• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1241-1246
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• 2005

본 장은 100MHz 수준의 고속 신호 샘플링을 위해 글리치 최소화 기법을 적용한 8비트 100MHz CMOS D/A 변환기 (Digital - to - Analog Converter : DAC) 회로를 제안한다. 제안하는 DAC는 0.35um Hynix CMOS 공정을 사용하여 설계 및 레이아웃을 하였으며, 응용되는 시스템의 속도, 해상도 및 면적 등의 사양을 고려하여 전류 모드 구조로 적용되었다. D/A 변환기의 선형 특성은 원래의 Spec. 과 유사하였으며, ${\pm}0.09LSB$ 정도의 DNL과 INL오차가 측정되었다. 제작된 칩 테스트 결과에 대한 오동작의 원인을 분석하였으며, 이를 통하여 칩 테스트를 위한 고려사항 등을 제안하였다.

• 산업경영시스템학회지
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• 제28권2호
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• pp.75-80
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• 2005

As a result of globalization process and TBT agreement, KS is also being revised, reestablished and some are abolished according to international standards such as ISO, IEC, etc. Conventional KS sampling inspection standards contained many different procedures from ISO, but recently, to match with international standards, all the rest of the standards except KS A 3102, 3104, 3151 were abolished, and the even the ones being in use still are also scheduled and be revised. Especially, KS A 3101, KS A 3105, KS A 3109, which were used most frequently in Korea were abolished, and the KS A ISO $2859-0\~3$ which coincide with ISO standards were established 3 years ago, but the implementation rate is very slow. Starting next year the national examination for qualification process for the product quality related item will the started and the preparation is underway. This study will investigate the recent sampling inspection process of KS as well as SPC related KS overhaul problem and present the data to help workers in SPC related field. One of the main example will be on KS A ISO 2859-3 and will attempt to help those medium and small sized companies with examples.

• 한국문헌정보학회지
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• 제40권2호
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• pp.217-242
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• 2006

본 연구는 국내 문헌정보학분야의 대표적인 4개 학술지에 2001부터 2004까지 발표된 792편의 연구논문 중 추론통계를 사용한 86편의 연구논문에서 활용한 데이터 수집방법과 추론통계기법을 비평적으로 고찰하였다. 표집방법별로 그리고 신뢰도검사와 가설과 모형의 검정에 사용된 통계기법별로 대표 연구논문을 소개하고, 사용된 기법으로 데이터를 수집하고 분석하는 과정에서 보인 문제점들을 논의하였다. 분석된 연구에서 표집방법으로는 확률표집보다는 비확률표집이 주로 사용되었으며, 질문지를 이용하여 데이터를 수집한 연구의 평균응답률은 74.47%로 분석되었으나, 응답률이 낮을 경우 무응답으로 인한 표집과정의 오류를 밝히려는 노력은 부족한 것으로 파악되었다. 추론통계기법 중 특히 신뢰도검사, 교차분석, 다중회귀분석, 요인분석, 다차원척도를 사용하는데 문제가 있는 것으로 분석되었다.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.194-207
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• 2000

In this paper, we suggest a vision-based lane change control system, which can be applied on the straight road, without additional sensors such as a yaw rate sensor and a lateral accelerometer. In order to reduce the image processing time, we predict a reference line position during lane change using the lateral dynamics and the inverse perspective mapping. The sliding mode control algorithm with a boundary layer is adopted to overcome variations of parameters that significantly affects a vehicle`s lateral dynamics and to reduce chattering phenomenon. However, applying the sliding mode control to the system with a long sampling interval, the stability of a control system may seriously be affected by the sampling interval. Therefore, in this paper, a look ahead offset has been used instead of a lateral offset to reduce the effect of the long sampling interval due to the image processing time. The control algorithm is developed to follow the desired trajectory designed in advance. In the design of the desired trajectory, we take account of the constraints of lateral acceleration and lateral jerk for ride comfort. The performance of the suggested control system is evaluated in simulations as well as field tests.

