• 한국가구학회지
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• 제20권4호
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• pp.358-373
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• 2009

Probability based design(PBD)method has some advantages against current design methods. First, it can provide the quantitative values for the structural safety or capacity through the reliability index, $^{\beta}$. That presented the certainty on the corresponding structure for the designer or user, also that permitted the broad consideration in the safety of structures. In addition, it can give the quantitative lifetime of the related structure in the calculation process of target reliability index. Also, incidental economical efficiency can be expected because decrease of required structural material can be obtained by using the practical material data. Unlikely current deterministic structural design methods, main advantage is the reflection of real condition in the structural design process by application of the data with not small clear specimen but structural size material. Advanced countries, namely America, Canada, Europe, Australia and New Zealand already converted from allowable stress design(ASD) method to PBD method and used as a standard wooden structures code in the late 1980s and 1990s. Other domestic constructions standards such as the steel or concrete constructions accepted and used the PBD methods already. Accordingly, wooden structural design method also should be converted from deterministic ASD to probabilistic LRFD(Load and resistance factor design) in order to keep pace with worldwide demands for PBD. Hence, to suggest the reason of introduction the PBD in domestic wooden structural design and analysis, a brief example was used to show the different reliability index by using the different design methods. Definition, merits and demerits of deterministic ASD and probabilistic LRFD were followed. Also the three examples were presented to show the similarity and differences between ASD and LRFD. Finally, connection problems that might cause a disputation in wooden structural design and analysis were broadly examined.

• 한국측량학회지
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• 제35권6호
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• pp.509-516
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• 2017

지적측량의 경우 수치측량을 실시하는 지역에서는 사실상 면적오차를 허용하고 있지 않으며, 도해측량을 실시하는 지역에서는 필지 형상과 무관하게 면적오차를 규정하고 있다는 문제점이 있다. 본 연구에서는 이 두 가지 문제점의 파악에 필요한 면적오차의 일반식을 도출하였다. 이 수식을 이용한 계산에 의하면, 현실적으로 지적재조사 사업의 필지경계점의 좌표오차를 5cm+10ppm으로 둘 경우, $100 m^2$ 필지라 해도 면적오차가 $0.71m^2$ 로서 무시할 수 없는 것으로 나타났다. 또, 지적법시행령에서 규정한 면적오차는 경계점 오차를 ${\sigma}_o=0.3mm{\times}$ 도면축척으로 둘 경우 변장 비율이 1:5인 직사각형의 면적오차와 일치하였다. 이러한 결과는, 다각형 필지의 면적오차는 경계점 좌표의 오차 크기를 지정함으로써 측량 방법을 구분하지 않고 하나의 수식에 의해 면적오차의 허용범위를 정할 수 있다는 것으로, 지적측량의 면적오차를 규정하는 현행 규정을 합리적으로 개정하는 데에 활용될 수 있다.

• 콘크리트학회논문집
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• 제14권6호
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• pp.961-972
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• 2002

횡하중을 받는 플랫 플레이트 구조는 슬래브-기둥 접합부의 취성 전단파괴에 대하여 취약하며, 이러한 접합부의 취성적 파괴를 방지하기 위해 접합부의 강도 및 연성능력이 반드시 확보되어야 한다. 그러나 이전 연구에 의하면 현행 설계기준이 플레이트-기둥 접합부의 강도를 정확히 예측하지 못하는 것으로 밝혀졌다. 본 연구에서는 비선형 유한요소해석을 이용한 변수연구를 내부 접합부에 대해 실시하였으며 수치해석 결과에 근거하여 접합부에 대한 설계방법을 개발하였다. 접합부 주위의 위험단면에서는 중력하중과 횡하중에 의해 발생된 휨모멘트와 전단력이 공존하며, 이 휨모멘트와 전단력의 상호작용을 고려하여 최대 허용편심전단응력을 제안하였다. 제안된 강도모델은 현 설계기준에 비하여 접합부의 강도를 보다 정확히 산정 할 수 있으며, 연속 슬래브에 대한 비선형 해석결과와 기존의 실험결과와의 비교를 통해 그 유효성을 검증하였다.

