• Journal of Korea Water Resources Association
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• v.55 no.9
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• pp.687-700
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• 2022

For comprehensively assessment the water resources performance of multi-purpose dams and water supply dams in South Korea, a methodology was proposed to utilize the durational reliability along with the integrated auxiliary indicators including resiliency, dimensionless vulnerability, water resource efficiency, specific inflow, and specific water supply. In addition, for the purpose of sustainable dam operation in the future, a plan to grade the water resources performance was presented to periodically evaluate the performance and determine the priority of each dam's structural or non-structural planning according to the evaluation results. As major results, in the case of Sumjingang Dam, the durational reliability was 99.0%, but the integrated auxiliary index was the lowest of 44 points, which was 5th grade. This means that despite the current high reliability, hydrological changes due to future climate change or regional change of water demand-supply balance can have significant impacts on the water resources performances. In contrast, the Chungju Dam with a durational reliability of 93.0%, which is below the average among all multi-purpose dams, shows the 76 points of the integrated auxiliary index, which is 3^rd highest following the Soyanggang Dam and the Namgang Dam. Nevertheless, due to the size of the basin, the specific inflow is sufficiently high as 185%, so the actual performance could be evaluated relatively high. The water supply dams designed for a single purpose tend to be evaluated relatively high because they have a high proportion of industrial and municipal water supply and have enough room for the supply capacity.

• Journal of Korean Society of Disaster and Security
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• v.16 no.4
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• pp.75-84
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• 2023

Many developing countries face challenges in estimating long-term discharge due to the lack of hydrological data for water supply planning, making it difficult to establish a rational water supply plan for decision-making on water distribution. The study area, the Bandung region in Indonesia, is experiencing rapid urbanization and population concentration, leading to a severe shortage of freshwater. The absence of water reservoir prediction methods has resulted in a water supply rate of approximately 20%. In this study, we aimed to propose an approach for predicting water reservoirs in developing countries by analyzing water safety and potential water supply using the MODSIM (Modified SIMYLD) network model. To assess the suitability of the MODSIM model, we applied the unit hydrograph method to calculate long-term discharge based on 19 years of discharge data (2002-2020) from the Pataruman observation station. The analysis confirmed alignment with the existing monthly optimal operation curve. The analysis of power plant capacity revealed a difference of approximately 0.30% to 0.50%, and the water intake safety at the Pataruman point showed 1.64% for Q95% flow and 0.47% for Q355 flow higher. Operational efficiency, compared to the existing reservoir optimal operation curve, was measured at around 1%, confirming the potential of using the MODSIM network model for water supply evaluation and the need for water supply facilities.

• Journal of Software Assessment and Valuation
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• v.16 no.2
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• pp.153-162
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• 2020

Digital image forgery detection is one of very important fields in the field of digital forensics. As the forged images change naturally through the advancement of technology, it has made it difficult to detect forged images. In this paper, we use passive forgery detection for copy paste forgery in digital images. In addition, it detects copy-paste forgery using the L₀ Norm-based LE operator, and compares the detection accuracy with the forgery detection using the existing L₂, L₁ Norm-based LE operator. In comparison of detection rates, the proposed lower triangular(Ayalneh and Choi) window was more robust to BAG mismatch detection than the conventional window filter. In addition, in the case of using the lower triangular window, the performance of image forgery detection was measured increasingly higher as the L₂, L₁ and L₀ Norm LE operator was performed.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.246-250
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• 2004

국내 수자원의 지역적 불균형으로 가뭄 시 해안 지역은 제한급수지역의 대부분을 차지하였다(건교부, 2001). 또한 해안지역의 평균 상수도 보급률은 $40\%$대로서 전국 평균 $87.1\%$(환경부, 2001)의 절반 정도이다. 실제로 해안지역의 지하수 이용량은 전국 지하수 이용량 약 31억$m^3$/년(수자원공사, 2002)의 약 $21\%$를 차지하고 있지만, 1인당 지하수 이용량은 전국 평균 $65m^3$의 4배에 달하는 것으로 조사된 바가 있다(홍성훈, 2003). 즉, 용수공급원의 부족으로 해안지역에서는 지하수에 대한 의존도가 높으며, 이로 인해 해안 지역에서 무분별한 지하수 개발과 그로 인한 해수침입 등의 환경 장애와 더불어 폐공 발생수가 증가하고 있는 실정이다. 따라서, 이런 문제점들과 해안지역을 고려한 지하수의 지속적 확보가 절실히 필요하다. 국외 인구동향을 보면 밀도류나 해수침투와 같은 해안지역 특성을 고려한 지하수 최적개발 모델이 개랄 또는 적용되어지고 있다. 하지만 해안지역 지하수 개랄 및 관리에서 요구하는 다양한 충족조건 내신 하나의 목적함수(예를 들어 최적 양수량, 최적 비용 등)만을 고려하고 있다. 그렇지만 실제적인 문제에서는 어느 위치에서 얼마만큼 개발되어야 하는지를 고려해야만 한다. 따라서 본 연구에서는 관정의 최적 개발량과 치적 위치라는 두개의 최적해를 고려할 수 있는 최적 양수모델을 제시하고, 실험실 수리모형에서의 검증을 소개하고자 한다. 또한 해안 지하수의 지속적 확보를 위한 방안을 제시하고자 한다.

