• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.489-492
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• 2007

Understanding the thermohydraulic processes in the aquifer is necessary for a proper design of the aquifer thermal energy utilization system under given conditions. Experimental and numerical test were accomplished to evaluate the relationship between the geothermal heat exchanger operation and hydrogeological conditions in the open-loop geothermal system. Sand tank experiments were designed to investigate the open-loop geothermal system. Water injection and extract ion system as open-loop borehole heat exchanger was applied to observe the temperature changes in time at injection well, extraction well and ambient groundwater. The thermohydraulic transfer for heat storage was simulated using FEFLOW for two cases of extraction and injection phase operation in sand tank model. As one case, the movement of the thermal plume was simulated with variable locations of injection and extraction well. As another case, the simulation was performed with fixed location of injection and extraction well. The simulation and experimental results showed that the temperature distribution depends highly on the injected water temperature and the length of injection time and the groundwater flow and pumping rate sensitively affect the heat transfer.

• 연구논문집
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• 통권30호
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• pp.147-157
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• 2000

The filtered vacuum arc source (FVAS), which is adopted by magnetic filtering methode to remove the macro-particle in vacuum arc plasma, was composed of a torus structure with bending angle of 60 degree. The radius of torus was 266 mm, the radius of plasma duct was 80 mm and the total length was 600 mm. The magnet parts were consisted of one permanent magnet, one magnetic yoke and five solenoid magnets. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The baffles inside plasma duct were installed in order to prevent the recoil effect of macro-particles. Graphite was used as the cathode material to coat the amorphic diamond film and its diameter was 80 mm. The amorphic diamond film attracts much attention due to its excellent mechanical, optical and tribological properties suitable for wide range of applications. The effects of solenoid magnet in plasma extraction were studied by computer simulation and experiment using Taguchi's method. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with low value of the source magnet current and high value of the filtering magnet current. Optimum deposition condition was obtained when the currents of arc discharge, source, extraction, bending, deflection and outlet magnet were 30 A, 1 A, 3 A, 5 A, and 5 A, respectively.

• 대한치과교정학회지
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• 제27권4호
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• pp.661-668
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• 1997

치열의 crowding을 해소하는 방법에는 크게 발치, 비발치로 크게 나눌 수 있다. 발치로 교정하는 경우 주로 고려되는 발치대상 치아는 제1, 2 소구치이며 그 다음이 제2 대구치, 하악전치, 제1대구치등 이다. 하악전치의 발치는 소구치 발치가 여의치 않을 때, 선택적으로 사용될 수 있다. case를 잘 선택한다면, 치료시간도 줄일 수 있고, 간편하게, 심미적 및 기능적으로도 좋은 효과를 얻을 수 있다. 아직 이에 대한 국내 연구와 보고가 활발하지 않아 소개하고자 한다.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.47-52
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• 2019

Micro-LEDs show lower efficiencies compared to general LEDs having large areas. Simulations were carried out using ray-tracing software to investigate the change in light extraction efficiency and light distribution according to chip-size of blue flip-chip micro-LEDs (FC ${\mu}-LEDs$). After fixing the height of the square FC ${\mu}-LED$ chip at $158{\mu}m$, the length of one side was varied, with dimensions of 2, 5, 10, 30, 50, 100, 300, and $500{\mu}m$. The highest light-extraction efficiency was obtained at $10{\mu}m$, beyond which the efficiency decreased as the chip-size increased. The chip size-dependence of the FC ${\mu}-LEDs$ both without the patterned sapphire substrate, as well as vertical FC ${\mu}-LEDs$, were analyzed.

• 한국음향학회지
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• 제13권4호
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• pp.32-39
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• 1994

한국어 음성인식 시스템을 구현하기 위한 기초 연구로서 한국어 전음소를 대상으로 1) 각 음소의 특성을 가장 잘 나타내는 최적의 위치, 2) 최고의 인식률을 얻기 위한 적당한 지속시간길이를 찾기위해서 음소인식을 수행하였다. 인식실험을 위해 특징파라메터로 21차원 켑스트럼계수를 이용하여 베이즈 결정법칙으로서 세화자에 대한 종속인식실험을 행하였다. 인식실험결과 최고의 인식률을 보이는 최적의 특징추출의 위치는 모음에서는 10~50ms, 마찰음및 파찰음은 40~100ms, 비음, 유음은 10~50ms, 그리고 파열음은 10~50ms임을 알 수 있었다. 또, 35 전음소를 대상으로한 인식에 있어서는 최고의 인식률을 얻기위한 지속시간 정 보의 길이는 60~70ms정도가 충분함을 알 수 있었다.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1135-1148
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• 2017

Speech recognition is one of the fascinating fields in the area of Computer science. Accuracy of speech recognition system may reduce due to the presence of noise present in speech signal. Therefore noise removal is an essential step in Automatic Speech Recognition (ASR) system and this paper proposes a new technique called combined thresholding for noise removal. Feature extraction is process of converting acoustic signal into most valuable set of parameters. This paper also concentrates on improving Mel Frequency Cepstral Coefficients (MFCC) features by introducing Discrete Wavelet Packet Transform (DWPT) in the place of Discrete Fourier Transformation (DFT) block to provide an efficient signal analysis. The feature vector is varied in size, for choosing the correct length of feature vector Self Organizing Map (SOM) is used. As a single classifier does not provide enough accuracy, so this research proposes an Ensemble Support Vector Machine (ESVM) classifier where the fixed length feature vector from SOM is given as input, termed as ESVM_SOM. The experimental results showed that the proposed methods provide better results than the existing methods.