• 전기전자학회논문지
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• 제15권3호
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• pp.218-226
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• 2011

본 논문은 현재 유선방송 기술기준에서 CDMA 이동통신서비스 대역의 누설전자파 기준이 적절한지를 검증하고자 하였다. 먼저, CDMA 2000 1X 기지국 장비를 통한 실험결과로부터 CDMA 이동통신 시스템의 최대 허용 간섭 레벨은 -110dBm/1.23MHz인 것으로 분석되었다. 이를 토대로 이동통신기지국에 거의 영향을 주지 않을 케이블 방송 옥외 전송설비의 누설 간섭전력의 임계레벨과 누설전자파 세기를 산출하였다. 일반적으로 옥외에서 측정되는 외부시스템의 배경 간섭레벨인 -100~-80dBm/1.23MHz에 대해서 허용될 수 있는 케이블 방송 설비의 누설전자파 임계치는 현행 유선방송 기술기준을 만족시키지 못하였다. 이것은 현행 기술기준이 지나치게 최악의 경우를 상정하여 설정되었음을 의미하므로 이동통신사업자의 실제적인 기지국 조건을 적용하여 합리적인 기술기준을 마련하여야 할 것이다.

• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.287-294
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• 2017

EVs manufacturers typically target a range of 300 km on a fully charged battery. Many studies have been conducted to improve these disadvantages. As a results, the mileage of EVs is expected to increase significantly. However, as the distance traveled by EVs increases, current test method (SCT) have many difficulties. The biggest problem is that it takes a lot of time to test an EVs and greatly increases the error rate during the test period. In order to solve these problems, this paper discusses the fuel economy test method of EVs for energy efficiency and mileage. The comparison of test methods was achieved by chassis dynamometer test about EVs. These review of test methods are intended to both improve testing efficiency and provide a practical testing methodology that can be easily adapted to accommodate future testing enhancements. In conclusion, the results of MCT mode and SCT mode comparison show similar results within 3 %, confirming that the test method is appropriate. Also, as the CSCM distance becomes shorter in the MCT mode, the mileage becomes longer and the fuel economy becomes lower. As a result, the error from the SCT test results is expected to increase. In order to minimize the error of SCT measurement fuel economy, it is recommended to maximize the CSCM driving distance. However, since the timing of the EOT is not clearly known, it is reasonable to define the allowable range of the CSCE to be within 20 % of the MCT total mileage.

• 대한토목학회논문집
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• 제6권4호
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• pp.61-68
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• 1986

본(本) 연구(硏究)에서는 철근(鐵筋)콘크리트 구조(構造)에 대하여 확률이론(確率理論)에 기초(基礎)한 허용응력(許容應力) 설계규준(設計規準)의 개발(開發)을 위한 방법(方法)을 제시(提示)하였다. 철근(鐵筋)콘크리트 구조부재(構造部材)의 신뢰성지수(信賴性指數)는 AFOSM 신뢰성(信賴性) 해석법(解析法)을 사용하여 계산(計算)하였으며, 또한 시방서(示方書) 신뢰성(信賴性) 검정(檢定)의 실용적(實用的) 방법(方法)을 제시(提示)하였다. 각(各) 구조요소별(構造要素別) 목표신뢰성지수(目標信賴性指數)는 현행(現行) 규준(規準)에 의해 설계(設計)된 구조물(構造物)의 안전성(安全性)에 관한 수치적(數値的) 연구결과(硏究結果)를 고려하고 또 현(現) 실정(實情)을 반영하여 결정(決定)되었다. 현행(現行) WSD 안전규정(安全規正)을 대치(代置) 사용(使用) 가능토록 본(本) 연구(硏究)에서는 합리적(合理的) 목표신뢰성지수(目標信賴性指數)에 기초(基礎)하여 R.C. 각(各) 구조요소별(構造要素別) 허용응력(許容應力) 및 안전계수(安全係數)를 제안(提案)하였다.

• 한국항해항만학회지
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• 제38권3호
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• pp.253-259
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• 2014

최근 선박의 대형화 고속화가 진행되면서 항만의 변화와 항내 수역 혼잡의 증대 등 해상 교통에 많은 위험 요소가 늘어가고 있다. 최근 가장 첨예하게 대립되는 것이 항로폭을 적정하게 결정하는 문제이다. 현행의 항로폭 설계법은 해당 수역을 통항하는 최대 선박의 운동 성능을 중심으로 설계되고 있지만, 다양한 종류의 선박이 혼재되어 운항하고 있는 해상교통 환경을 고려하지 않고 있다. 본 연구에서는 항내 수역의 다양한 교통 상황을 설정하고, 교통(용)량을 고려한 항로 설계법을 제안하고 이를 현행 항로설계법과 비교하였다. 이를 위해 기존 항로 설계 방법을 정리하고, 항내 수역을 대상으로 하는 162개의 해상교통 시뮬레이션을 실시하였다. 이 결과를 바탕으로 각 선종별 선형 구성 및 교통량에 따른 환경스트레스값 즉 운항위험도를 추정하였다. 허용 교통량에 대한 적정 항로폭 모델식을 구하고, 실제 수역에 적용하였다. 현행 설계법에 따른 항로폭과 비교하고 그 유용성을 확인하였다.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.55-60
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• 2015

