• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1803-1805
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• 2000

This paper analyzes the effects of Ge profiles shape of SiGe heterojunction bipolar transistors (HBT's) for high frequency application. Device simulations using ATLAS/BLAZE for the SiGe HBT with trapezoidal or triangular Ge profile are carried out to optimize the device performance. An HBT with 15% triangular Ge profile shows higher cut-off frequency and DC current gain than that with 19% trapezoidal Ge profile. The cut-off frequency and BC gain are increased from 42GHz to 84GHz and from 200 to 600, respectively.

• Journal of electromagnetic engineering and science
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• 제12권2호
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• pp.171-175
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• 2012

In this work, a new microstrip-to-substrate integrated waveguide (SIW) transition using the parallel half-mode substrate integrated waveguide (HMSIW) is proposed. The proposed transition consists of three sections : a microstrip, parallel HMSIWs, and an SIW. By inserting the parallel HMSIWs section between the microstrip section and the SIW section, the proposed transition can improve the return loss characteristics of the near cut-off frequency because the HMSIWs section has a lower cut-off frequency than the SIW section (8.6 GHz). The lower cut-off frequency is achieved through gradual electromagnetic field mode changes for a low reflection. The measured return loss is less than 20 dB in the of 9.1~16.28 GHz freqeuncy range for the back-to-back transition. The measured insertion loss is within 1.6 dB for the back-to-back transition. The proposed transition is expected to play an important role in wideband SIW circuits fed by a microstrip.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.5-6
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• 2014

According to 2013 fire statistical yearbook in the National Emergency Management Agency, the main cause of an electrical fire are classified to short circuit fault, overload fault, electric leakage, partial disconnection, and joint/contact badness. The occurrence factor of fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Devices(RCDs) of high sensitivity type used at single phase (220V) cut off earth leakage and overload but the RCDs can not cut off electric arc or spark to be a main cause of electrical fire. To be improved on such problem, this thesis is proposed to a auxiliary control device for RCD cut off electric arc or spark.

• 한국정밀공학회지
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• 제5권1호
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• pp.71-77
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• 1988

This study applies dynamic deformation analysis to the rake face stress distribution of cemented carbide cut-off tools by turning, using a finite element method. The results are following: 1. The dynamic loaded state of a cut-off tool was very changeable for the first 0.6 seconds. Reaching the normal state, it became in active. 2. Chipping was influnced not only by the magnitude of stress but also by the abrupt change of tensile and compressive stresses. 3. The distribution chat of principal stress by dynamic load and the direction of resultant vector were almost constant regardless of load time.

• 호남수학학술지
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• 제40권4호
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• pp.785-794
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• 2018

In [8] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities. They consider the Poisson equations with homogeneous Dirichlet boundary condition with one corner singularity at the origin, and compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution they could get an accurate solution just by adding the singular part. This approach uses the polar coordinate and the cut-off function to control the singularity and the boundary condition. In this paper we consider Poisson equations with multiple singular points, which involves different cut-off functions which might overlaps together and shows the way of cording in FreeFEM++ to control the singular functions and cut-off functions with numerical experiments.

• 전기학회논문지
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• 제68권4호
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• pp.593-597
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• 2019

We proposed a current Interruption type DC superconducting circuit breaker(I-DC SCB), a protection device that combines the current limiting technology of a superconductor with the cut-off technology of circuit breaker. Unlike existing protective devices, the current I-DC SCB is a device that combines two protection functions, notably improving failure probability and operational reliability. It is also applicable to all DC systems, such as HV, MV, and LVDC, due to the ease in capacity increase. The 100 kV I-DC SCB was designed after taking into account the actual power system conditions, followed by an analysis of the transient characteristics and the breaking range of the limiter. The results of the analysis showed that the I-DC SCB had a fault current limit of about 75% at the rated voltage, and completed the cut-off operation within about 20 ms.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1157-1166
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• 2021

In this study, a numerical sensitivity analysis was performed to determine the fire suppression time for a large number of water mist nozzles in a large fire compartment. Fire simulations were performed using FDS (Fire dynamics simulator) 6.5.2 under the same condition as the test scenario 5 of the International Maritime Organization (IMO) 1165 test protocol. The sensitivities of input parameters including cell size, extinguishing coefficient (EC), droplets per second (DPS), and peak heat release rate (HRR) of fuel were investigated in terms of the normalized HRR and temperature distribution in the compartment. A new method of determining the fire suppression time using FDS simulation was developed, based on the concept of the cut-off time by cut-off value (COV) of the heat release rate per unit volume (HRRPUV) and the cooling time by the HRR cooling time criteria value (CTCV). In addition, a method was developed to determine the average EC value for the simulation input, using the cooling time and cut-off time.

