• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.89-93
• /
• 2009

홍수기에 집중되는 하천유출량을 갈수기에 적절히 활용하기 위한 대표적인 시설이 댐이다. 제한된 용수공급량을 적절히 분배해 용수수요량을 만족시키면서 미래 갈수기시 용수공급을 위한 댐 저류량을 조절하는 것이 댐 운영의 중요한 목적 중 하나이다. 본 연구에서는 댐 저류량에 따라 댐 계획방류량을 일정비율 줄여주는 Hedging Rule을 5단계로 적용하여 댐의 상시만수위 저류량에 대한 실제 저류량의 편차 절대치 합, 수요에 대한 용수공급 부족량의 합, 그리고 하천유지유량에 대한 하천유량 부족량의 합을 목적함수로 하여 혼합정수 선형계획법(MILP, Mixed Integer Linear Programming)으로 식을 구성하였다. 한강수계의 다목적댐인 충주, 횡성, 소양강 댐과 용수전용댐인 광동 댐, 그리고 발전용 댐이지만 비교적 큰 저류용량을 가진 화천 댐을 댐 연계 운영 대상으로 하여 수자원장기종합계획의 2003년 유출량 및 수요량 자료와 댐운영실무편람의 댐 계획방류량 자료를 10일 단위로 입력하여 GAMS/CPLEX를 이용해 최적화하였다. 그 결과 생공용수 수요량 99.99%, 농업용수 수요량 99.91%, 그리고 하천유지용수 수요량 99.24%를 충족시키면서, 댐 저류율이 66.54%에서 86.39%로 증가하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.100.2-100.2
• /
• 2011

본 연구과제는 유망상품인 "발전용 MCFC 모듈형 BOP" 중 가습기 내부에 장착되는 연료-물 Mixing 시스템을 개발하는 것이다, 가습기 내부에서 공급된 연료-물은 연료전지 스택(Stack)으로부터 가습기로 유입된 고온의 가스로부터 열을 공급 받아 증발 및 혼합과정을 거치게 되며, 스팀-연료 혼합기로 형성되어 개질기(reformer)로 공급되게 된다. 이때, 물과 연료의 공급 상태에 따라 균일한 스팀-연료 혼합기가 형성되는지가 결정되며, 경우에 따라서는 고온의 가습기 내부의 국부적 온도분포의 큰 차이를 발생시켜 용접부의 균열을 발생시킬 수도 있기 때문에, 가습기의 설계와 함께 중요한 장치로 여겨진다. 본 연구에서는 다양한 가습기에 적용이 가능한 Mixer 모델을 설정하고, Analytic calculation을 통한 노즐설계와 1pass/Full scale 성능 실험 장치를 통해 상용화를 목표로 추진 되었으며, 특히 노즐별 유량분배 변동율은 ${\pm}3%$ 이내로 달성하고, 스팀/연료 공급 비율은 2:1 이내로 달성할 수 있는 시스템을 구축하게 될 것이다. 최종적으로 개발 완료 시 다양한 가습기에 직접 장착하여 운전이 가능할 수 있도록 실용화에 중점을 두고, 보다 안정적인 성능을 나타낼 수 있는 제품 개발이 가능하리라 사려된다.

• The KIPS Transactions:PartA
• /
• v.10A no.5
• /
• pp.487-492
• /
• 2003

To satisfy the requirements for QoS of Users using multimedia content stream service, it is required to control mechanism for QoS based on class priority, URFA classifies the user by two classes (super class, base class) and controls the admission ratio of user's requests by user's class information. URFA increases the admission ratio class and utilization ratio of stream server resources.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.4
• /
• pp.698-705
• /
• 2016

In this study, we have studied the polymerization of polyethylene wax using metallocene catalysts and its physical properties. Various polymerization conditions were tried for polymerization of polyethylene wax. We have evaluated hydrogen reactivity and studied on characteristics of polymerization effected by ligand structure of metallocene catalysts against Ziegler-Natta catalysts which are widely used for polymerization of polyethylene. We have also checked hydrogen used for chain transfer agent, molecular weight change and distribution by different ratios of ethylene gas. Finally, we suggest proper structure of metallocene catalysts for polymerization of polyethylene wax.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.5
• /
• pp.939-948
• /
• 1997

