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충격파 터널용 마하 6 컨투어 노즐의 출구 압력 측정 및 해석
박상하(Sangha Park),김근영(Keunyeong Kim),장병국(Byungkook Jang),박기수(Gisu Park) 한국추진공학회 2019 한국추진공학회 학술대회논문집 Vol.2019 No.11
풍동 장비에서의 유동 균질성 연구는 풍동에서 측정하는 모델에서의 측정 정확도를 향상시키기 위해 중요하다. 본 연구에서는 충격파 터널에 사용되기 위해 설계 및 제작된 마하 6 컨투어 형 노즐의 출구압력 측정을 수행하고 이를 바탕으로 본 노즐 유동의 시뮬레이션 검증을 수행하였다. 본 연구의 결과는 타 지상실험 풍동 장비의 노즐 설계 및 다양한 발사체 노즐에 참고 가능할 것이다. Flow uniformity research in windtunnel equipment is important to increase measurement accuracy of properties on model surface. In this study, nozzle exit pressure was measured in contour nozzle that designed for shock tunnel, and simulation of nozzle flow based on nozzle pressure data has been done. The result of this study will be referenced for design various types of nozzle used ground windtunnel facility and nozzle for launch vehicle.
효과분석을 이용한 하이브리드차량 구동계용량 최적조합에 대한 연구
박상하(Sangha Park),이재훈(Jaehoon Lee),허승진(Seung-Jin Heo) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
In this study, We propose the optimal combination of HEV powertrain component size. a design range of HEV powertrain component size is presented base on Vehicle longitudinal dynamics. we create 8 experiments by using design of experiments(DOE). And then, we simulate a fuel consumption, state of charge(SOC) and acceleration performance by using Green Car Virtual Integrated Development Environment (G-VIDE). We conduct Effects analysis by using Design of Experiments for HEV powertrain component size optimal combination. The optimal combination meet target longitudinal performance with low fuel consumption.
IEEE 802.11 무선LAN에서 AP의 백오프가 TCP성능에 미치는 영향에 관한 연구
박상하(Sangha Park),우희경(Heekyoung Woo),김종권(Chongkwon Kim) 한국정보과학회 2005 한국정보과학회 학술발표논문집 Vol.32 No.2
IEEE 802.11 에서 현재까지 많이 연구되어진 주제는 노드들 간의 공평성(fairness)에 중점을 두거나 처리율(throughput)을 높이는데 초점을 맞추어 진 것들이었다. 전체 처리율을 높이는데 AP의 백오프 방식에 관련해서는 노드들 간에 관한 연구에 비하여 비교적 연구가 적은편이다. 현재 AP와 노드들은 충돌이 발생하면 BEB(Binary Exponential backoff) 방식으로 셋팅되어 사용하고 있기 때문에 1:N의 불공평한(unfairness) 상황이 발생한다. 하향링크(downlink)가 대부분인 환경에서 AP가 다른 노드들과 같은 채널 접근확률을 가진다는 것은 바람직하지 않다. 따라서 AP가 노드들보다 우선권(priority)을 높여서 처리율을 높이는 방안이 필요하다. 그래서 본 논문에서는 AP의 백오프 방식 및 CW(Contention Window)가 변화하는데 따라서 전체 처리율에 어떤 영향을 끼치는가와 노드 수에 따른 AP의 적절한 전략 과 백오프 CW값을 분석해 보았다.
Surrogate를 이용한 계층적 구조의 u-LifeCare 시스템 설계
박상하(SangHa Park),조진성(JinSung Cho) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.1D
유비쿼터스 컴퓨팅 시대의 도래와 삶의 질 향상을 위한 개개인의 건강 유지와 증진에 대한 욕구는 유비쿼터스 라이프캐어(u-LifeCare) 산업의 발전을 촉진시키고 있다. 본 논문에서는 기존 헬스캐어(HealthCare)시스템에 관련된 연구들의 문제점을 분석하고 이를 해결하기위한 새로운 u-LifeCare 서비스 시스템의 구조를 제안한다. 기존 헬스캐어 시스템의 구조는 대부분 중앙집중형 Client/Server의 구조를 가진다. 이런 구조는 서비스 제공을 위한 모든 처리와 Data가 중앙 서버에 집중되므로 서버의 오버헤드 현상을 발생시킬 수 있으며 이는 사용자에 대한 서비스 응답시간 (Response time)을 증대시키고 심할 경우 서버다운 현상을 초래 할 수 있다. 제안하는 구조에서는 Surrogate를 동적으로 발견하고 Computing resource로 이용함으로써 이러한 문제점들을 해결하고 효율적인 서비스를 제공할 수 있다.
