• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.159-159
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• 2015

상수관망시스템의 신뢰도를 정량화하기 위한 연구가 최근 활발히 진행되고 있다. 대부분의 연구는 절점의 공급가능수요량, 절점의 수두, 그리고 유량과 수두를 동시에 고려한 에너지(energy)를 이용하여 신뢰도 지수를 개발하였다. 이 중, Energy를 기반으로 하는 신뢰도지수로써 Resilience index(Todini, 2000), Network Resilience index(Prasad, 2004), Modified Resilience index(Jayaram, 2008)와 Entropy Resilience index(Raad, 2010) 등의 연구가 대표적이다. 상수관망시스템에 정상적인 상황을 넘어서는 부담이 가해졌을 때, 이를 완충하거나, 정상적인 용수공급 상황으로 빠르게 회복하는 능력인 복원력(Resilience)을 판단하기 위한 지표로써 제시된 Todini의 Resilience index를 기점으로, 상수관망의 신뢰도(Reliability)을 Energy 측면에서 판단할 수 있는 관련 지표에 대한 연구가 진행되어왔다. 특히, 상수관망의 최적설계 시, 상수관망의 기능적 요소로써 관련 지표들을 비용(Cost)과 함께 다중목적함수로 고려하는 연구까지 다수 진행되고 있으나, 이러한 지표들이 상수관망에서 핵심적인 몇 가지 요소들의 변화에 대하여 어떻게 반응하는지에 대한 분석은 제대로 이루어지지 않고 있다. 본 연구에서는 동일한 상수관망시스템에서 용수의 흐름상황을 크게 좌우할 수 있을 것으로 판단되는 몇 가지 변동상황을 고려하여 이러한 지표들이 각각의 변동상황에 어느정도 민감하게 반영하는지 분석하였다. 여기서, 상수관망시스템의 중요 변화요소로써 1) 수요량의 변화, 2) Loop 개수의 변화, 3) 수원지(Source) 개수의 변화, 4) 해당시스템의 최소 요구수압 변화 등을 고려하였다. 본 연구를 통해, 상수관망시스템의 신뢰도 산정에 활용되고 있는 기존의 지수들이 다양한 변동 상황을 얼마나 잘 반영할 수 있는지를 파악하고, 기존의 지수들을 보완한 개선된 신뢰도 지수의 개발가능성을 모색하도록 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.4
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• pp.661-668
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• 2023

A large amount of fuel is required for heating the agricultural facility house, and many farmhouses are experiencing the burden of heating costs due to the recent increase in fuel prices. This paper proposes a supply system that supports heating of agricultural facility houses located nearby by utilizing industrial chimney waste heat, and analyzes the application and effect of a heating cost reduction model. The system was designed based on the chimney waste heat system, and the facility house heating cost reduction model was applied and effect analysis was performed based on the proposed model. It was confirmed that the high-temperature waste heat from the chimney can be used to supply heating to facility houses in nearby farms. If heating is supplied to large-scale facility houses near industrial complexes, it is expected to contribute to improve productivity and competitiveness of domestic farms.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.46-46
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• 2021

