the turbine, along with an angular velocity of 12,820 rpm. Based on these results, a three-dimensional turbine model is constructed for a computational fluid dynamics (CFD) analysis. The flow characteristics inside the turbine, including the volute and nozzle, are investigated using the CFD software ANSYS CFX. For a pertinent number of nozzle guide vanes, ranging from 10 to 15, the turbine efficiency was higher than 80%, with the highest efficiency shown by a nozzle with 15 guide vanes.