• 공업화학
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• 제29권6호
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• pp.789-798
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• 2018

고분자전해질 연료전지(PEMFC)의 성능을 예측할 수 있는 empirical equation의 역할이 중요하게 대두되고 있다. 본 연구에서는 polarization curve에서 activation loss, ohmic loss, mass transfer loss 영역을 분리하였고, 현재까지 개발된 model 중 Kim의 model과 Hao의 model을 선정하여 각 영역의 fitting을 시행하였다. 온도, 압력, 산소 농도 및 막 두께를 운전변수로 설정하여 조건 변화에 대한 각 loss의 변화를 비교하였다. 기존 model은 전반적으로 좋은 fitting 정확도를 보였지만, 분리된 loss 영역에서는 부정확한 fitting 결과를 보이기도 하였다. 연료전지 성능 예측의 정확도를 개선하기 위하여 converge coefficient를 도입한 새로운 model을 제안하였다. 본 연구에서 제안한 model을 연료전지 성능 예측에 적용한 경우에 신뢰도 평가에서 개선된 결과를 얻을 수 있었다.

• 한방재활의학과학회지
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• 제32권3호
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• pp.153-160
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• 2022

This retrospective study reports the effectiveness of Daoyin exercise therapy in a patient with lower back pain who suffered from idiopathic scoliosis. A patient was treated with Korean medicine containing Daoyin exercise therapy for 4 weeks. The patient was assessed for the numeral rating scale (NRS), Cobb's angle, correctability, and coronal balance. After treatment, the NRS of low back pain decreased from 9 to 1. The Cobb's angle of the thoracic curve decreased from 27.31° to 17.66°. The Cobb's angle of the lumbar curve decreased from 21.86° to 9.05°. Correctabililty was 35.34% in the thoracic curve and 58.60% in the lumbar curve. And coronal balance decreased from positive 32.80 mm to negative 3.20 mm. This study suggests that Daoyin exercise therapy could be effective therapeutic choice for lower back pain with idiopathic scoliosis.

• 호남수학학술지
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• 제39권4호
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• pp.637-647
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• 2017

Elastica is known as classical curve that is a solution of variational problem, which minimize a thin inextensible wire's bending energy. Studies on elastica has been conducted in Euclidean space firstly, then it has been extended to Riemannian manifold by giving different characterizations. In this paper, we focus on energy of the elastic curve in a Lie group. We attepmt to compute its energy by using geometric description of the curvature and the torsion of the trajectory of the elastic curve of the trajectory of the moving particle in the Lie group. Finally, we also investigate the relation between energy of the elastic curve and energy of the same curve in Frenet vector fields in the Lie group.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.291-294
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• 2005

In this study, we compared and analyzed the floor impact sound insulation performance produced by the rating methods. The rating methods are using reversed A-weighting curve, A-weighted sound pressure levels and arithmetic average. On-site floor impact sound pressure levels of living room and room are measured. The results of this study are 1)the rating using reversed A-weighting curve for heavy-weight impact sound's standard deviation is lower than that of light-weight impact sound, 2)the number of rating using A-weighted sound pressure levels and arithmetic average is larger than that of using reversed A-weighting curve, and 3)the number of rating using reversed A-weighting curve mainly depends on impact sound pressure level of 63Hz in heavy-weight impact sound.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1613-1616
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• 2005

In this paper, we developed an algorithm of generating cam contour curve for hinge mechanism of folder-type mobile phone. The main feature of this hinge mechanism is that we can operate uniform torque to open or close the mobile phone. We divided the opening or closing intervals of the cam into finite sub-intervals, and then we determined the cam contour curve of each sub-interval as a parabolic curve. Finally, these finite parabolic curves form the total cam contour. We can design single cam, which composed moving cam with contour curve and fixed cam that plays only roller, and twin cam with contour curve that is made up the pair of two cams symmetrically.

• 전기학회논문지
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• 제61권4호
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• pp.534-541
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• 2012

This paper tries to elicit an optimal generation mix of Korea. Two approaches, using the screening curve method and taking advantage of a generation expansion planning tool, WASP-IV, are applied in getting the mix. The data used in this study is based on the 5th basic plan for long-term electricity supply and demand. The Load Duration Curve, that is needed for applying Screening Curve Method(SCM), is made based on the load profile in 2010. In our using SCM, the nuclear plant's operation characteristic, carbon emission cost and spinning reserve are considered. In using WASP-IV to get the adequate generation mix, the base and target demand forecasts in the 5th basic plan are used and the carbon emission cost is also considered. In this paper, It introduces the domestic adequacy generation mix in 2024 though SCM and WASP-IV.

• 전기학회논문지
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• 제57권9호
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• pp.1500-1506
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• 2008

In this paper, we proposed new reliability characteristic curve, which-can clearly show reliability property of transmission and substation system considering uncertainty such as frequency and duration of device fault. It express the relationship of duration of load curtailments, demand not supplied, and energy not served as “ y = $ax^{-1}$ " curve. and we proposed the method, which can objectively assess reliability of transmission and substation system using proposed characteristic curve as new reliability index. In this method, we used energy index of reliability(EIR) as a criterion of assessment. Finally, we performed a variety of case study for KEPCO system in order to verify usefulness of proposed method.

• 응용통계연구
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• 제7권2호
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• pp.249-261
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• 1994

본 연구의 목적은 한국인구의 연도별 추정과 그 장래인구의 예측을 위한 단순 Logistic Curve의 모수(母數)들을 추정하는데 있다. 즉 1949년부터 1990년에 이르는 9회에 걸친 인구 Census 자료를 토대로 하고, 3-군법(3-群法)을 적용하여 모수들을 추정하므로서 연도별 총인구들의 곡선추계를 위한 Logistic Curve를 얻었다. 아울러 이 곡선에 의하여 1950년부터 1990년까지의 Census와 Census 사이의 총인구를 연도별로 추정하였으며, 다른 한편 1991년부터 2010년에 이르기까지 장래인구를 예측하였다. 뿐만 아니라 최근 한국인구 성장의 상한점근치(Upper Asymptote)로 58,616천명을 제시할 수 있었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권4호
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• pp.205-211
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• 2003

In this paper we propose a disturbance design method to test a system's stability. It is shown that the time maximum disturbance is represented in bang-bang and state feedback form. To maximize the time severity index, the value of disturbance is determined by the associated switch curve. The original switch curve is vulnerable to model uncertainties and takes much calculation time. We propose an improved method to approximate the original switch curve. This reduces the computational time and implements sufficiently to test the stable system. Simulation results show how the approximate switch curve can be used to stress a system by driving it to oscillation along the maximum limit cycle.

• 농촌지도와개발
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• 제17권2호
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• pp.305-326
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• 2010

This study aimed to investigate couple relationship and related variables of women immigrants. Especially, the study focused on curve term between couple relationship and related variables. The data were collected from a sample of 346 women immigrants living in S city, Chungnam province. First, the study indicated that there was some curve relationship between couple satisfaction and period of residence in Korea. Namely, the couple satisfaction of women immigrants was likely to decrease at the early period of residence, but the longer the period of residence was, the higher the couple satisfaction was. Second, the result revealed that there was no significant relationship between couple satisfaction and level of Korean proficiency. Third, there was some curve relationship between couple satisfaction and satisfaction of life. The couple satisfaction was likely to increase in a shape of curve according to the increase of life satisfaction.