• 한국산림과학회지
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• 제101권3호
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• pp.344-355
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• 2012

임목수확작업시스템 구축과 효율적인 임목수확작업 기술을 보급하기 위해 타워야더 및 스윙야더 등에 의한 전목집재작업시스템과 굴삭기 그래플 등에 의한 단목집재작업시스템의 작업시간 및 공정을 분석하였다. 전체 조사작업시간을 기준으로 분석한 1 cycle당 작업시간은 전목집재작업시스템에서 체인톱에 의한 벌목 46.6초/cycle, 타워야더에 의한 집재 480.6초/cycle, 스윙야더에 의한 집재 287.4초/cycle, 체인톱에 의한 조재 155.14초/cycle로 나타났다. 또 한 단목집재작업시스템에서는 체인톱에 의한 벌목 및 조재 225.65초/cycle, 굴삭기 그래플에 의한 단목집재 4,972초/cycle, 지엽집재 3,143초/cycle로 나타났으며, 바퀴식 미니포워더에 의한 소운재 4,688초/cycle, 굴삭기 그래플 및 소형운재차에 의한 소운재 2,118초/cycle로 나타났다. 전목집재작업시스템의 작업공정에서 체인톱에 의한 평균 벌목공정이 $57.89m^3$/일, 타워야더에 의한 평균 집재공정이 $20.3m^3$/일, 스윙야더에 의한 평균 집재공정이 $31.55m^3$/일, 체인톱에 의한 평균 조재공정이 $20.3m^3$/일로 나타났다. 또한, 단목집재작업시스템의 작업공정에서 체인톱에 의한 평균 벌목 및 조재공정이 $11.96m^3$/일, 굴삭기 그래플에 의한 평균 단목집재공정이 $34.75m^3$/일, 굴삭기 그래플에 의한 평균지엽수집공정이 $37.66m^3$/일, 굴삭기 그래플에 의한 평균 작업로의 개설공정이 73.8 m/일로 나타났으며, 바퀴식 미니포워더와 굴삭기 그래플 및 소형 운재차에 의한 평균 소운재 작업공정이 각각 $15.73m^3$/일과 $65.03m^3$/일로 나타났다.

• 한국해양공학회지
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• 제35권4호
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• pp.296-304
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• 2021

Research on the development of marine renewable energy is actively in progress. Various studies are being conducted on the development of wave energy converters. In this study, a numerical analysis of wave-energy extraction performance was performed according to the body shape and scale of the sloped oscillating water column (OWC) wave energy converter (WEC), which can be connected with the breakwater. The sloped OWC WEC was modeled in the time domain using a two-dimensional fully nonlinear numerical wave tank. The nonlinear free surface condition in the chamber was derived to represent the pneumatic pressure owing to the wave column motion and viscous energy loss at the chamber entrance. The free surface elevations in the sloped chamber were calculated at various incident wave periods. For verification, the results were compared with the 1:20 scaled model test. The maximum wave energy extraction was estimated with a pneumatic damping coefficient. To calculate the energy extraction of the actual size WEC, OWC models approximately 20 times larger than the scale model were calculated, and the viscous damping coefficient according to each size was predicted and applied. It was verified that the energy, owing to the airflow in the chamber, increased as the incident wave period increased, and the maximum efficiency of energy extraction was approximately 40% of the incident wave energy. Under the given incident wave conditions, the maximum extractable wave power at a chamber length of 5 m and a skirt draft of 2 m was approximately 4.59 kW/m.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.505-508
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• 2004

Gate length dependent data of intrinsic MOSFET equivalent circuit parameters are extracted using a direct extraction technique based on simple 2-port parameter equations. The relatively scalable data with respect to gate length are obtained. These data are verified to be acrurate by observing good correspondence between modeled and measured S-parameters up to 30GHz. These data will be helpful to construct RF scalable MOSFET model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.187-189
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• 2004

This paper presents the system widely used for extraction of human body recognition system in the field of bio-metric identification. The Human body recognition system is used in many fields. This biological is appled to the human recognition in banking and the access control with security. The important algorithm of the identification software usese hand lines and hand shape geometry. We used the simple algorithm and recognizing the person by their hand image from the input camera. The geometrical characteristics in hand shape such as length of finger to whole hand length thickness of finger to length, etc are used.