• Journal of Sericultural and Entomological Science
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• v.25 no.2
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• pp.44-50
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• 1984

The effects of sodium pyrophosphate, sodium tripolyphosposphate and ethylene diamine tetraacetic acid as a degumming aid reagent were investigated under the conditions of underground water and dimineralized water for the scouring water sources. The changes of water qualities by adding the condensed sodium phosphates and the physical properties of scoured silk fabric were examined, respectively. 1. The water hardness of underground water was decreased by adding the condensed sodium phosphates and it was further reduced according to the increasing temperature. The water hardness reducing power of sodium pyrophosphate was a little stronger than that of sodium tripolyphosphate. 2. The sodium silicate as an alkaline reagant for scouring decreased the water hardness, but the sodium carbonate increased it in the underground water. 3. The pH value of 0.4% soap and 0.25% sodium silicate mixed solution after boiling was. 9.80, but it was leveled upto 9.90 by adding 0.05% sodium pyrophosphate and upto 9.95 by 0.02% ehtylene diamine tetraacetic acid, respectively. 4. The masking action of Fe$\^$3+/ ions dissolved in the scouring water was more remarkable by ethylene diamine tetraacetic acid than by the condensed sodium phosphates. Of the condensations, sodium tripolyphosphate was more effective than sodium pyrophosphate in the action. 5. Genrally, the dimineralized water scouring increased the boil-off ratio with reducing the flexural rigidity of fabric which was negatively related with the favorablility of hand-touch more than the underground one did. 6. Under the underground water scouring, the addition of ethylene diamine tetraacetic acid increased the boil-of ratio and compressive elasticity of fabric with reducing the flexural rigidity more than that of the condensed sodium phosphates did. 7 The additions of sodium tripolyphosphate and ethylene diamine tetraacetic acid reduced the flexural rigidity of fabric with raising the boil-off ratio even in the dimineralized water scouring, but there was no sifnificant difference between both of them.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.704-709
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• 2007

The purpose of this study is to present both problems and improvement plans on the bidding system of the Korea National Housing Corporation, which orders apartment houses professionally. For data gathering, this study used data from electronic procurement system from 2001 to 2005. The research method of this study is to analyze the data categorized into four types: changes of ordering and contract price ration, the lowest-pricing bidding system, and permanent projects by grades. As a result of the analysis, the amount of ordering is biased in favor of particular level. Finally, this study present following improvement plans: 1) screening system and the lowest-pricing bidding system need to be supplemented, 2) the contract price ratio and the amount of ordering should be controlled, and 3) the improvement of PQ and the introduction of the list of Qualified companies by types need to be presented.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.360-368
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• 2013

Recently interactive water fountains are gaining popularity in making public facilities in South Korea. The total number of interactive fountains is rapidly growing at the rate of >50% annually. In this study, we performed quantitative microbial risk assessment to estimate infection risks in children by Legionella spp. while playing in interactive fountains. The exposure dose for a given concentration of Legionella in water was calculated using water-aerosol partition rate of Legionella, exposure duration, inhalation rate, and deposit rate of aerosols in the lungs following inhalation. The dose was converted to infection risk by using the dose-response function developed for L. pneumophila. High weight and/or old children, i.e., 12-year children, running around in fountains were the highest risk group by showing >0.05 infection probability for fountain waters containing ${\geq}10^4$ CFU/L Legionella. The result supported the current guideline by Korea Centers for Disease Control and Prevention, which permits use of water with < $10^3$ CFU/L Legionella cells for all purposes. However, the results still warrant further evaluation of the guideline to accommodate risks for children because the dose-response relationship in the model was developed for healthy adults. Further risk assessment studies need to be conducted by employing dose-response model for children who generally carries weaker immune system than adults.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.234-234
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• 2018