• Journal of Animal Science and Technology
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• 제49권2호
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• pp.203-212
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• 2007

돼지의 부분육의 중량과 수율의 개량을 위하여 생체에서 이를 측정할 수 있는 수단이 필요하다. 4개의 교잡 계통돈 돼지 432두에 대하여 시기별 생체 측정치와 도축자료를 조사하였다. 생체중 및 도체중 그리고 부분육의 중량은 도축일령에 의해 영향을 거의 모두 받고 있지만 수율에 있어서는 삼겹살과 목심에만 유의성있게 영향하는 것으로 나타났다. 부분육의 형질과 시기별 생체 측정치간의 상관 조사에서 대부분의 체측정치에서 검정 종료시의 측정치가 다른 시기의 측정치보다 상관이 높게 나타났고, 부분육 형질의 예측을 위한 회귀식에서도 검정 개시와 출하시의 체측정치 보다 검정 종료시 체측정치를 이용하였을 때 결정계수가 모든 부분육의 형질에서 높아 가장 정확하게 추정하였다. 부분육 형질을 평균 출하일령으로 보정한 뒤, 검정 종료시 체측정치의 3차 다항회귀 식에 의한 부분육 형질의 예측에서 중량과 수율의 결정계수가 각각 0.59~0.68과 0.33~0.43의 범위를 보여주어 이를 돼지의 부분육 형질의 개량을 위해 활용하면 국내 선호부위가 우수한 한국형 종돈의 생산이 기대된다.

• 한국식품과학회지
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• 제29권6호
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• pp.1316-1318
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• 1997

산 casein으로부터 FPLC를 이용하여 gel permeation column으로 ${\kappa}-Casein$을 분획한 다음, 이를 chymosin, pepsin, trypsin 으로 각각 처리하여 3% TCA에서 soluble한 부분을 증류수로 투석(MW cut-off 1kDa)시킨 후 ACE저해 효과를 측정한 결과, trypsin으로 분해 시킨 경우 ACE 저해율이 94.7%로 가장 높게 나타났으며, chymosin 가수분해물은 가장 낮았다. GMP를 투석막의 종류에 따라 투석 시킨 후 $IC_{50}$을 측정한 결과, MW cut-off 의 크기가 증가할수록 ACE저해효과는 감소하는 것으로 나타났으며, MW cut-off 2 kDa의 경우가 가장 높은 저해율을 보였고 MW cut-off 5kDa에서는 저해율이 가장 낮았다.

• 융합정보논문지
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• 제9권6호
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• pp.175-182
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• 2019

본 연구는 노인운전자용 자가 보고식 평가 SAFE-DR 개발 프로젝트의 일환으로 운전위험성 선별을 위한 기준점수를 확인하고 평가의 타당성을 검증하기 위해 수행되었다. Driver 65 Plus평가를 통해 노인운전자 132명을 58명의 위험성 운전자와 74명의 안전성 운전자로 구분하고, 이를 기준으로 SAFE-DR 평가의 위험성 예측 기준을 분석하였다. 또한 SAFE-DR 평가의 구성 타당도, 내용 타당도, 예측 타당도를 검증하였다. SAFE-DR 평가의 운전위험성 예측을 위한 기준점수는 74.5점으로 분석되었으며, 이 기준의 양성 예측도는 88.6%, 음성 예측도는 86.3%로 판별력은 훌륭한(excellent) 수준으로 확인되었다. 또한 집중타당성, 법칙타당성, 내용타당성이 적절한 것으로 판정되었다. 따라서 본 연구를 통해 SAFE-DR은 위험한 노인운전자를 선별하는 용도로 활용할 수 있는 적절한 평가임을 확인하였다.