• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.114-120
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• 2005

This paper studies procedures for bottleneck detection in closed queueing networks(CQN's) with multiple job classes. Bottlenecks refer to servers operating at $100\%$ utilization. For CQN's, this can occur as the population sizes approach infinity. Bottleneck detection reduces to a non-linear complementary problem which in important special cases may be interpreted as a Kuhn-Tucker set. Efficient computational procedures are provided.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.141-144
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• 2021

최근 지상파 UHD 방송에서는 자막을 비디오 패킷에 삽입하여 전달하는 기존 방식이 아닌 별도의 전송로로 전달하는 폐쇄형 자막(closed caption) 방식을 적용하고 있다. 또한 자막에는 문자 뿐만 아니라 이미지까지 포함하여 청각장애인의 프로그램 이해도를 높이는데 활용할 수 있다. 따라서 본 논문에서는 청각장애 시청자가 방송 콘텐츠 내용의 이해도를 향상시키기 위하여 지상파 UHD 방송에서 기존의 문자 자막과 움직이는 이미지 자막(=감정표현 자막)을 송출하여 동시에 표현할 수 있는 송출시스템을 제안한다.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.152-159
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• 2003

This study was conducted to analyze the water consumption in closed transplants production system (CTPS) for the production of quality transplants and to investigate the effect of relative humidity on the water balance in CTPS. Potato (Solanum tuberosum L. cv. Dejima) plug seedlings were grown for 15 days at air temperature of 20$^{\circ}C$, relative humidity of 70%, photoperiod of 16/8 h, and photosynthetic photon flux (PPF) of 200 ${\mu}mol{\cdot}m^{-2}{\cdot}s^{-l}$ following rooting for 5 days in CTPS. Amount of humidified, dehumidified, irrigated and evapotranspirated water were 67.9 kg${\cdot}m^{-2},\;196.9{\cdot}m^{-2},\;44.3\;kg{\cdot}m^{-2},\;33.5\;kg{\cdot}m^{-2}$, respectively. Water content of media and plants were 1.2 kg${\cdot}m^{-2},\;6.9\;kg{\cdot}m^{-2}$, respectively. Three relative humidity levels of 60, 70, and 80% were provided to analyze the effect of humidity on the water balance in CTPS. Amount of humidified, dehumidified, irrigated, evapotranspiratad water and water contents of media and plants increased with increasing relative humidity. Since the water consumption required to produce plug seedlings in CTPS dec1eased with decreasing relative humidity, the available water utilization efficiency of CTPS increased with decreasing relative humidity. CTPS showed high available water utilization efficiency of 0.92 - 0.97 if dehumidified water in CTPS was recycled. The development of CTPS with recycling system of dehumidified water will not only reduce the water consuming for the production of transplants but contribute to the establishment of plant production economizing in water consumption.

• Journal of Bio-Environment Control
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• v.11 no.1
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• pp.40-44
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• 2002

A prototype of closed-type transplant production system(CTTPS) with fully environmental control was developed to produce massively quality transplants. Four photosynthetic photon flux(PPF) levels of 200,300,400 and 500$\mu$mol . m$^{-2}$ .s$^{-1}$ , four photoperiod levels of 1816 h,12/12h, 9/15 h and 6/18 h were provided to analyze the growth and development of cucumber plug seedlings(Cucumis sativus L., cv. Kyuewosalichungiang) as affected by PPF and photoperiod in a CTTPS. Effect of photoperiod on the growth and development of cucumber plug seedlings produced in a CTTPS was higher than PPF, Stem diameters dry weight of shoot and roots number of leaves, leaf with and length, and SPAD value of cucumber plug seedlings produced in a CTTPS were significantly high as compared to the control. But stem length of plug seedlings produced in a CTTPS was shorter than those of the control. Growth characteristics of cucumber plug seedlings raised at photoperiod of 6/18 h and PPF of 200$\mu$mol . m$^{-2}$ .s$^{-1}$ were similar to the those of the control. These results suggest that cucumber quality transplant can be produced at relatively short photoperiod and low PPF, It means that the electric energy consumed for the production of cucumber plug seedlings in a CTTPS can be saved.

• Review of KIISC
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• v.24 no.3
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• pp.54-66
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• 2014

SCADA 시스템은 독립적인 폐쇄된 환경에서 운영되는 산업 제어 시스템이다. 국가기간시설에 주로 이용되는 이 시스템에서 문제가 발생할 경우, 그 문제는 대재앙으로 확산될 수 있다. 최근에는 이 시스템들이 폐쇄된 환경에서 개방형으로 바뀌어가는 추세로 변화하고 있기 때문에, 정보망과는 다른 특징을 가진 제어 시스템에 대한 분석과 그에 대한 보안성 강화가 필요한 시점이 오고 있다. 본 논문에서는 현 시점의 국내외 정보망 및 제어 시스템에 대해서 어떠한 정보보호 관리체계가 적용되고 있는지 분석하고, 제어망의 특수한 성질에 근거하여 현 관리체계에 대한 한계점을 설명한다. 그리고 정보망과는 다른 제어 시스템만의 특징을 바탕으로 국내 제어 시스템에 대한 새로운 관리체계 방안에 대해서 부분적으로 제안한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.145-150
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• 2003

