http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Yusik Kim,Yongjun Choi,Jihyeok Choi,Sangho Lee 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.5
Membrane distillation (MD), which uses hydrophobic porous membranes with a temperature gradient to produce pure water, has the potential to treat high-salinity wastewater. However, it cannot directly treat wastewater containing surfactants, which lower the surface tension and thus result in membrane wetting. To overcome this limitation, this study proposed a hybrid process consisting of powdered activated carbon (PAC) adsorption and MD, where PAC removes the surfactants in the wastewater to alleviate the wetting of the MD membranes. A bench-scale vacuum-assisted air gap MD (V-AGMD) equipment was adopted for the treatment of synthetic wastewater containing inorganic salts and surfactants. The conductivity of the permeate from V-AGMD was continuously monitored to detect membrane wetting. Without the use of PAC, the MD membrane was wetted within a short period, which decreased as the surfactant concentration increased. On the other hand, the addition of PAC retards the onset of wetting even at higher surfactant concentrations. The effectiveness of the PAC addition to the MD system on wetting control was examined under various conditions to elucidate its mechanism.
모바일 스튜디오: 클라우드로의 효율적인 오프로딩 기법 연구
김유식 ( Yusik Kim ),박용성 ( Yong-sung Park ),윤찬현 ( Chan-hyun Youn ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.1
모바일 클라우드 컴퓨팅 기술이 대두 됨에 따라, 모바일 단말기의 이동성과 클라우드의 컴퓨팅 파워 및 스토리지 자원의 장점을 모두 취합하는 어플리케이션 개발이 가능해졌다. 모바일 어플리 케이션 사용자에게 클라우드의 존재가 마치 보이지 않는 것처럼 끊김 없이 작은 오버헤드로 전송을 하는 아키텍처를 제안하고자 한다.
진공 보조 공기 간극형 막증류법 성능에 대한 막 변형의 영향
김유식 ( Yusik Kim ),최용준 ( Yongjun Choi ),조형락 ( Hyeongrak Cho ),이상호 ( Sangho Lee ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-
Membrane distillation (MD) is a promising technology for seawater desalination, wastewater reclamation, and zero liquid discharge due to its many advantages. Among various process configurations, air gap membrane distillation (AGMD) has been widely adopted for practical applications. Nevertheless, there are inherent limitations in AGMD, leading to low flux and productivity. Recently, a few studies have attempted a vacuum assisted AGMD (V-AGMD) to overcome this drawback. Nevertheless, little information is available on factors affecting the performance of V-AGMD. Accordingly, our work focused on the effect of applied vacuum on the membrane in V-AGMD. Experiments were carried out in a laboratory-scale V-AGMD set-up. Commercial flat sheet membranes were used for these experiments. A mathematical model was developed and applied to analyze the experimental results. After the experiments, the membranes were taken out from the module and examined using scanning electron microscopy (SEM), contact angle (CA), and liquid entry pressures (LEPs) measurements. Results showed that the MD flux increased with increasing the degree of the applied vacuum. However, the measured flux was higher than the calculated flux from the theoretical model. The visual examination of the membranes after the experiments confirmed that the membranes were deformed by the vacuum even. The degree of the membrane deformation was significant when spacers were not used to support the membrane. The deformation became more serious with an increase in the depth of the air gap. The SEM results revealed that the pore size of the membrane increased with the membrane deformation. The effect of the membrane deformation on CA, LEP, and salt rejection was also investigated. These results strongly suggest that the control of the membrane deformation is critical for design and operation of V-AGMD systems.
김유식 ( Yusik Kim ),윤찬현 ( Chan-hyun Youn ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.1
사용자 지향형 클라우드 협업 시스템이 가지는 장점은 다양한 클라우드 서비스 제공자들로부터 컴퓨팅 자원을 제공받기 때문에, 넓은 폭에서 선택이 가능한 점이다. 이것이 가능하려면, 다양한 컴퓨팅 자원들의 기대 성능값을 사전에 알아서 사용자가 사용하는 애플리케이션의 특성을 고려하여 자원들을 평가하고 가장 높은 성능 기댓값을 가지는 자원을 찾을 수 있어야 한다.
김유식 ( Yusik Kim ),윤찬현 ( Chan-hyun Youn ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.2
하나의 클라우드 서비스 제공자가 제공하는 컴퓨팅 자원의 양과 종류에는 한계가 있다. 이를 극복하려면 클라우드 협업 기술인, 다중 클라우드 자원 브로커를 활용하여, 이종 자원을 탐색하여 사용자에게 제공하는 기술이 필요하다. 본 논문에서는 다중 클라우드 자원 브로커 시스템의 구조를 제안하고, 이종 자원 탐색에 필요한 성능 지표와 LP 모델을 이용한 최적화 기법을 제안하고자 한다.
클라우드 환경에서 VM 간섭 제어를 고려한 비용 효율적인 VM 배치
김희재 ( Heejae Kim ),김유식 ( Yusik Kim ),윤찬현 ( Chan-hyun Youn ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.2
가상화 기술의 발달은 클라우드 데이터센터(cloud datacenter)에서의 서버 통합(server consolidation)을 지원하며 이를 통하여 물리적 머신(physical machine, PM) 관리 비용을 감소시킬 수 있다. 그러나 서버가 통합됨에 따라 가상 머신(virtual machine, VM) 간섭이 생길 수 있고 이는 성능 감소의 원인이 된다. 따라서 VM 간섭과 PM 관리 비용을 감소시키는 것은 트레이드오프(trade-off)를 이루며 본 논문에서는 이를 해결하기 위하여 VM 간섭 계측(quantizing)을 위한 기법과 비용 효율적 VM 배치(placement)를 위한 휴리스틱(heuristics)을 제안한다.
서울대학교 내 초절수변기 교체에 따른 절수효과 및 편익분석
한무영 ( Mooyoung Han ),남궁은 ( Eun Namkung ),원유식 ( Yusik Won ),박현주 ( Hyunju Park ),김미경 ( Mikyeong Kim ),김용인 ( Youngin Kim ),김상래 ( Sangrae Kim ) 한국수처리학회 2017 한국수처리학회지 Vol.25 No.1
The objective of this study is to suggest effective ways to solve water shortage problems by water saving achieved from a toilet retrofitting program at Seoul National University. 35 bowls in building #35 were changed from conventional bowls to high efficiency bowls. Water saving effects were analyzed after 8 months of water saving and benefits data collection. The flow amount was decreased from 238.73 to 94.38 for a month. Assuming that all 8,176 bowls are changed in Seoul National University, amount of 378,237 water can be saved and initial investment will be returned in years. Moreover, due to conserve electricity 239 ton of carbon dioxide are expected to reduce. To maximize benefits, social system improvements such as providing incentives from suppliers is necessary
Fixed-Complexity LLL-Based Signal Detection for MIMO Systems
Yusik Yang,Jaekwon Kim IEEE 2013 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.62 No.3
<P>Recently, a hardware-friendly fixed-complexity Lenstra-Lenstra-Lovász (fcLLL) algorithm has been developed for use in the linear receivers of multiple-input-multiple-output (MIMO) systems. In this paper, we propose a novel fcLLL-based detection method that significantly outperforms conventional fcLLL-based linear receivers at a lower fixed complexity. The main idea is that the complexity of fcLLL can be significantly reduced by disregarding a single column of the channel matrix. We also propose column selection methods that consider both the error performance and complexity simultaneously. Simulations are performed to demonstrate the efficacy of the proposed method.</P>