PG and RG methods are widely known method for calculating the capacity of the emergency generator in construction electrical installation. PG and RG methods are mainly used as a saving a life, fire protection, fire fighting in construction. Because no long distance between the emergency generator and electric motor feeder, the relatively small motor power in construction electrical installation, the capacity of generator in PG and RG methods are little problem of voltage and reactive power of generator. However in many cases the application of the PG and RG method is difficult in the Chemical Plant because it is long distance between the generator and the motor Feeder and motor capacity is very large. Motor starting power factor is about 0.2 lagging power factor and motor starting current is about 6times during motor staring. Also Most of the staring current component is a reactive power component. therefore, it is many cases that lack of reactive power and excess of allowable voltage drop limit and After selection of emergency diesel generator, problems happen during motor starting. Therefore, to be selection of effective emergency generator, active generator power, reactive power and the required reactive power during large motor starting should be considered in chemical plant. It is also required of the verification process through simulation because hand calculation is very difficult considering study cases.

• Ocean Systems Engineering
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• 제2권3호
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• pp.217-228
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• 2012

As the size of container ships continues to increase, not many existing harbors can host the super-container ship due to its increased draft and the corresponding dredging requires huge budget. In addition, the minimization of waiting and loading/offloading time is the most important factor in harbor competitiveness. In this regard, mobile-harbor concept has been developed in Korea to achieve much improved harbor capacity and efficiency. In developing the concept, one of the most important elements is the operability of crane between two or more floating bodies in side-by-side arrangement. The container ship is to be stationed through a hawser connection to an outside-harbor fixed-pile station with the depth allowing its large draft. The mobile harbors with smart cranes are berthed to the sides of its hull for loading/offloading containers and transportation. For successful operation, the relative motions between the two or more floating bodies with hawser/fender connections have to be within allowable range. Therefore, the reliable prediction of the relative motions of the multiple floating bodies with realistic mooring system is essential to find the best hull particulars, hawser/mooring/fender arrangement, and crane/docking-station design. Time-domain multi-hull-mooring coupled dynamic analysis program is used to assess the hydrodynamic interactions among the multiple floating bodies and the global performance of the system. Both collinear and non-collinear wind-wave-current environments are applied to the system. It is found that the non-collinear case can equally be functional in dynamics view compared to the collinear case but undesirable phenomena associated with vessel responses and hawser tensions can also happen at certain conditions, so more care needs to be taken.

• Safety and Health at Work
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• 제11권4호
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• pp.405-417
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• 2020

Background: Electrical socket outlets are used continuously until a failure occurs because they have no indication of manufacturing date or exchange specifications. For this reason, 659 electrical fires related to electrical socket outlets broke out in the Republic of Korea at 2018 only, an increase year on year. To reduce electrical fires from electrical socket outlets, it is necessary to perform an accelerated test and analyze the thermal, insulation resistance, and material properties of electrical socket outlets by installation years. Methods: Thermal characteristics were investigated by measured the temperature increase of electrical socket outlets classified according to year with variation of the current level. Insulation resistance characteristics was measured according to temperature for an electrical socket outlets by their years of use. Finally, to investigate the thermal and insulation resistance characteristics in relation to outlet aging, this study analyzed electrical socket outlets' conductor surface and content, insulator weight, and thermal deformation temperature. Results: Analysis showed, regarding the thermal characteristics, that electrical socket outlet temperature rose when the current value increased. Moreover, the longer the time that had elapsed since an accelerated test and installation, the higher the electrical socket outlet temperature was. With respect to the insulation resistance properties, the accelerated test (30 years) showed that insulation resistance decreased from 110 ℃. In relation to the installation year (30 years), insulation resistance decreased from 70 ℃, which is as much as 40 ℃ lower than the result found by the accelerated test. Regarding the material properties, the longer the elapsed time since installation, the rougher the surface of conductor contact point was, and cracks increased. Conclusion: The 30-year-old electrical socket outlet exceeded the allowable temperature which is 65 ℃ of the electrical contacts at 10 A, and the insulation resistance began to decrease at 70 ℃. It is necessary to manage electrical socket outlets that have been installed for a long time.