• Ocean Systems Engineering
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• 제8권3호
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• pp.313-327
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• 2018

Meeting the touchdown point (TDP) target box is one of the challenges during catenary riser installation, especially for deep water or ultra-deep water riser systems. TDP location mismatch compared to the design can result in variation of riser configuration, additional hang-off misalignment, and extra bending loads going into the hang-off porch. A good understanding of the key installation parameters can help to minimize this mismatch, and ensure that the riser global response meets the design criteria. This paper focuses on investigating the potential factors that may affect the touchdown point location, and addressing the challenges both in the design stage and during installation campaign. Conventionally, the vessel offset and current are the most critical factors which may affect the TDP movement during installation. With the offshore exploration going deeper and deeper in the sea (up to 10,000ft), other sources such as the seabed slope and seabed soil stiffness are playing an important role as well. The impacts of potential sources are quantified through case studies for steel catenary riser (SCR) and lazy wave steel catenary riser (LWSCR) in deep water application. Investigations through both theoretical study and numerical validation are carried out. Furthermore, design recommendations are provided during execution phase for the TDP mismatch condition to ensure the integrity of the riser system.

• 대한토목학회논문집
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• 제41권1호
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• pp.57-64
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• 2021

도시부도로에서 변속차로는 도로가 연결되는 지점에 설치되어 상대속도를 낮추도록 함으로써 교통소통을 원활하게 하고 있다. 그러나 도심내 안전 속도 "5030"시행에 따른 제한속도 30 km/h의 경우 기준이 모호하여 변속차로 설치에 대한 지적이 나오고 있다. 본 연구는 변속차로에 대한 이론적 고찰 후 안전속도 "5030" 정책 시행 예정 구간을 중심으로 변속차로 통행패턴을 사례조사를 실시하였다. 현장조사 후 도로조건 및 교통 조건 등에 따라 주도로의 통행 속도별 통행 패턴을 분석한 결과 안전속도 "5030"시행에 따른 변속차로의 실효성을 분석하였다. 본 연구수행을 통해 제시된 속도별 변속차로 설치기준은, 통행속도 30 km/h 구간인 경우는 변속차로를 미설치 하도록 하고, 50 km/h인 경우는 반드시 설치토록 하는 기준을 제시하였다. 향후 도시지역에서 다른 시설의 연결에 대한 공학적 기준을 정립할 때 참고할 수 있을 것으로 판단되며, 변속차로 설치 및 회전반경 확대를 통한 속도별 원활한 교통소통 및 안전성을 확보하고 개인의 사유재산권 행사에 대한 불필요한 제약을 최소화하는데 기여할 수 있을 것으로 기대된다.

• 조명전기설비학회논문지
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• 제30권3호
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• pp.53-58
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• 2016

The underground transmission lines which have been built to expand the suppling facilities will be continuously accompanying with high growth of the increase of power demand in the metropolitan area in recent years. So, it is necessary to maximize the ability and reliability of power supply with the current-carrying capability of the underground transmission lines. Design criteria of KEPCO is to be presented and used frequently. But it has to be studied about the installation methods of power cable buried in ground. In this study, we used the program for calculating the current-carrying capability of underground transmission power cables. We estimated the maximum permissible current values by the horizontal arrangement in the installation methods of power cable(154kV XLPE $600mm^2$) buried ducts in ground. To see the general tendency of the analysis, we researched a statistical analysis with such parameters as the maximum permissible current values. Through the regression analysis, we analyze the most highly values of the maximum permissible current on the Ra type duct arrangement.

• 한국화재소방학회논문지
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• 제30권4호
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• pp.1-5
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• 2016

본 논문은 영상화재감지기(Video Fire Detector)의 시험 및 설치기준에 관한 연구로서 FM Approvals, UL, ISO7240 및 NFPA 72 기준들을 서로 비교분석하여 국가화재안전기준 203 (NFSC 203)에 반영되어야 할 기준들을 제안하였다. 영상화재감지기의 시험과 관계된 FM Approvals 기준에는 연기형, 불꽃형으로 분류되고 비화재보시험이 있었으나 UL 기준에는 연기형만 제시되어 있었다. 외국 기준인 ISO 7240에서는 화재현상 검출유형 등 6가지를, NFPA 72에서는 화재현상 검출유형 등 3가지를 조사하였다. CCTV 설치 표준공법에서는 영상화재감지기의 설치기준에 필요한 항목이 15가지가 있었으며 설치방법에 따라 각 분야별 기준이 제시되어 있었다. 영상화재감지기 적용을 위해서는 감지기 시험항목 중 용어의 정의, 감지기의 구분, 구조 및 기능에 관련항목을 삽입하고 감도조정, 비화재보방지, 주위온도시험, 유효감지거리 및 감도와 시야각, 노화시험, 살수시험, 내화시험의 7개 항목의 적용이 필요하다. 현장 설치를 위해서는 국가화재안전기준 203 (NFSC 203)에 작동환경 및 조도기준을 설정하고 음향장치, 표시등의 설치거리 등의 기준을 삽입하여야 한다.