국제사회는 1992년 기후변화협약 체결 이후 지구온도 상승을 2℃이하로 억제하는 등 기후변화 문제를 해결하기 위해 노력하고 있다. 그러나 1997년 선진국(38개국) 중심으로 2020년까지 탄소감축(교토의정서)을 선언하였음에도 불구하고, 미국, 중국 등의 감축의무 미참여로 인해 기후변화대응에 대한 한계를 노출한 바 있다. 그 이후 COP21(2015년)에서 모든 국가에 감축의무를 부여하는 신(新)기후체제를 출범함으로써 선진국뿐만 아니라 개발도상국도 2020년부터 탄소감축의무를 부담하게 되었다. 영국은 기후변화위원회의 권고에 따라 탄소중립경제(Net-Zero Economy) 실현을 위해 국가적 탄소배출 목표를 발표(2019년)하고 온실가스 배출 'Zero'를 기후변화법에 명시하여 모든 산업 인프라 및 환경에 적용시키려 한다. 전 세계에서 최초로 영국의 물산업 분야는 'Net Zero 2030 Routemap'을 발표하여 물산업분야의 탄소중립 실현을 위해 다양한 정책적 로드맵과 실행방안(시나리오)을 수립하였다. 이러한 실행방안은 국가정책에 부합하고 자국내 물기업의 탄소저감 실행계획의 수립을 지원하는데 그 목적이 있다. 구체적인 실행방안은 탄소중립 달성을 위해 비용, 효과, 기술수준 및 기간 등을 고려하여, ①수요주도형, ②기술주도형, ③자연친화주도형, 그리고 ④복합형으로 제시하고 있다. 실행시나리오에 따르면, 수요주도형은 상하수도 분야 수요관리 및 기술, 설비의 효율화를 통한 배출 저감 방안으로 2018~19년 기준, 총배출량 2.41MtCO2e에서 2030년까지 0.54MtCO2e으로 약 77%의 감소효과를 기대하고 있다. 기술주도형의 경우, 심각한 탄소배출 분야의 기술개발 및 혁신을 통해 배출량을 최소화하는 시나리오이며, 총배출량(2.41MtCO2e)을 0.10MtCO2e(약 96%)까지 감소시키기 위한 방안이다. 자연친화주도형은 물기업의 자산 및 그 외 지역에 자연친화적 환경조성을 통한 탄소상쇄방안을 중심으로 총배출량을 0.88MtCO2e(약 63%)까지 저감하는 효과를 나타낸다. 마지막으로 복합협은 시나리오별 실효성과 적용시기를 고려할 때 가장 효과적인 방안으로 약 74%의 저감효과를 나타내지만, 시기적절성, 효과성에서, 가장 최적의 방안으로 제시되고 있다. 본 연구는 이러한 영국 물산업 분야의 탄소중립 정책과 실행방안 분석하고 그 시사점을 제시함으로써 국내 물산업 분야의 탄소중립을 위한 구체적 실행계획 수립에 이바지하고자 한다. 물산업 분야의 탄소중립은 기존 물산업 가치사슬 변화 등 물산업 생태계 전반의 변화를 초래할 것이며, 이러한 변화는 국내 물산업의 자본·운영시장의 비용증가에 대한 도전과 신재생에너지 기술 등 탄소 중립 기술 습득 및 새로운 일자리 창출 등 신(新)시장체계에 대한 기회가 동시에 상존한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.33-42
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• 2013

In the early stage of P2P, the technology was limited to narrow usage of file sharing, but currently, P2P technology has become essential to maximize the efficiency between associated technologies without additional deployment of high costly infrastructure and also the burden of the server. Especially, P2P media streaming service is a highly attractive service to mobile users. which requires a higher quality in the mobile environment in accordance with the development of technology of wired network as well as better mobile terminals. However, P2P technology should consider the trade-off between 'peer selfishness' and QoE for providing fairness. The P2P system also try to maximize the resource utilization through an incentive mechanism for service differentiation and encourage peers to contribute continuously for improving the overall system performance. In this paper, we propose an point-based incentive mechanism based on peer's contribution level and energy availability for service differentiation. We also introduce that the proposed mechanism efficiently enhances the system performance as the peer with incentive using contribution and energy obtains more effective resource distribution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.71-78
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• 2014

There is a big risk of bullet impact because military rotorcraft is run in the battle environment. Due to the bullet impact, the rapid increase of the internal pressure can cause the internal explosion or fire of fuel cell. It can be a deadly damage on the survivability of crews. Then, fuel cell of military rotorcraft should be designed taking into account the extreme situation. As the design factor of fuel cell, the internal fluid pressure, structural stress and bullet kinetic energy can be considered. The verification test by real object is the best way to obtain these design data. But, it is a big burden due to huge cost and long-term preparation efforts and the failure of verification test can result in serious delay of a entire development plan. Thus, at the early design stage, the various numerical simulations test is needed to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact numerical simulation based on SPH(smoothed particle hydrodynamic) is conducted with the commercial package, LS-DYNA. Then, the resulting equivalent stress, internal pressure and bullet's kinetic energy are evaluated in detail to examine the possibility to obtain the configuration design data of the fuel cell.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.39-48
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• 2014

The speed of aging society is increasingly getting faster in Korea. Currently, there are over one million elderly living alone, which represents more than 19% of the total elderly in Korea. Although various policies and research have been implemented for caring the elderly living alone, there have been obvious limitations in realization of the caring system due to inconvenience, privacy violation, difficult operation and maintenance. Therefore, the objective of this study is to develop a method and a prototype system to monitor safety of elderly living alone by using energy usage information of automatic meter reading device. The proposed system is expected to improve or resolve the existing limitations and to provide 24 hour monitoring and early detection of death for the elderly living alone without adding staffs for operation and maintenance in a more effective and economic way.

