• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1428-1429
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• 2008

In this study the formula of electromagnetic field s by dipole antenna theory were applied to 3 phase power lines and effect of over-head earth lines was calculated and analyzed.

• 대한안전경영과학회지
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• 제26권1호
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• pp.9-14
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• 2024

Restraints of Branch Lines are used as earthquake-resistant support devices for fire-fighting pipes along with sway brace devices. The central types are aligned and fixed in a straight line with center of the pipe, but the eccentric types are fixed to on side of the pipe, so a bending moment occurs. In this study, three specimens each of central type and eccentric type were installed at an angle of 45° from the vertical and a monotonic compression load of 1340N was applied. All central type samples satisfied 17.8mm of the allowable displacement, but all eccentric type samples failed to meet the target load and buckled. Therefore, when considering the performance of eccentric type restraints, both compressive load and bending moment must be considered. Even through material mechanics calculations, the yield stress of eccentric type - 3/8 inch all threaded steel bolt - exceeds 320Mpa of the allowable stress. A experiment standards need to be established for eccentric type restraints.

• 문화기술의 융합
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• 제5권4호
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• pp.11-21
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• 2019

이 연구는 완강기 및 간이완강기의 설치 및 유지관리에 대해 지도 감독해야 할 책임이 있는 공무원을 대상으로 숙박시설의 화재발생시 완강기, 간이완강기의 인지 및 사용능력을 평가하기 위한 것으로 주요 연구결과를 요약하면 다음과 같다. 첫째, 완강기와 간이완강기를 구분할 수 있는 능력 비교에서 일반 행정직공무원 중 여성공무원의 대다수가 간이완강기 구분능력이 없기 때문에 이들의 완강기 구분 능력을 향상시켜서 유사시 추락 등 안전사고를 예방하기 위하여 안전체험관 등을 통해 정기적으로 교육을 받을 수 있도록 제도적 장치가 필요하다. 둘째, 성별과 직업별 간이완강기의 재사용여부를 직업별로 확인한 결과 소방공무원 절반정도를 제외한 대다수의 공무원이 간이완강기의 재사용 능력이 없는 것으로 분석되었다. 따라서 숙박시설의 각 실별로 추가로 설치해야 하는 피난 기구 중 간이완강기는 제외하고, 연속적으로 사용가능한 완강기만을 설치할 수 있도록 관련 법률을 재정비할 필요가 있다. 셋째, 완강기 최대부하 인지 능력은 소방공무원 직무별로 구조대원이 가장 높았으며, 소방행정요원이 가장 낮게 나타났다. 소방행정요원의 인지능력을 향상시키기 위해서는 소방학교에서 정기적으로 실시하는 지휘역량 교육 등 각종 집합교육에서 완강기에 대한 이론 및 실무교육을 강화할 필요가 있다. 마지막으로 실제 목격한 장소는 숙박시설이 가장 높게 나타나서 다른 시설보다 숙박시설 화재를 가상하여 완강기 체험교육을 실시하는 것이 교육효과가 높을 것으로 생각된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.118-120
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• 2005

Nowadays, economical and social environments are changing to the type of an advanced country for development of techniques in power industry. So most of workers are recently avoiding the 3D works and asking for safety of working environment, etc. in highly dangerous parts such as hot line working on distribution lines, especially. Therefore, most advanced countries are using the support-arm or robotic systems on distribution line works for securing the construction reliability, economical feasibility and protection of linemen from the electric shock and so forth. In special Japanese electric power companies are using the robotic system named manipulator. In Korea, a support-arm has been developed for safety and facility in live working on distribution lines but not widely supplied. In this paper we will introduce development cases of support arm and manipulator robot for live working on distribution lines.