• 한국도로학회논문집
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• 제14권6호
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• pp.175-182
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• 2012

PURPOSES : This paper presents how to determine priorities of RWIS installation on national highways within the limited budget. METHODS : Analytical hierarchy process was employed to develop the entire methodology. In addition to this, various data such as vulnerable roadway section for snow removal, RWIS, AWS, AADT, and traffic accident were properly collected and analyzed for the future analysis. Then, GIS analysis was performed to find out the final candidate vulnerable roadway section for snow removal. In the end, expert survey was conducted to estimate weights for evaluation criteria. RESULTS : Results showed that metropolitan area has the most high priority, and Gangwon area, ChungCheung, and Honam in order. CONCLUSIONS : The main contribution of this paper is to suggest a logical methodology to prioritize RWIS installation within the limited budget, and thus snow removal operation during the winter season can improve in terms of getting more valuable information.

• Wind and Structures
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• 제14권1호
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• pp.71-80
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• 2011

This study presents a decision making process for installation of wind barrier which is used to reduce the wind speed applied to running vehicles on expressway. To determine whether it is needed to install wind barrier or not, cost and benefit from wind barrier are calculated during lifetime. In obtaining car accidental risk, probabilistic distribution of wind speed, daily traffic volume, mixture ratio in the volume, and duration time for wind speed range are considered. It is recommended to install wind barrier if benefit from the barrier installation exceed construction cost. In the numerical examples, case studies were shown for risk and benefit calculation and main risky regions on Korean highway were all evaluated to identify the number of installation sites.

• 한국유기농업학회지
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• 제22권4호
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• pp.841-854
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• 2014

This study aimed to analyze the selection criteria and priority settings for solid culture medium used in hydroponic crop production in farm households. Expert brain storming was carried out to extract solid culture medium selection criteria for hydroponic farming. As a result, 3 criteria of economy (cost), productivity, and environment, and 9 factors were extracted. A questionnaire survey of hydroponic farm households was conducted in Gyeonggi, Gangwon, and Chooncheong provinces. AHP analysis of the hydroponic solid culture medium selection criteria identified productivity as the most important criterion, chosen by 58.7% of the respondents, followed by economy (28.4%) and environment (12.9%). The 9 factors were rated by the respondents in the following decreasing order of importance: 1, crop yield (28.3%); 2, pest occurrence (18.5%); 3, maintenance/management costs (12.0%); 4, convenience of maintenance/management (13.4%); 5, initial investment cost (11.6%); 6, material energy consumption (6.5%); 7, waste recyclability (4.0%); 8, waste disposal costs (3.4%); and 9 environmental emissions (1.81%). These results imply that hydroponic farm households consider cultivation-related quality factors more important than economic factors, such as price of culture medium or installation cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.74-78
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• 2002

In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.

• 대한전기학회논문지:전력기술부문A
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• 제51권5호
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• pp.238-246
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• 2002

Utilities are trying to install the equipment of high quality to avoid deterioration of supply reliability. In addition, many sectionalizing switches which can decrease the total outage value for a fault are installed for the same reason. Therefore, utilities are interested in stun dards and criteria for installing switches to optimize the total cost on distribution systems. The affect of sectionalizing switches installed on distribution feeder is gradually decreased because the failure rate on distribution feeder is decreased. Also the automation for distribution systems is widely applied for the efficient operation. Therefore, the renewal for installation standards of sectionalizing switches Is required to reflect the current operation situation. The variable data is used to consider the KEPCO's real situation of distribution feeder as follows; the feeder capacity, connecting rate, feeder length, failure rate of distribution feeder, the failure rate of switches, perception time of feeder fault, the restoration time for a faulted section, the transfer time to other feeders, and the switching time. In this study, We propose equations which can determine the number of sectionalizing switches for minimizing the outage and switch installation cost.

• 조명전기설비학회논문지
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• 제24권2호
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• pp.113-119
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• 2010

안전한 접지설계는 사고 시에 대지로 고장전류를 흘려보내는 수단과 인체가 사고기기에 접촉 시에 위험에 노출되지 않도록 하는데 있다. 변압기 중성점 접지는 1선 지락사고 시 중성점전위가 허용치 이하가 되도록 접지되어야 한다. 변압기 외함 접지는 절연사고로 외함에 전류가 흐를 때 인체 허용전압과 전류 이내로 저감시키는 목적으로 사용되고 있다. 본 논문에서는 사고 시 중성점 전위와 접촉전압을 계산하여 배전 변압기의 접지저항 영향을 심도있게 분석하였다.