• 한국안전학회지
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• 제20권2호
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• pp.61-66
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• 2005

This paper presents an human reliability assessment(HRA) for a installation task of the temporary power cable in construction fields. HRA is evolved to ensure that the workers could reliably perform critical tasks such as a process of the temporary power cable. Human errors are extremely commonplace, with almost everyone committing at least some errors every day. The considerable parts of electric shock accidents in the construction field are caused by a series of human errors. Therefore it is required to analyze the human errors contained in the task causing electric shock event, the event tree analysis(ETA) is adopted in this paper, and particularly human reliability was estimated for a installation task of the temporary power cables. It was assumed that the error probabilities of the human actions may be obtained using the technique for human error rate prediction(THERP). The results show that the predominant task on reliability in the cable installation tasks is check-out tasks and the probability causing electric shock by human errors was calculated as $1.0\times10^{-9}$.

• Progress in Superconductivity
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• 제5권2호
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• pp.89-93
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• 2004

We have studied alternating transport current losses in the vertically stacked high temperature superconducting tapes(HTS) using numerical techniques. In the case of stacked conductors, HTS tapes are exposed to self-field generated by transport current itself and also experienced external magnetic field around adjacent tapes. It is well known that magnetic interactions between neighbored tapes have significant effect on their properties of superconducting tapes such as current distribution, AC loss, and critical current. In this paper, we investigated the transport current losses in stacked conductors consisting of a few of the HTS tapes using numerical analysis. Current distributions are calculated in HTS tape cross-section taking account of magnetic field dependencies, which are represented superconducting nonlinear properties. Dissipated losses in tape and stacked conductors were integrated with current distribution and electric field intensity in the whole conductor region. Finally estimated results were discussed and verified through the analytical theory.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.1-2
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• 2009

The high critical current ($I_c$, A) of SmBCO coated conductor in a magnetic field, the high production rate and the high material yield are promising for applications. The inhomogeneity of Ie at the long length coated conduct is very important problem for electric application. So we researched the reason of inhomogeneity of $I_c$ at long length tape prepared by batch type co-evaporation system called by EDDC. The long length SmBCO coated conductors were developed on $LaMnO_3/IBAD-MgO/Y_2O_3/Al_2O_3$/Hastelloy C276 template. The distribution of $I_c$ are from 0 to 397 A/cm at 77 K and self field. We have studied the microstructures of these films by using SEM, EDS and X-ray diffraction. The XRD and composition by EDS results of SmBCO film reveals subtle difference. But, the microscopic observation by SEM show the microcrack at the sample with low $I_c$.

• Journal of Radiation Protection and Research
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• 제33권4호
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• pp.183-196
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• 2008

원전주변의 주민에 대한방사선량의 대부분을 음식물 섭취에 의한 내부피폭이 차지하고 있다. 그러나 우리나라 원전에 적용하고 있는 음식물 섭취 관련 인자는 1989년 한국원자력연구소가 고리원전 주변지역을 대상으로 수행한 현장조사 결과를 계속 적용하고 있어 최근의 식습관 변화를 적절히 반영하지 못하고 있다. 또한 우리나라는 미국 NRC (Nuclear Regulatory Commission) 에서 적용하고 있는 최대개인에 근거하여 음식물 섭취율을 결정하고 있다. 그러나 최근의 ICRP (International Commission on Radiological Protection) 의 권고 및 유럽의 관련 지침에서는 결정집단 또는 결정집단을 대표하는 개인에 대해 선량을 평가토록 권고하고 있다. 따라서 이러한 식습관의 변화추이나 피폭평가대상에 대한 국제적인 권고기준에 준하는 음식물 섭취율 설정방법에 대한연구가 필요하다. 보건복지가족부에서는 국민건강증진법에 의거 매 3년마다 전국 규모의 국민의 식품 및 영양섭취실태 조사를 실시하고 있다. 따라서 본 연구에서는 이러한 정부조사자료를 활용하여 주기적으로 음식물 섭취량 자료를 갱신할 수 있는 방안을 연구하였다. 보건복지가족부에서 $2001{\sim}2002$년에 수행한 국민영양조사원자료(raw data)를 분석하여 결정집단을 대표하는 개인의 음식물 섭취율을 결정하는데 이용할 수 있는 기초통계량을 제시하고, 또한 현재 국내 원전에서 적용하고 있는 최대개인의 음식물 섭취율을 재설정하였다.

• 스마트미디어저널
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• 제4권1호
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• pp.33-38
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• 2015

분 논문에서는 전위계 센서를 이용한 비접촉식 동작인식거리를 확장하기 위해 1K Hz 이하의 극저주파 EMI를 제거하는 기법과 제스처 동작 시작점 추출을 위한 PLN(Power Line Noice)을 이용하는 기법을 제시한다. 스마트기기 상에 장착된 전위계차 센서 주변에서 발생하는 극저주파대역의 전기장의 세기를 측정하여 효율적인 센서의 배치를 통해 EMI를 제거하는 동시에 60Hz 대역의 PLN 잡음은 오히려 동작 시작점 검출을 위하여 이용하는 기법을 제안한다. 이 후, 접지를 통해 스마트 기기 및 센서의 회로에서 발생하는 전원선 잡음을 제거하고, 스마트 TV와 센서의 사이를 차폐시킴으로써 스마트 기기에서 발생하는 전기적 잡음을 제거한다. 마지막으로 필터기법을 이용하여 남아있는 미세 잡음을 제거한다. 전위계차 센서를 스마트기기의 비접촉식 원격제어에 활용하기 위한 극저주파대역 EMI의 효과적인 제거 기법 및 성능을 분석하였으며, 또한 전위계차 센서의 비접촉식 응용에 난제중 하나인 동작시작점 검출을 위한 효과적인 방법을 제시하여 제스처 인식거리를 실제 응용가능한 3m 이상으로 확장할 수 있음을 보였다.