• Journal of Wetlands Research
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• v.23 no.3
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• pp.252-259
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• 2021

Numerous valley waters originating from Mt. Mudeung and flowing into Gwangju Cheon flowed into the confluence-type sewage conduit, the Gwangju Cheon became dry and water quality deteriorated. In this study, a method to create a stream was studied by using the valley water of Mt. Mudeung in the Gwangju cheon that flows into the sewage treatment plant as a water source. Flow and water quality surveys were investigated at four points with meaningful flow quantity. As a result, it showed a flow quantity was 105~2,721 m³/day at each point. And the average water quality was BOD₅ 0.3~1.6 mg/L. If a stream with a flow quantity of 1,500 m³/day is created during the dry season and then flows into the Namgwang bridge of Gwangju cheon, it is predicted that there will be improvements in BOD 7.3%, COD 6.5%, T-P 5.8%, and T-N 5.2%. In addition, it was determined that the load on the flow quantity of the sewage treatment plant due to the inflow of valley water would be reduced, the cost of sewage treatment would be reduced, and it would be the basis for BGN construction by creating waterside amenity in the city.

• Journal of The Korean Society of Grassland and Forage Science
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• v.28 no.2
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• pp.99-106
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• 2008

This experiment was carried out to show a reform measures by grouping for problems by the survey of TMR plants. Twenty total mixed ration (TMR) plants (10 cooperation and 10 private plants) were surveyed, of which 13 plants, 65% of total TMR plants, committed TMR formulae to a outside nutrition specialist (TMR formulator). With respect to consulting fee for TMR formulae, $500{\sim}900$ thousands Won was paid monthly. On the basis of dry matter 1kg, the prices of TMR products were $325.6{\sim}347.0$Won, whereas those of wet TMR products $365.7{\sim}375.0$Won, which was appeared to be factors to increase management cost. And also, because the TMR plants did not provide TDN (total digestible nutrient) value on their products, nutritional balance feeding for cows could not be managed in farms. It was calculated, based on ADF (acid detergent fiber) value, that TDN value in dry type TMR was 63.0% and 73.2% fur private and cooperation TMR plants, respectively and that the corresponding figure in wet type TMR was 64.9% and 67.2%. According to TMR plant employee's opinion, a prier items to enlarge TMR utilization were TMR education, TMR advertisement, and improvement of ability to make TMR formula. Therefore, for the purpose of further development of TMR, special education of persons related to TMR should be supported.

• Journal of Environmental Policy
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• v.10 no.3
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• pp.21-48
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• 2011

The paper affirms the weight proportion concept as an element, which could be empirically analyzed quantitatively through the developmental expansion of qualitative empirical analysis on taxonomy that is required for the construction Low-Carbon Green Cities and their eco-friendly elements, such as a pleasant residential environment The weight proportion concept is proposed as a new measure to identify eco-friendly elements and as an objective assessment indicators. To perform an empirical analysis, surveys were first given to the residents of Metropolitan Newtown (50 persons) and outside experts (50 persons) for the total of 100 persons. Second, the paper surveyed 74 sites of Eco-Environmental Certified Apartment Housing Complexes. Upon analysis of eco-friendly elements by their type and total weight, the largest weight proportion was expressed in the interior and eco-environmental elements, carbon-decrease types, and carbon-absorption types. The results of this paper confirm recent positive sentiments and preference toward a variety of future-oriented and sustainable eco-friendly elements like the eco-housing and new renewable energy, In addition, the paper affirmed the new housing trend towards constructing eco-friendly elements, such as carbon-decrease and carbon-absorption, that induce long-term investments, despite their need for higher investments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.1-7
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• 2018

The gases emitted from internal combustion engines using fossil fuels are causing many social problems, such as environmental pollution, global warming, and adverse health effects on the human body. In recent years, the demand for renewable energy has increased, and government policy support and research and development are also active. In the collecting part of a solar energy system, which is widely used at home, propylene glycol (PG) (anti-freeze), as a heating medium, is mixed with water at a fixed value of 50%, and the heat is transferred to the collecting part at subzero temperatures. On the other hand, when leakage occurs in the heat medium in the heat collecting part, supplemental water is supplied to the solar heat collecting part due to the characteristics of the solar heat system, so that the concentration of antifreeze in the replenishing water becomes low. As a result, the temperature of the solar heat collecting part is lowered resulting in a frost wave, which causes economic damage. The purpose of this study was to develop a device capable of controlling the antifreeze concentration automatically in response to a temperature drop to prevent freezing of the heat collecting part generated in the solar energy system. The electrical conductivity of the H2O component was larger than that of PG, and the resistance increased with decreasing temperature. The PG concentration control values of 40, 50, and 60% should be controlled through calibration with a PG concentration of 39.6, 50.7, and 60.1%.