Assessment Criteria for the Effective Implementation of VR in Modern Art Exhibitions
박상하 ( Sangha Park ),이현경 ( Hyun-kyung Lee ) 한국디자인트렌드학회 2021 한국디자인포럼 Vol.26 No.1
Background Virtual reality (VR) technology is being increasingly employed in art exhibitions worldwide. There are various reasons for such implementations, of which the most prominent is that VR technology serves to attract visitors by offering novel experiences. The article aims to answer the following esearch question: how can VR technology be employed in exhibitions as an effective communication medium? The efficacy of such technology, however, differs according to its specific traits. The paper seeks to determine how one can discern between effective and ineffective VR implementations. Methods To find assessment criteria for effective VR implementation, the paper analyzes previous literature. Moreover, the paper aims to find model cases per criterion for illustration. Results This paper proposes the use of three criteria for such differentiation: interaction, immersion, and presence. Moreover, it discusses three actual exhibitions that are representative cases for each criterion. For interaction, “We Live in an Ocean of Air” is the model case, “Lee Jung Sub VR” is a well-implemented exhibition that excels at immersion, and “Björk VR” illustrates presence. Conclusion The three criteria and model cases offer valuable guidelines for assessing VR implementation in exhibitions, aiding future exhibition coordinators to use VR technology for effectively enabling interactive experiences for visitors.
박상하 ( Sangha Park ),김욱 ( Wook Kim ),김명선 ( Myeongsun Kim ),김연정 ( Yeonjeong Kim ),정석희 ( Sokhee P. Jung ) 한국폐기물자원순환학회 2021 한국폐기물자원순환학회지 Vol.38 No.3
Solar energy is attracting attention as a major source of renewable energy. Solar power generation has grown rapidly since the 2000s. Owing to the recent indications of a rapid increase in solar power generation wastes, it is imperative that countermeasures be implemented. Accordingly, the Korean government introduced an extended producer responsibility (EPR) system to resolve the problem of solar panel disposal and recycling; however, there are some requirements that do not reflect the domestic conditions. This paper discusses the EPR system expected to be introduced in the future and the directions of improvement of domestic laws in the treatment of solar panel wastes. First, necessary measures must be considered to prevent leakage of lead and harmful substances in landfills during waste panel treatment. Currently, most of the solar panels that are not exported are being disposed through landfills. Lead and arsenic were detected in these wastes by dissolution analysis of the solar panel samples manufactured in Korea, which shows their capacity for environmental damage. Therefore, it is necessary to improve the existing treatment methods and to prepare countermeasures against illegal disposal of solar panel wastes. Second, it is necessary to take action against enterprises responsible for demolition, transportation, and disposal of such wastes. Solar power generation facilities are generally installed by legally specified contractors, but in the case of dismantling and transporting waste panels, there are no legal designations for relevant personnel. Third, it is necessary to establish a recycling system for these wastes. Domestic solar panels are generally exported overseas, but there is uncertainty about export to overseas markets, so the domestic recycling market should be revitalized. In Korea, a recycling system is not established, and no technology is available for recycling. Therefore, research on recycling technologies and establishment of a rational system are necessary. Finally, it is necessary to extend the lifespan, improve efficiency, and increase the possibility of reusing solar panels by improving their technology. Currently, the installed photovoltaic power generation facilities are vulnerable to recycling and reuse and have short lifespans. Therefore, it is necessary to increase the lifespans of solar panels through technological developments, efficiency improvements, and focus on future reuse of the panels.
박상하(Sangha Park),박기수(Gisu Park) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.11
본 연구에서는 표면 거칠기가 선두부의 열 · 공력 환경에 미치는 영향을 실험적으로 검토하였다. 실험은 마하 6 유동의 충격파 터널 설비를 이용해 수행됐다. 본 실험을 통해 측정된 결과 중 정체점에서의 선두부 모델 표면 압력 및 열전달량은 등엔트로피를 가정한 이론 계산을 통한 비교를 통해 검증하였다. 실험 데이터를 고려하였을 때, 매끄러운 벽면과의 거친 벽면 케이스에 대해 표면 압력의 경우 큰 변화를 보이지 않았으나, 열전달량에서 현저한 차이가 나타났다. In this study, the influence of surface roughness on the forebody aerothermodynamics has been examined experimentally. The experiment was conducted using a shock tunnel facility at a freestream nominal Mach number of 6. The measured surface pressure and heatflux at the stagnation point were compared with that of theoretical analysis based on the isentropic assumption. Considering the experimental data, a small difference is seen in the surface pressure, however a noticeable difference in the variation of surface heatflux was found for the rough wall case than that of the smooth wall.
그린카 가상개발환경을 위한 구동계모델 성능향상에 대한 연구
박상하(Sangha Park),김진성(Jinsung Kim),이재훈(Jaehoon Lee),허승진(Seung-Jin Heo) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
In this paper, a virtual simulation model to analyze performance of hybrid electric vehicle is presented. Simulation model consist of dynamic models of HEV powertrain. In order to estimate the performance of HEV: Power Split type HEV, a HEV simulator is developed using MATLAB/SIMULINK. Using driving mode simulation (UDDS: Urban Dynamometer Driving Schedule) performance of HEV were calculated. In order to consider each model of accuracy, the simulation has compared with Autonomie.