• 한국추진공학회지
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• 제22권6호
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• pp.19-27
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• 2018

본 논문에서는 E-D 노즐 공압 실험 연구의 선행 연구로써, 노즐 압력비에 따라 변화하는 E-D 노즐특성 파악을 위한 해석적 연구가 수행되었다. 설계 변수 중, 핀틀 변곡 각도를 하나의 변수로 하여 서로 다른 세 가지 수치해석 모델을 설계하였다. 노즐 압력비가 낮을 때는 E-D 노즐 내부로 외부 대기가 유입되어 개방 유동장이 형성되었다. 노즐 압력비가 높아짐에 따라 노즐 내부에 재순환 영역이 고립되는 폐쇄 유동장으로 유동 천이가 발생함을 확인하였다. 또한, 전체 노즐 압력비 구간에서 핀틀 변곡 각도가 높은 해석 모델에서 가장 높은 추력 계수가 도출되었다.

• The Korean Journal of Physiology
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• 제11권2호
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• pp.1-7
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• 1977

The activity of the $Ca^{++}$ activated adenosinetriphosphatase (Ca-ATPase) of actomyosin systeme of rabbit and frog skeletal muscle has been studied at varying pH and temperature. The PH optima of the Ca-ATPase activity of the rabbit actomyosin was rather broad. Over the temperature range of $16-36^{\circ}C$ activity of the enzyme was not appreciably changed between pH 6.4-8.5; below and above which it rapidly reduced. The pH at the inflection point of the enzyme activity increased as temperature decreased, showing the ${\bigtriangleup}pH\;inflection/{\bigtriangleup}T$ of approximately $-0.018\;unit/^{\circ}C$. Consequently, $(OH^-)/(H^+)$ ratio at the inflection point was constant regardless of assay temperature. In the frog actomyosin systems the Ca-ATPase activity was not apparently altered between PH 6.4-7.0 when the incubation temperature was $15{\sim}30^{\circ}C$. Outside of this range of pH, however, the enzyme activity was dramatically decreased. The pH of the inflection point changed inversely with temperature. ${\bigtriangleup}pH\;inflection/{\bigtriangleup}T$ at the acidic side was approximately $-0.018\;unit/^{\circ}C$, whereas that at the alkaline side it was about $-0.037\;unit/^{\circ}C$. The Arrhenius Plot on the Ca-ATPase activity at constant $(OH^-)/(H^+)$ ratio of 1.0 was not linear, but showed break at arround $20^{\circ}C$ for both rabbit and frog actomyosin Preparations. From these results it was speculated that pH dependence of Ca-ATPase activity of rabbit actomyosin systems might reflect titrations of histidine-imidazole and -SH groups, and that of the frog actomyosin represents titrations of histidine-imidazole and lysyllysine ${\alpha}-NH_2$ groups.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권4호
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• pp.300-304
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• 2015

A low bit rate speech coder based on the non-uniform sampling technique is proposed. The non-uniform sampling technique is based on the detection of inflection points (IP). A speech block is processed by the IP detector, and the detected IP pattern is compared with entries of the IP database. The address of the closest member of the database is transmitted with the energy of the speech block. In the receiver, the decoder reconstructs the speech block using the received address and the energy information of the block. As results, the coder shows fixed data rate contrary to the existing speech coders based on the non-uniform sampling. Through computer simulation, the usefulness of the proposed technique is shown. The SNR performance of the proposed method is approximately 5.27 dB with the data rate of 1.5 kbps.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제16권4호
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• pp.276-280
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• 2016

A fixed rate speech coder based on the filter bank and the non-uniform sampling technique is proposed. The non-uniform sampling is achieved by the detection of inflection points (IPs). A speech block is band passed by the filter bank, and the subband signals are processed by the IP detector, and the detected IP patterns are compared with entries of the IP database. For each subband signal, the address of the closest member of the database and the energy of the IP pattern are transmitted through channel. In the receiver, the decoder recovers the subband signals using the received addresses and the energy information, and reconstructs the speech via the filter bank summation. As results, the coder shows fixed data rate contrary to the existing speech coders based on the non-uniform sampling. Through computer simulation, the usefulness of the proposed technique is confirmed. The signal-to-noise ratio (SNR) performance of the proposed method is comparable to that of the uniform sampled pulse code modulation (PCM) below 20 kbps data rate.

• 한국해양공학회지
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• 제22권5호
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• pp.39-43
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• 2008

For a partially filled and deeply submersed membrane container, an analytic solution for similarity shape was studied. The static shape of a membrane container can be expressed as a set of nonlinear ordinary differential equations. These equations are combined into an integrable equation. The solution of the equation is derived in terms of elliptic integrals, the arguments of which contain an unknown at the point of inflection. The point of inflection is determined by using the boundary condition at a separating point. Some characteristic values of the similarity shape were evaluated and the shapes are illustrated.

• 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.

• 음성과학
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• 제3권
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• pp.156-166
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• 1998

In this paper, I would like to propose a dividing method by estimating the inflection points and the average magnitude energy in speech signals. The method proposed in this paper gave not only a satisfactory solution for the problems on dividing method by zero-crossing rate, but could estimate the feature of the transient period after dividing the starting point and transient period in speech signals before steady state. In the results of the experiment carried out with monosyllabic speech, it was found that even through speech samples indicated in D.C. level, the staring and ending point of the speech signals were exactly divided by the method. In addition to the results, I could compare with the features, such as the length of transient period, the short term energy, the frequency characteristics, in each speech signal.

• 한국해양공학회지
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• 제21권1호
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• pp.45-50
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• 2007

For a long partially-filled membrane container on an incline, the analytic solution of the similarity shape is studied. The nonlinear equation is solved and its solution is expressed as elliptic integrals, which include an unknown at the point of inflection. The point of inflection is determined by using the boundary condition at the upper separating point. Some characteristic values of the universal shape are evaluated, as the functions of inclination angle and shapes are illustrated for some cases.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.85-92
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• 2003

When a current transformer (CT) is saturated, the wave-shape of the secondary current is distorted and contains points of inflection, which correspond to the start or end of each saturation period. Discontinuity in the first-difference function of the current arises at points of inflection, where the second and third differences convert into pulses that can be used to detect saturation. This paper describes the design and evaluation of a CT saturation detection technique using the third-difference function and includes the countermeasure for a spike signal. Test results clearly demonstrate that the algorithm successfully detects the start and end of each saturation period irrespective of the remanent flux and magnetization inductance in the saturated region. This paper concludes by describing the results of hardware implementation of the algorithm using a DSP.

• 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.