• 지구물리
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• 제9권4호
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• pp.371-376
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• 2006

고해상도의 디지털 카메라는 근거리 수치사진측량에서 널리 유용하게 사용되고 있으며 점차 활용도가 증가하고 있다. 또한 사진측량 장비의 급속한 발전으로 정밀도가 많이 향상되었고 컴퓨터를 이용한 지형공간정보체계기술의 발달로 더욱 정밀한 3차원 지형의 재현과 면적 및 토공량 산정이 가능하게 되었다. 본 연구에서는 휴대가 간편하고 수치영상의 자체저장능력을 지닌 디지털 카메라를 이용하여 촬영조건의 다양한 변화에 따른 위치오차를 분석하였으며 광속조정을 통하여 높은 정확도의 화소 좌표를 획득하여 3차원 지형의 모델링을 위한 기초 자료로 사용할 수 있도록 하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.581-586
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• 2000

The equivalent source method is used to calculate the internal pressure field for an enclosure which can have arbitrary boundary conditions and may include internal objects which scatter the sound. Some of the equivalent positions are chosen to be the same as the first order images of the source inside the enclosure, some are positioned on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. The convergence of this method is checked by evaluating the velocity error at a larger number of monitoring positions. Example results are presented for various numbers of sources and evaluation points. The results showed that in general the more equivalent sources increased the accuracy of the sound field predictions but the accuracy is not too much sensitive to the numbers of evaluation points.

• 한국기계가공학회지
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• 제4권3호
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• pp.32-38
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• 2005

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

• 대한기계학회논문집B
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• 제26권3호
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• pp.482-490
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• 2002

This paper presents modelling and analyzing method of centrifugal chiller which has a rated capacity of 200 RT(703 kW) through on-site performance test. Field performance data of a chiller installed in a research building of KIST have been collected. Simple models were developed for predicting the heat exchanger and system performances by regression of chiller operation data during 5 days in August. The models proposed here account for the effect of variations of cooling capacity, temperatures and flew rates of secondary fluids. The proposed models can predict the actual performance data from June to September within $\pm$ 5% error. The COP of centrifugal chiller are estimated under the standard rating conditions and reduced mass flow rates of chilled and cooling water.

• 한국산학기술학회논문지
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• 제9권2호
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• pp.270-275
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• 2008

자동차용 직선 베벨기어는 대량으로 생산되고 있기 때문에 생산성 향상을 위해 기어가공용 전용기에서 직접 가공하던 것을 냉간 단조 제조방식으로 변경되어 생산되고 있다. 시행착오를 최소화하여 단조에 의한 정확한 최종 형상의 정밀 제품을 조기에 개발하고, 반복 재현성을 확보하는 방법으로 CAD/CAM 시스템의 도입이 필요하다. 본 연구에서는 CAD/CAM 시스템을 활용하여 크라운 치형을 갖는 직선 베벨기어를 모델링 한다. 이를 토대로 NC 데이터 생성과 검증을 통해 가공품을 사전에 예측을 한 후 물림시험의 결과를 통해 마스터 기어를 제작한다. 이러한 마스터기어를 통하여 금형제작이나 가공에 필요한 지그제작을 가능하게 한다.

• 한국도로학회논문집
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• 제19권2호
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• pp.35-44
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• 2017

PURPOSES: This study suggests a specific methodology for the prediction of road surface temperature using vehicular ambient temperature sensors. In addition, four kind of models is developed based on machine learning algorithms. METHODS : Thermal Mapping System is employed to collect road surface and vehicular ambient temperature data on the defined survey route in 2015 and 2016 year, respectively. For modelling, all types of collected temperature data should be classified into response and predictor before applying a machine learning tool such as MATLAB. In this study, collected road surface temperature are considered as response while vehicular ambient temperatures defied as predictor. Through data learning using machine learning tool, models were developed and finally compared predicted and actual temperature based on average absolute error. RESULTS : According to comparison results, model enables to estimate actual road surface temperature variation pattern along the roads very well. Model III is slightly better than the rest of models in terms of estimation performance. CONCLUSIONS : When correlation between response and predictor is high, when plenty of historical data exists, and when a lot of predictors are available, estimation performance of would be much better.

• Environmental Engineering Research
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• 제25권3호
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• pp.400-408
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• 2020

Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1032-1037
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• 2003

Although the holes on the shell case are very important fer the acoustic performance, it is difficult to solve the problem because the case includes thin bodies. Hence, in the past, only the method of trial and error, which depends on the engineer's intuition and experience, was available fur the design of holes. Many researchers have tried to solve the thin-body acoustic problems, since the conventional boundary element method (BEM ) using the Helmholtz integral equation fails to yield a reliable solution fer the numerical modelling of radiation anti scattering of sound from thin bodies. In the area of the analysis of thin-body acoustic problem, three approaches are generally used; the multi-domain BEM, the indirect variational BEM, and the normal derivative integral equation And there has been just a f9w study reported on the design optimization for the acoustic radiation problems by using only the conventional BEM. For the thin-body acoustics, however, no further study in the optimization fields has been reported. In this research, the normal derivative integral equation is adopted as an analysis formulation in the thin-body acoustics, and then used fur the optimization. The analytical approaches for the design of holes are proposed by using a topology optimization technique and a genetic algorithm. The proposed approaches are implemented and validated using numerical examples.

• 한국지능시스템학회논문지
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• 제18권6호
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• pp.731-736
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• 2008

본 논문에서는, 가상 모델을 이용한 움직임 추출 방법을 제안한다. 제안한 방법은 첫 번째, 기존에 제안된 방법으로써 RGB 칼라 모델을 이용하여 전경 영역에 나타나는 에러 값을 제거하고, HSI 칼라 모델을 이용하여 불필요한 정보 값을 제거한다. 두 번째, 사람 10명의 신체 구조비를 이용하여 가상 모델을 생성한다. 그 때, 생성된 가상 모델을 추출된 영역에 매칭시키고, 원 탐색 기법을 이용하여 전경영역의 실제 인간의 머리에 대한 얼굴 실루엣을 추출한다. 세 번째 추출된 정보들을 이용하여 mean-shift 알고리즘에 적용시켜 물체를 추적한다. 마지막으로, 본 논문에서 제안한 알고리즘은 복잡하고 다양한 환경에서 실험을 통해 그 응용 가능성을 증명한다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.377-382
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• 2009

modelling of the buck converter in photovoltaic power conditioning system is not a possibility of doing with input-output relationship from existing procedures. Because the input current and voltage of the buck converter in fluctuate at any time. The controller which design with the method which has like this error cannot have a good efficiency. In this paper, firstly, in order to design accurate controller of buck converter, new model is proposed. The modeling used a state-space averaging method and came to accomplish. Secondly, the process which design the controller is described. Finally, the simulation results are analyzed.