• 상하수도학회지
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• 제26권3호
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• pp.443-451
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• 2012

Wastewater treatment plants need to reduce phosphorus in order to meet increasingly stringent regulations on phosphorus. This study evaluated the feasibility of dolomite as a coagulation aid to enhance phosphorus removal from secondary treated wastewater by chemical coagulation. Standard jar tests were conducted to evaluate the effect of dolomite addition on a coagulation process for phosphorus removal and to determine the optimum doses of coagulants and dolomite. Coagulants used with dolomite yielded a significant improvement in phosphorus removal and reduced total phosphorus concentrations below 0.02 mg/L in wastewater effluent. Dolomite has played an important role in enhancing phosphate adsorption and increasing pH, as a coagulation aid. The maximum removal efficiency of phosphorus in this study was yielded at 25 mg/l of dolomite and 20 mg Al/L of PAC dose. However, considering economic aspects, the optimum doses of dolomite and PAC were 10 mg/L and 15mg Al/L, respectively. Consequently, dolomite, a coagulation aid, can be used in coagulation processes to enhance the removal of phosphorus.

• Architectural research
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• 제22권2호
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• pp.53-61
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• 2020

The purpose of this study is to examine the influence of remoteness between exit stairways on evacuation performance. Firstly, we reviewed the design regulations of the U.S., the U.K., and South Korea, in relation to remoteness between Exit stairways. Secondly, evacuation simulation was implemented, in order to evaluate the adequacy of each standard. Eight tall buildings in South Korea were selected for the simulation. Evacuation performance was assessed for different remote distances between Exit stairways. Lastly, this research analyses the evacuation simulation data statistically in relation to the effect of remoteness on evacuation time. We found that as the distance between two exit stairways increases, the total evacuation time and average evacuation time for evacuees decreases. There was no statistical influence between the maximum travel distance of the evacuee and the remoteness between two exit stairways, but there was a significant effect on the average travel distance of the evacuees. In addition, the results from the optimal point showed that the L_ratio had the highest evacuation time at 0.44, while the D_ratio had the highest evacuation time at 0.38.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1471-1480
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• 2020

This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 ㎍/L U: 492 USD/g-U) outperformed the aluminum system (96 ㎍/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 ㎍/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/㎠, respectively. The fuzzy optimal solution reveals the following: uranium concentration - 5 ㎍/L, cumulative uncertainty - 25 ㎍/L, energy consumption - 461.7 kWh/g-U and operational cost based on electricity cost in the United States - 60.0 USD/g-U, South Korea - 55.4 USD/g-U and Finland - 78.5 USD/g-U.

• 한국해양공학회지
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• 제27권1호
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• pp.9-15
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• 2013

This paper calculates the mating dynamic forces of a semi-submersible offshore structure's topside module, where a hull moored in the sea is combined with a topside module carried by a heavy lift vessel, as a mating installation method. The environmental conditions include various wave directions and wave heights, with constant wind and current speeds. Appropriate ballast and de-ballast plans for the heavy lift vessel and hull of the semi-rig should be performed in order to safely obtain these forces, whereas a fixed platform or the GBS (Gravity based structure) type of offshore structure only needs a ballast plan for the heavy lift vessel. From this paper, the allowable wave height or wave direction for the mating procedure can be investigated based on the standard DAF (Dynamic amplitude factor) of the rules and regulations.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.468-471
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• 2004

입주자의 선호도를 무시한 획일적 평면의 공급으로 인해 공동주택 발코니 개조가 심각한 수준에 이르고 있으며, 이로 인해 국가적 손실과 많은 문제점을 유발하고 있다. 지금까지의 많은 선행 연구들은 발코니의 사용실태, 발코니의 개조비율과 개조유형을 조사하여 평면계획상의 개선방안만을 거론하였을 뿐, 개조비용을 산출한 연구는 전무하다. 따라서 본 연구는 첫째, 설문을 통해 발코니의 개조비용을 추정하고, 둘째, 건설회사 분양방식, 거주자의 의식, 관련법령 측면에서 발코니 개조 원인을 분석함으로써, 각 측면에서 발코니 개조를 양성화할 수 있는 방안을 제안하였다.