• 대한기계학회논문집B
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• 제35권11호
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• pp.1213-1217
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• 2011

의료용 자극기는 병원과 가정에서 환자의 통증 경감 및 재활 치료를 위해 사용되는 의료기기이다. 전기자극기의 자극 펄스가 심장에 유입되면 부정맥 및 심실세동 등의 심각한 부작용을 초래할 수 있다. 의료용 자극기에서 공급하는 자극 펄스의 전달 거리를 측정하고 심장이 전기 자극의 위험 범위 밖에 위치하도록 자극의 크기 및 자극 부위를 제한할 필요가 있다. 전기 자극기는 초당 60 회의 빈도로 0.001Joule 전기 펄스를 가하도록 설계되었다. 전기 자극기의 성능 및 인체에 미치는 영향을 측정하기 위해 생리 식염수를 이용한 생체 조직의 모델을 제작하였고, 이를 이용하여 거리에 따른 전기장의 감쇄 정도를 측정하였다. 본 연구에서 개발한 전기 자극기를 동물실험에 적용한 후 심장 주변에 전기자극을 가했을 때 심장에서 나타나는 위험요인을 관찰하고 직류전류가 흘렀을 때 심장에서 나타나는 현상과 비교하였다.

• 세라미스트
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• 제23권1호
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• pp.89-100
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• 2020

Abnormally large electromechanical strain properties have been reported in bismuth-based piezoelectric ceramics, which cast a promise for replacing the market-dominating PZT-based piezoelectric ceramics in actuator applications. In spite of these large strains in bismuth-based piezoelectric ceramics, there still remains a critical issue for its safe transfer to practical applications, representatively, a relatively high operating field required to obtain the large strain properties. To overcome the challenge, much attention has been paid to so-called 0-3(or 3-0) type ceramic/ceramic composite approach to better tailoring the strain properties of bismuth-based piezoelectric ceramics. The approach turns out to be highly effective, leading to a drastic decrease in the operating electric field for these materials. Besides, both extensive and intensive search for the related mechanism revealed that the reduction in the operating electric field is largely due to the contribution from polarization coupling or strain coupling model between two different ceramics. This article reviews the status of the art in the development of novel ceramic/ceramic composites to make large incipient piezostrains in bismuth-based lead-free piezoelectric ceramics practical.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권9호
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• pp.522-529
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• 2002

In this paper, computer simulations of the physical Phenomena occurring in the arc region before and after current zero were carried out to evaluate the thermal recovery characteristics of a Laval nozzle. A commercial CFD program "PHOENICS" is used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by the comparison with the test results presented by the research group of GE Co.(General Electric Company). In order to investigate the state of the arc region after current zero, the simulation was carried out with three steps. They are steady state arc simulation, transient arc simulation before current zero, and transient hot-gas flow simulation after current zero. The semi-experimental arc radiation model is adapted to consider the radiation energy transport and Prandtl's mixing length model is employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The post-arc current was calculated to evaluate the thermal recovery characteristics after current zero. Compared with the results obtained by GE Co., it has been found that the critical RRRV(ratio of rise of recovery voltage) will be determined previously by this study.his study.

• KEPCO Journal on Electric Power and Energy
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• 제7권1호
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• pp.129-135
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• 2021

Recently, additive manufacturing (AM) technology such as powder bed fusion (PBF) and directed energy deposition (DED) are actively attempted as consumers' needs for parts with complex shapes and expensive materials. In the present work, the effect of processing parameters on the mechanical properties of 316L stainless steel coupons fabricated by PBF and DED AM technology was investigated. Three major mechanical tests, including tension, impact, and fatigue, were performed on coupons extracted from the standard components at angles of 0, 45, 90 degrees for the build layers, and compared with those of investment casting and commercial wrought products. Austenitic 316L stainless steel additively manufactured have been well known to be generally stronger but highly vulnerable to impact and lack in elongation compared to casting and wrought materials. The process-induced pore density has been proved the most critical factor in determining the mechanical properties of AM-built metal parts. Therefore, it was strongly recommended to reduce those lack of fusion defects as much as possible by carefully control the energy density of the laser. For example, under the high energy density conditions, PBF-built parts showed 46% higher tensile strength but more than 75% lower impact strength than the wrought products. However, by optimizing the energy density of the laser of the metal AM system, it has been confirmed that it is possible to manufacture metal parts that can satisfy both strength and ductility, and thus it is expected to be actively applied in the field of electric power section soon.

• 한국정밀공학회지
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• 제32권8호
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• pp.755-760
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• 2015

For proper wound healing, dermal contraction and remodeling are critical; during the natural healing process, differentiated fibroblasts called "myofibroblasts" typically undertake these functions. For severe wounds, however, a critical mass of dermal matrix and fibroblasts are lost, making self-regeneration impossible. To overcome this impairment, synthetic wound patches with embedded functional cells can be used to promote healing. In this study, we developed a polydioxanone (PDO)-based cell-embedded sheet on which dermal fibroblasts were cultured and induced for differentiation into myofibroblasts, whereby the following combinatorial physicochemical stimuli were also applied: aligned topology, electric field (EF), and growth factor. The results show that both the aligned topology and EF synergistically enhanced the expression of alpha smooth-muscle actin (${\alpha}$-SMA), a key myofibroblast marker. Our proof-of-concept (POC) experiments demonstrated the potential applicability of a myofibroblast-embedded PDO sheet as a wound patch.