최근 육묘 시설의 양적 증가와 육묘 기술 수준의 향상에 힘입어 플러그 묘의 보급이 확대되고 있다. 더구나 육묘와 재배의 분업화가 진행되고, 고품질 묘의 안정된 수급에 대한 관심이 늘어나면서 육묘 산업에 대한 비중이 점차 증가하고 있다. 현재 국내에 설치되어 있는 온실, 터널 등의 모든 육묘 시설은 개방형 묘생산 시스템으로 자연광을 이용한 장점을 지니고 있으나, 여름철의 냉방과 겨울철의 난방에 소요되는 비용은 상당한 수준에 이르고 있다. 더구나 외부 기상조건과 밀접한 관계를 이루며 변화하는 특성을 가지고 있어 효율적인 환경제어를 위하여 차광과 보온 등의 시설이 필요하며(이 등, 1995), 관리노력이 적지 않게 요구되고 있다. (중략)

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.105-114
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• 2018

Modular system can be divided into two types based on the methods of resisting load. The one is the open-sided modular system composed of beams and columns. The other is the enclosed modular system composed of panels and studs. Of the Modular systems, the use of open-sided modular system is limited because it consists of closed member sections. In order to solve this problem, Choi et al.(2017) proposed a composite modular system with folded steel members filled with concrete. However, it was assumed in the previous study that the connections between modules are composed of rigid joint. Therefore it didn't identify the effect of connection behavior in structure. This study used finite element analysis to calculate stiffness of the connections in the proposed modular system. The linearization method presented in FEMA 440 is used for seismic performance assessment of structures, considering the connection stiffness computed in this study. The result of analysis shows that the capacity and story drift ratio obtained in the model considering stiffness of connection are less than those in the model not considering connection stiffness. Based on this observation, it is concluded that the stiffness of connection has a considerable effect on structural behavior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.9-18
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• 2019

Modular system can be divided into two types based on the methods of resisting load. The one is the open-sided modular system composed of beams and columns. The other is the enclosed modular system composed of panels and studs. Of the Modular systems, the use of open-sided modular system is limited because it consists of closed member sections. In order to solve this problem, Choi et al.(2017) proposed a composite modular system with folded steel members filled with concrete. However, it was assumed in the previous study that the connections between modules are composed of rigid joint. Therefore it didn't identify the effect of connection behavior in structure. This study used finite element analysis to calculate stiffness of the connections in the proposed modular system. The linearization method presented in FEMA 440 is used for seismic performance assessment of structures, considering the connection stiffness computed in this study. The result of analysis shows that the capacity and story drift ratio obtained in the model considering stiffness of connection are less than those in the model not considering connection stiffness. Based on this observation, it is concluded that the stiffness of connection has a considerable effect on structural behavior.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.569-572
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• 2006

디지털 기술의 획기적인 발전과 인터넷의 보편화로 인해 e-비즈니스가 차지하는 비중이 점점 더 커지고 있는 가운데 신속한 업무 결재가 중요시 되어 가고 있다. 이제는 결재 승인자가 외부에서도 웹 서버에 접속하여 결재자에게 전달되어진 결재문서를 검토, 결재 할 수 있도록 하는 시스템이 요구되고 있다. 그러나 기존의 업무 결재 시스템은 애플리케이션 형태로 회사 내에서만 사용할 수 있는 폐쇄형 시스템으로 업무의 효율성이 낮아졌다. 따라서 본 연구에서는 분산된 각 공정 중심의 업무 활동을 지원하는 웹 기반의 통합 전자결재 시스템 구상을 통해 효율적인 업무 결재가 될 수 있도록 시스템을 설계 및 분석 하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.120-130
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• 2020

This study examined the effects of perceived value (functional value, social value) and stress (complexity, insecurity) on continuous intention in SNS. In particular, this study examined the direct and indirect impacts of SNS type on the intention of continuing to use SNS. The research model was tested for 461 respondents that used SNS. SPSS 21.0 and PLS 2.0 techniques were used to perform reliability, feasibility, path and hierarchical regression analysis. The summary of the research results is as follows. First, the results indicate that functional value and social value have positive effects on satisfaction. Second, the results indicate that complexity had a negative effect on satisfaction. Third, the results indicate that insecurity and satisfaction have positive effects on continuous intention. Fourth, the results indicate that SNS type had a negative effect on continuous intention. Fifth, it was shown that SNS type had a moderating effect in the relationship between insecurity and continuous intention. Specifically, Insecurity had a stronger effect on continuous intention at closed-type SNS than open-type SNS. These findings suggest that closed-type SNS companies will have to address the anxiety of SNS users by providing various items and system devices.