• ETRI Journal
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• 제39권3호
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• pp.373-382
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• 2017

A new internally compensated low drop-out voltage regulator based on the cascoded flipped voltage follower is presented in this paper. Adaptive biasing current and fast charging/discharging paths have been added to rapidly charge and discharge the parasitic capacitance of the pass transistor gate, thus improving the transient response. The proposed regulator was designed with standard 65-nm CMOS technology. Measurements show load and line regulations of $433.80{\mu}V/mA$ and 5.61 mV/V, respectively. Furthermore, the output voltage spikes are kept under 76 mV for 0.1 mA to 100 mA load variations and 0.9 V to 1.2 V line variations with rise and fall times of $1{\mu}s$. The total current consumption is $17.88{\mu}V/mA$ (for a 0.9 V supply voltage).

• 한국항공우주학회지
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• 제45권7호
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• pp.566-573
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• 2017

항공기의 설계 안전성을 보장하기 위하여 형식증명을 받아야 한다. 형식증명을 받은 항공기의 설계가 중대하게 변경되는 경우, 형식증명을 새로 받거나 개정형식증명 또는 부가형식증명을 신청하여야 한다. 국제민간항공기구, 미국 및 유럽의 인증 규정에서 부가형식증명 대상이 되는 설계변경에 대하여 매우 추상적으로 정의하고 있으므로, 본 논문에서는 설계변경에 관한 세계 각국의 인증절차와 인증사례를 분석하여 부가형식증명 대상이 되는 "광범위하지 않은 중급 설계변경"을 판단하는 기준을 제시하였다.

• 대한공간정보학회지
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• 제13권4호
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• pp.47-58
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• 2005

전라남도 곡성군 남부에 위치한 원등지역에서 기반암의 품질을 검토하고 지리정보시스템(GIS)을 이용하여 개발난이도를 분석하였다. 기반암의 품질을 알기 위하여 야외조사를 수행하였고, 실내에서 물성을 분석하였다. 또한 GIS를 이용한 개발난이도 분석에서 가시권분석과 거리분석을 통해 법적개발제한지역을 분석하였다. 원등일대 연구지역의 기반암 품질과 개발난이도를 분석한 결과, 모두 개발이 가능한 품질을 가지고 있으며, 개발제한사항에 해당되는 정도에 따라 개발난이도가 구분되었다. 또한 개발 난이도가 가장 낮은 조사지역의 약 30 % 지역이 개발 가능한 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제58권1호
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• pp.121-142
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• 2016

The national standard being used in Turkey for suspended ceiling systems (SCS) regulates material and dimensional properties but does not contain regulations regarding installation instructions which cause substandard applications of SCSs in practice. The lack of installation instructions would potentially affect the dynamic performance of these systems. Also, the vast majority of these systems are manufactured using substandard low-quality materials, and this will inevitably increase SCS related damages during earthquakes. The experimental work presented here focuses on the issue of dynamic performance of SCSs with different types of carrier systems (lay-on and clip-in systems), different weight conditions, and material-workmanship qualities. Moreover, the effects of auxiliary fastening elements, so called seismic perimeter clips, in improving the dynamic performance of SCSs were experimentally investigated. Results show that clip-in ceiling system performs better than lay-on system regardless of material and workmanship qualities. On the other hand, the quality aspect becomes the most important parameter in affecting the dynamic performance of lay-on type systems as opposed to tile weights and usage of perimeter clips. When high quality system is used, tile weight does not change the performance of lay-on system, however in poor quality system, tile weight becomes an important factor where heavier tiles considerably decrease the performance level. Perimeter clips marginally increase the dynamic performance of lay-on ceiling system, but it has no effect on the clip-in ceiling system under the shaking levels considered.

• 한국터널지하공간학회 논문집
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• 제13권1호
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• pp.1-8
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• 2011

장대 도로터널 및 위험도가 높은 도로터널에 설치되고 있는 물분무소화설비는 성능과 관계된 단위면적당 방수밀도에 대한 검증과정이 없이 사용되어 왔다. 본 연구는 도로터널에 물분무소화설비에 노즐을 설치하여 기준압력에서 방수시험을 실시하여 기준을 만족하는지 여부를 확인하였다. 결론적으로 모든 노즐이 기준을 만족하지 못하였다. 이런 결과는 도로터널용 물분무노즐을 검증하는 시험기준이 없고, 실제 시험을 통한 검증 과정이 존재하지 않았기 때문이라고 판단된다. 따라서 물분무노즐의 성능을 시험할 수 있는 기준의 마련과 설치된 시설을 검증하는 제도적인 보완이 필요하다.