댐 건설을 하게 되면 저수지 형성으로 인한 통수단면 증가가 발생하고 이에 따른 하천의 유속 및 난류 영향이 감소하게 된다. 이러한 영향으로 댐 상류 구간에서 발생한 유사량은 저수지에 퇴적하게 되고 유효저수량은 감소하게 된다. 저수지의 유효저수량 감소는 댐의 주요 기능인 용수공급, 수력발전 등의 기능 저하에 지대한 영향을 주게 된다. 특히 해외 수력발전 사업의 경우 하천 경사가 크고, 퇴사가 많이 발생하는 지역에 댐이 위치하고 있다. 이와 같은 문제 해결을 위한 중 장기적 퇴사거동 및 예측에 대한 연구가 필요한 상황이다. 본 연구에서는 파키스탄 Gulpur 지역에 설치 예정인 수력발전용 댐에 대한 장기간 퇴사모의를 위해 1차원 유사해석 모형인 HEC-RAS sediment module을 이용하였다. 퇴사모의에 적용한 모형의 입력 자료로는 총 52개년(1960-2011년)간 유사량 관측값과 20년간 유량측정 결과를 이용하였다. 유사해석 모의 시나리오는 유사 재질 비율변화에 따른 장기간 Deposited 모의와 댐의 Gate를 통한 유사 배제를 운영하는 Flushing 모의를 수행하였다. 유사해석 모의 결과 Deposited 시나리오의 경우는 저수지에서 퇴적된 유사는 대부분 Sand가 차지하게 된다. Sand의 포착률은 저수지가 가득 차기 이전에는 거의 100 % 포착이 되며, 저수지가 가득 차는 시기인 운영 20년 후에는 Sand를 포함한 전체 유사의 59%가 포착하게 되어 저수지가 한계에 도달한 것을 확인하였다. 또한, Flushing 시나리오의 경우는 Flushing 운영 기간의 변화에 따른 퇴사 포착 영향이 큰 것으로 분석되었으며, Gulpur 댐의 경우는 운영기간을 5일로 설정하는 것이 안정한 하상상태를 유지하는 것으로 검토되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.1
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• pp.41-49
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• 2018

This study is to analyze and evaluate water resource development potential in North Korea. The study was conducted to analyze selected potential hydropower as an indicator to evaluate water resource development potential. Potential hydropower means theoretical value about the potential capacity of river. It is used to evaluate the amount of development through the hydropower generation. For calculating potential hydropower, monthly average and annual average of rainfall for each river basin were calculated by using the data of 27 rainfall stations in North Korea. As a result of the calculation of theoretical potential hydropower by rainfall in the seven major basins in North Korea, the Aprok River basin was analyzed to be the largest with $7,562.2{\times}10^3kW$. The efficiency and utilization rate of theoretical potential hydraulic power in South Korea and North Korea was 42.3% and 36.2%, respectively. The Daedong River basin's potential hydropower utilization rate is 12.3%, which is the lowest in North Korea. In the case of Daedong River basin, more than 40% of the total population is inhabited, so demand for water and electricity is expected to be the largest. Therefore, the Daedong River basin is considered as a priority area for water resource development. The results of this study are expected to be used as basic data for future water resource development projects and research activities in North Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.239-247
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• 2003

This paper presents a dual-rate (2.4/4.0 kbps) Improved Harmonic-CELP(IHC) speech coder based on the EHC(Efficient Harmonic-CELP) which was presented by the authors. The proposed IHC employs the harmonic coding for voiced and the CELP for unvoiced segments. In the IHC, an initial voiced/unvoiced estimate is obtained by the pitch gain and energy. Then, the final V/UV mode is decided by using the frame energy contour. A new harmonic estimation combining peak picking and delta adjustment provides a more reliable harmonic estimation than that in the EHC. In addition, a noise mixing scheme in conjunction with an improved band voicing measurement provides the naturalness of the synthesized speech. To demonstrate the performance of the proposed IHC coder, the coder has been implemented and compared with the 2.0/4.0 kbps HVXC(Harmonic excitation Vector Coding) standardized by MPEG-4. Results of subjective evaluation showed that the proposed IHC coder and produce better speech quality than the HVXC, with only 40% complexity of the HVXC.