In this paper, we propose the new rate-based transmission rates control algorithm that allocates the fair band-width for ABR service in ATM network. In the traditional ABR service, bandwidth is allocated with constant rate increment or decrement, but in the proposed algorithm, it is allocated fairly to the connected calls by the fuzzy inference of the available bandwidth. The fuzzy inference uses buffer state and the buffer variant rate as the input variables, and uses the total transmission rate as a output variable. This inference a bandwidth is fairly distributed over all ABR calls in service. By simmulation, we showed that the proposed method improved 0.17% in link effectiveness when RIF, RDF is 1/4, 38.6% when RIF, RDF 1/16, and 82.4% when RIF, RDF 1/32 than that of the traditional EFPCA.

• Land and Housing Review
• /
• v.12 no.2
• /
• pp.79-89
• /
• 2021

This simulation based study analyzed the horizontal daylight distribution on the floor and ceiling of a small office space based on window orientations and interior window blind positions. South and north facing windows were each tested without window blinds and with window blinds at 45° and 180° (horizontal). The study showed that the illuminance value was highest 1m from the window. On the floor and ceiling, the difference in illuminance value was the greatest and least in December and June, respectively. The indoor illuminance value was highest when there was no window blind and under south-facing conditions. The greatest illuminance difference occurred between window blinds positioned at 45° and 180°. Under north-facing conditions, windows without blinds or with blinds at 45° had the least impact on indoor illuminance with illuminance being more evenly distributed.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.16 no.3
• /
• pp.219-226
• /
• 2014

Evaluation of tree responses to temperature elevation is critical for a development of forest management techniques coping with climate change. We conducted a study on the growth responses of Betula costata, Fraxinus rhynchophylla, and Quercus variabilis seedlings to open-field artificial warming. Artificial warming set-up using infra-red heater was built in 2012 and the temperature in warmed plots was regulated to be consistently $3^{\circ}C$ higher than that of control plots. The seeds of three species were sown, and the responses of growth, biomass allocation, and net photosynthetic rate of newly-germinated seedlings on the open-field artificial warming were determined. As a result, the growth responses of the seedlings differed with the species. B. costata showed decreases in the height to diameter ratio (H/D ratio), biomass, root weight to shoot weight ratio, and net photosynthetic rate. However, root collar diameter (RCD), height, biomass, and net photosynthetic rate of Q. variabilis were increased, while the response of F. rhynchophylla was rather obscure. There was no significant difference between warmed and control plots in seedling growth for 3 species in July, whereas, RCD, height, and H/D ratio of Q. variabilis were increased and H/D ratio of B. costata was decreased in November under warming. Species-specific growth responses to warming were similar to the species-specific responses of net photosynthetic rate and biomass allocation; therefore, net photosynthetic rate and biomass allocation might attribute to growth responses to warming. Besides, a relatively obvious response in autumn compared to summer might be affected by the phenological change following artificial warming. Species-specific responses of three deciduous species to warming in this study could be applied to the development of adaptive forest management policies to climate change.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.48 no.2
• /
• pp.45-55
• /
• 2020

In terms of environmental justice, urban parks play a pivotal role in imperative amenities allowing for physical activity. The reasonable distribution of urban park services must be considered in terms of community demand and the context of the park. The purpose of this study is to analyze the inequity of qualitative park service according to the socioeconomic status(SES) in Daegu. The qualitative service was assessed for 82 neighborhood and walking-distance parks by utilizing the NGST(Neighborhood Green Space Tool). The inequity was analyzed by SES variables(ratio of basic living recipients, ratio of single-parent families, average housing sales, dilapidated dwelling ratio, and park area per capita). The features of the qualitative equity in Daegu is as follows. First, urban park planning in Daegu is in parallel with the development of residential areas rather than the local policy. The development pattern of parks stretching from center of the city to outskirts clearly dissociates the city based on socioeconomic status. The parks in the center are relatively old and poorly managed. Second, overall neighborhood parks lacked recreational facilities. The facilities are significantly influenced by the housing values around them. The lower the recreation facility score, the higher the floor gradient of the urban parks constraining physical activities. Third, the quantitative supply of parks has nothing to do with the quality of the urban parks. Green space distribution is highly dependent on natural park areas, so the park area per capita cannot be a standard for assessing qualitative equity.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.110-124
• /
• 2011

