• 센서학회지
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• 제21권6호
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• pp.434-439
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• 2012

In this study, the oil degradation measuring for integrated sensor of drain valve was fabricated. A sensor used in the experiments was integrated with drain valves and installed in oil pan without requiring additional space. As a result of the experiments, the capacitances changed with two inflection points in accordance with an after in mileage. The first inflection point indicated the exhaustion of oil additives, and after the second inflection point, the oil degradation was completed, which increased the viscosity and disabled the functions of oil. Thus, this section was determined as the time of oil exchange.

• International Journal of Internet, Broadcasting and Communication
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• 제15권2호
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• pp.202-209
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• 2023

This study aims to analyze the correlation between semiconductor innovation and market dominance in the mobility electric vehicle industry. To this end, the study presentsstrategiesthat provide low-price competitiveness along with high-value creation in the electric vehicle and semiconductor markets. The first change in the era of high interest rates is to overcome the crisis of survival for value. Furthermore, the study acknowledges the ongoing second wave of change as the digital technology's value continues to rise, and companies experience decreased productivity due to rising ESG labor costs. The study analyzed price competitiveness in the context of the increased adoption of electric vehicles and the integration of semiconductor prices, proving that Tesla and Samsung Semiconductor have developed technology to dominate the market, with appropriate low-cost strategies applied as the value of innovation declines.

• 대한전기학회논문지:전력기술부문A
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• 제52권12호
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• pp.691-697
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• 2003

This paper proposes a current differential relay for transformer protection that operates in accordance with a blocking method based on the difference-function of a differential current. For magnetic inrush and over-excitation, discontinuities in the first-difference function of the differential current arise at the points of inflection, which correspond to the start and end of each saturation period of the core. These discontinuities are converted into the pulses in the second- and third-difference functions of the differential current. The magnitudes of the pulses are large enough to detect saturation of the core. A blocking signal is issued if the magnitude of the third-difference function exceeds the threshold and is maintained for three quarters of a cycle. The performance of the relay is assessed under various conditions with magnetic inrush, internal faults and external faults. The proposed blocking method can improve significantly the operating time of a relay and achieve high sensitivity of a relay.

• 한국의류산업학회지
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• 제13권5호
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• pp.661-671
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• 2011

This study was designed to produce rounded belt pattern and tight-skirt pattern drafting method using 3D body scan data. Subjects were thirty women in their early twenties. In order to figure out the optimum cutting points, namely, where darts are made, using CAD program, curve ratio inflection points on the horizontal curve of waist, abdomen, and hip to find 1 point in the front, two points in the back part. The average length from center front point to maximum curve ratio was 7.7 cm(46.3%) on the waist curve; 7.9 cm(39.4%) on the abdomen curve. And the average length from center back point to maximum curve ratio point was 6.9 cm(39.0%) for first dart and 11.2 cm(63.3%) for second dart on the waist curve; 8.9 cm(35.8%) for first dart and 15.7 cm(63.3%) for second dart on the hip curve respectively. The cutting lines from were made up by connecting curve inflection points. After divided using cutting lines, each patch was flattened onto the plane and all the technical design factors related with patternmaking were measured, such as dart amount, lifting amount of side waist point, etc. Based on the results of correlation analysis among these factors, regression analysis was done to produce equations to estimate the variables necessary to draw up pattern draft method; F1=F8+1.1, $F4=2.5{\times}F2+0.9$, $F5=0.9{\times}F4+1.0$, $F6=0.3{\times}F4+0.4$, $B1=0.9{\times}B8+2.3$, $B4=2.1{\times}B2+1.3$, $B5=0.9{\times}B4+3.5$, and $B6=0.3{\times}B4+0.4$.

• 한국연소학회지
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• 제2권1호
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• pp.9-16
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• 1997

This paper investigates the linear stability of wakes with special emphasis on the difference of velocity and density. Velocity and density profiles for laminar flows have gaussian profiles. Incompressible wakes have two generalized inflection points and two unstable modes-sinuous and varicose modes. Sinuous modes are more unstable than varicose modes irrespective of density variation, which shows wakes will be destabilized by sinuous modes. Large velocity difference and density difference leads to more unstable wakes due to large momentum difference.

• 한국의류산업학회지
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• 제12권4호
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• pp.467-476
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• 2010

The purpose of this study was to develop a plausible methodology based on experimental data how to set up darts and split lines on 3D parametric body dressed with tight-fit garment. The results were as following: Through the process of making convex hull, the concave parts were straightened to make a convex hull, especially in the center part of bust, under breast part and scapular part. To figure out the optimum positions of darts and split lines, the inflection points of curve ratio were searched along the horizontal polylines of waist and bust. This procedures produced reliable results with low deviation. Using Rapidform, CATIA and Unigraphics, six patches of bodice patterns were drawn and aligned. Paired t-test results showed the outline and area between 3D surface and 2D were not significantly different, meaning this method could be adaptable when flattening 3D surfaces. The amount of waist dart measured on the pattern showed that the highest portion was allocated on 2nd dart(back), followed by 1st dart(back), 1st dart(front), 2nd dart(front)/side dart, and center back dart. A series of findings suggested that curve ration inflection point could be used as a guide to set up darts and split line on 3D parametric model with low deviation.