• 한국환경보건학회지
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• 제34권1호
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• pp.27-33
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• 2008

In order to evaluate the magnetic field (MF) exposure level in residential areas near high voltage power lines, this research measured MF levels at 120 sites near high voltage transmission lines in the Busan region, Gwangju region, Daegu region and Changwon region from July to December, 2005, and compared and analyzed the efficiencies by measuring and applying the MF emission levels of underground cables and high voltage transmission lines. As a result of the investigation of the MF exposure level by the building usage, the average MF level of 17 locations at schools was $2.44{\pm}2.45mG;$ that of 10 locations at hospitals $6.21{\pm}12.39mG;$that of 76 locations at apartments $2.55{\pm}2.98mG;$ and that at kindergartens and infant houses $3.32{\pm}4.21mG$. MF exposure was analysed as a function of distance from the source and the MF levels directly below a source were $5.15{\pm}8.72mG$, those within 30 m were $3.10{\pm}3.32mG$, while those within 50 m were $2.45{\pm}2.38mG$, and within 100 m were $0.71{\pm}0.93mG$. In order to determine the difference of MF levels by the actual distance from high voltage transmission line within the same building, the evaluation of the floor position and the MF level has shown that the MF levels were highest in the order of roof, 4th floor, 3rd floor, 2nd floor and 1st floor. Comparison of MF emission intensity of underground cables and high voltage transmission lines, has shown that underground cables have an 86-94% of reduction ratio in MF compared to high voltage transmission lines, thus demonstrating higher efficiency.

• 한국압력기기공학회 논문집
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• 제6권2호
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• pp.54-60
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• 2010

Piping failures due to thermal fatigue have been widely reported in normally stagnant non-isolable reactor coolant branch lines. Since the thermal fatigue due to thermal stratification was not considered in the piping fatigue design in old NPPs, it is important to evaluate the effect of thermal stratification on the integrity of branch lines. In this study, geometrical screening criteria for Up-horizontal branch lines in MRP-132 were applied to SI(Safety Injection) lines of KSNP 2-loop and WH 3-loop. Some computational fluid dynamic(CFD) analyses on the Reactor Coolant System(RCS) branch lines were also performed to develop the regulatory guidelines for screening criteria. As a result of applying MRP-132 screening criteria, KSNP 2-loop and WH 3-loop SI lines are determined to need further detailed evaluation. Results of CFD analyses show that both valve isolation and amount of leakage through valve can be used as technical bases for the screening criteria on the thermal fatigue analysis.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.207-222
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• 2020

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

• Wind and Structures
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• 제29권5호
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• pp.299-312
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• 2019

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.

• 한국해양공학회지
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• 제26권4호
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• pp.77-85
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• 2012

A study was performed on the design of a mooring line to maintain the position of a floating WEC (wave energy conversion) system. The procedure to design a mooring line is set up and the safety of the designed mooring system is evaluated using commercial software, Orcaflex. The characteristics curve for one line is analyzed to determine the properties and pretension of a mooring line. While considering the ocean environmental condition and importance of a floating WEC system, a multi-line layout is determined. A 4-point mooring system with 4 lines shows the instability in the yaw motion of the floating WEC system under a designed ocean environmental condition. The redesigned 4-point mooring system with 8 lines is found to be safe on the condition of a harsh ocean environment. The floating WEC system with the redesigned mooring system also shows stable motion in surge and pitch under operating conditions. From a parametric study on the mooring line length, the extreme value of the mooring line tension is found to be very sensitive to the pretension and length of mooring line. The results of this study can contribute to the establishment of a design procedure for mooring lines.

• 한국안전학회지
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• 제36권5호
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• pp.10-17
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• 2021

The controversy over the risk of the human body being affected by electromagnetic fields emitted from 60 Hz power lines continues without end. There are currently no new studies or research progress being made in this direction that is notable, and the number of civil complaints is gradually increasing. The problem is that each study produces different results, among which the effect of exposure to magnetic fields on childhood leukemia is a major one. In Korea, an electrician who was maintaining a 22.9 kV power line died of leukemia, which has recently been recognized as an occupational disease. Methods to reduce magnetic fields from power lines include shielding with wire loops, incorporating split phases and compaction techniques, installing underground power lines, converting to high-voltage direct current (HVDC), and increasing the ground clearance of transmission towers. Depending on whether a separate power supply is needed or not, there are two types of wire loops: passive loop and active loop. Magnetic field reduction is currently done through underground power lines; however, the disadvantage of this process is high construction costs. Installing passive loops, with relatively low construction costs, leads to lower magnetic field reduction rates than installing underground cables and a weakness to not solving the landscape problem. This methodological study aims at designing methods and reducing the effects of 2-wire set loops-the simplest and most practical. Since the method proposed in this study has been designed after analyzing the distribution of complex electromagnetic fields near the expected loop installation location, a practical design can be implemented without the need for any difficult optimization programming.