Even though Korea has long experienced single race/ethnic demographic composition, the recent rapid change of demographic diversity will have powerful impact on the HRM(human resource management) in the future. In this research we find the influence of the diversity friendly HRM to the human resource practices using the data of WPS(Workplace Panel Survey) of Korea Labor Institute. If the training for women is high, the density of the woman increased. The performance pay is introduced, then the density of the disabled person would be increased. The foreign workforce was also increased if the company used more selection methods. But the HRM practices such as talent management, yearly-based compensation systems, and appraisal program which has a tendency to reduce diversity have no significant influence to the financial performance. This findings imply that the management team should introduce the effective HRM systems to manage diverse human resources after considering the organizational culture and business environment. This research intends to find the diversity friendly HRM practices and hope to help the efforts of the management team to find effective management methods.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.162-162
• /
• 2017

AlCrN 코팅은 높은 경도, 낮은 표면 조도 등의 상온에서의 우수한 기계적 특성 이외에 고온에서 안정한 합금상의 형성으로 인하여 우수한 내열성을 보이는 코팅이며, Si을 첨가하여 나노복합구조를 갖는 AlCrSiN 코팅은 고경도 특성을 나타내는 나노결정립과 고내열성을 나타내는 $Si_3N_4$ 비정질이 동시에 존재함으로써 뛰어난 고온 특성까지 보유하여 공구 코팅으로의 적용 가능성이 크다. 본 연구에서는, 가혹화된 공구사용 환경 대응 하는 더욱 우수한 내마모성 및 내열성을 보이는 코팅막을 개발하기 위해 AlCrN/AlCrSiN 이중층 코팅을 합성하였다. 합성된 코팅의 구조 및 물성을 분석하기 위해 field emission scanning electron microscopy(FE-SEM), nano-indentation, atomic force microscopy(AFM) 및 ball-on-disk wear tester를 사용하였다. 내열성을 확인하기 위하여 코팅을 furnace에 넣어 500, 600, 700, 800, 900도에서 30분 동안 annealing한 후에 nano-indentation을 사용하여 경도를 측정을 하였다. 5:5, 7:3, 9:1의 두께 비율로 AlCrN/AlCrSiN 이중층 코팅을 합성하였으며 모든 코팅의 두께는 $3{\mu}m$로 제어되었다. AlCrN 코팅층의 두께가 증가할수록, 이중층 코팅의 경도 및 내마모성은 점차 향상되었지만 코팅의 밀착력은 감소하였다. 일반적으로 AlCrN 코팅은 상대적으로 높은 잔류응력을 갖고 있으므로, AlCrN 층의 두께비율이 증가함에 따라 코팅내의 잔류응력이 높아져 코팅의 경도는 증가하고 밀착특성은 낮아진 것으로 판단된다. AlCrSiN 상부층 공정시 기판 바이어스 전압을 -50 ~ -200V 로 증가시키면서 이중층 코팅을 합성하였다. XRD 분석 결과, 공정 바이어스 전압이 증가함에 따라 AlCrSiN 상부층은 점차 비정질화 되었고, 코팅의 경도와 표면 특성이 향상되는 것을 확인하였다. 이러한 특성 향상은 높은 바이어스 인가가 이온 충돌효과의 증가를 야기시켰으, 이로 인해 치밀한 코팅층 합성에 의한 결과로 판단된다. AlCrN/AlCrSiN 이중층 코팅을 어닐링 한 후 경도 분석 결과, -150, -200V에서 합성한 코팅은 900도 이상에서 26GPa 이상의 높은 경도를 보인 것으로 보아 우수한 내열성을 갖는 것으로 확인 되었다. 이는 AlCrSiN 상부층의 높은 Si 함량 (11at.%) 으로 인한 충분한 $Si_3N_4$ 비정질상의 형성과, 고바이어스 인가로 인한 AlCrN 결정상과 $Si_3N_4$ 비정질상의 고른 분배가 코팅의 내열성을 향상시키는데 기여를 한 결과로 판단된다.