• 한국정보통신학회논문지
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• 제13권10호
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• pp.2205-2210
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• 2009

본 논문에서 제안하는 잡음제거 방법은 hard 임계치 방법의 문제점을 개선한 제로점의 탄젠트 곡선 보간에 의한 잡음제거 기술이다. 자연계에서 관측되는 대기 전기변동량과 같은 신호의 시간적 변동량이나 가상현실을 이용하여 추출한사람의 빠른 움직임의 동작 곡선 등은 실제로 복잡하다. 따라서 이러한 신호의 관측파형에 대하여 변곡점에 대한 특징을 정확히 결정하는 것이 매우 중요하다. 특히 자연계의 측정 신호는 잡음이 포함되어 있어서 잡음을 제거하고 특징을 추출하는 것이 필요하다. 본 논문에서 제안한 새로운 방식에 의하여 잡음을 제거하고 변곡점을 추출하며 종래의 방식인 hard 임계치에 비하여 잡음지수가 5인 경우의 noise II 변곡점 신호에 대하여 SNR이 3.4dB 개선된 결과를 얻을 수 있음을 보였다.

• 전기전자학회논문지
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• 제24권4호
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• pp.1081-1085
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• 2020

변곡점 추출방법을 활용하여 AM-FM신호의 순간주파수를 추정하는 방법을 제안한다. 제안된 방법은 AM-FM신호의 국부적인 최대값/최소값을 변곡점 추출법을 활용하여 검출하며, 검출된 인접한 최대값/최소값 사이의 시간 간격을 계산하여 FM성분의 순간주파수를 추정한다. AM성분의 경우, 검출된 최소값/최대값의 포락선을 먼저 구하고 포락선의 최고값 간의 시간을 계산하여 순간주파수를 추정한다. 컴퓨터 모의실험으로 FM성분의 주파수가 고정된 경우와 변화하는 경우에 제안된 방법의 유용성을 검증한다. FM성분의 주파수가 일정한 AM-FM신호의 경우, 제안된 방법은 두 주파수 성분을 적절하게 추정한다. FM성분의 주파수가 변화하는 AM-FM신호의 경우, AM성분의 순간주파수는 적절히 추정되었으나 FM성분의 순간 주파수는 이론적인 주파수에서 편이되는 현상을 보인다. 이는 국소적인 최고점/최대점 검출로 표본수가 적어지는 효과에 따른 것으로, 저역통과 필터와 같은 후처리로 개선될 수 있다.

• 한국강구조학회 논문집
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• 제13권2호
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• pp.115-122
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• 2001

오늘날 컴퓨터가 복잡한 해석을 수행하는 도구로 이용되더라도 해석의 결과값에 대한 적합성을 평가하기 위해서는 공학적 판단이 필요하다. 근사해석법은 이러한 결과값을 검토하기 위한 편리한 도구가 될 수 있으며 골조의 응력분포 그리고 부재 사이즈의 직하중 및 수평하중을 받는 강접골조를 근사해석하기 위한 방법을 제시하는 것이며 본 연구에서 제안한 방법의 유효성을 검증하기 위해서 기존의 방법과 비교하였고 구조물 거동의 예측에 있어서 향상된 결과를 보여주었다.

• 대한기계학회논문집B
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• 제37권8호
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• pp.743-752
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• 2013

본 논문은 대형 상용기관을 모사한 정적연소실에서 매립지 가스의 연소 특성에 대한 복수의 논문 중 두 번째로, 연소압력 측정을 기반으로 연소과정을 해석하였다. 해석 결과 연소에 유리한 조건일수록 두 개의 압력 정점이 존재하며, 이는 연소에 의한 열발생과 열전달에 의한 냉각효과의 상호 작용이며 두 정점의 크기는 미연가스 분율에 따라 달라진다. 또한 연소과정 중 열발생에는 4개의 주요 변곡점이 발생하고, 이는 점화위치로부터 화염전파에 따른 전열 면적 변화과정이 주원인이며 연소에 불리한 조건일수록 변곡점은 증가하고 열발생은 복잡한 형태를 지니는데, 이는 연소기간 연장이 주원인이다. 결론적으로 점화위치와 관련된 화염전파 과정 및 전열 면적의 변화과정 그리고 대형 연소실에 의한 연소기간 연장의 효과가 상호 복잡하게 작용하면서 매우 특이한 형태의 열발생 곡선이 생성된다.