• 디지털산업정보학회논문지
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• 제11권1호
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• pp.171-182
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• 2015

The general wavelet transform has profitable property in non-stationary signal analysis specially. The tunable Q-factor wavelet transform is a fully-discrete wavelet transform for which the Q-factor Q and the asymptotic redundancy r, of the transform are easily and independently specified. In particular, the specified parameters Q and r can be real-valued. Therefore, by tuning Q, the oscillatory behavior of the wavelet can be chosen to match the oscillatory behavior of the signal of interest, so as to enhance the sparsity of a sparse signal representation. The TQWT is well suited to fast algorithms for sparsity-based inverse problems because it is a Parseval frame, easily invertible, and can be efficiently implemented. The transform is based on a real valued scaling factor and is implemented using a perfect reconstruction over-sampled filter bank with real-valued sampling factors. The transform is parameterized by its Q-factor and its over-sampling rate, with modest over-sampling rates being sufficient for the analysis/synthesis functions to be well localized. This paper describes filter design of 2D discrete-time wavelet transform for which the Q-factor is easily specified. With the advantage of this transform, perfect reconstruction filter design and implementation for performance improvement are focused in this paper. Hence, the 2D transform can be tuned according to the oscillatory behavior of the image signal to which it is applied. Therefore, application for performance improvement in multimedia communication field was evaluated.

• 컴퓨터교육학회논문지
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• 제18권5호
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• pp.63-70
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• 2015

상호 연관되는 복잡한 데이터 조건이 존재하는 환경에서 스카이라인 질의는 의사결정 시스템 등 폭넓은 애플리케이션 활용 가능성으로 다양한 분야에서 연구되어 왔다. 중앙집중식 환경에서 스카이라인 질의처리 기법이 초기에 제안되었으며 최근 대량의 다차원 데이터에 대해 데이터 공간을 분할하여 맵/리듀스 플랫폼 상에서 병렬적으로 처리하는 기법이 제안되었다. 그러나 현재까지의 기법이 비균등적 실행과 높은 중복 작업으로 효율성이 저하된다는 문제점을 배경으로 본 논문에서는 랜덤 샘플링을 통해 데이터 분포를 추정하여 비균등 분할 문제를 해결하고 각 기반의 데이터 공간을 분할하여 스카이라인 처리 과정에서 중복 작업을 최소화한 새로운 기법 MR-DEAP를 제안한다. 마지막으로 다양한 환경에서의 실험결과 제안된 기법이 다른 각 기반 분할과 그리드 분할 기법보다 우수한 것을 입증하였다.

• 전자공학회논문지 IE
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• 제43권3호
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• pp.6-12
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• 2006

이 논문은 100MHz 수준의 고속 신호 샘플링을 위해 글리치 최소화 기법을 적용한 8비트 100MHz CMOS D/A 변환기 (Digital to Analog Converter : DAC) 회로를 제안한다. 제안하는 DAC는 $0.35{\mu}m$ Hynix CMOS 공정을 사용하여 설계 및 레이아웃을 하였으며, 응용되는 시스템의 속도, 해상도 및 면적 등의 사양을 고려하여 전류 모드 구조로 적용되었다. D/A 변환기의 선형 특성은 설계한 Spec. 과 유사하였으며, $\pm$0.09LSB 정도의 DNL과 INL 오차가 측정되었다. 제작된 칩 테스트 결과에 대한 오동작의 원인을 분석하였으며, 이를 통하여 칩 테스트를 위한 고려사항 등을 제안하였다.

• 한국환경농학회지
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• 제25권3호
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• pp.262-267
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• 2006

Increased application of glyphosate (Gly) in glyphosate-resistant (GR) soybean cropping systems may affect rhizospheric microorganisms including IAA-producing rhizobacteria (IPR) and their effect on the growth of soybean. This field experiment was conducted to assess IPR populations in the rhizosphere of GR soybean ('Roundup-Ready' DeKalb DKB38-52) treated with glyphosate and foliar amendment treatments such as $PT21^{(R)}$ (urea solution with N 21 %) and $Grozyme^{(R)}$ (Biostimulant: mixtures of micro nutrients and enzymes). Effects of herbicide, sampling date, and their interaction on total bacterial numbers were significant (P < 0.001, 0.001, 0.013, respectively). Total bacteria (TB) numbers were increased with glyphosate treatment at 20 d after application and highest TB populations were associated with $Grozyme^{(R)}$ application, possibly due to the additional substrate from this product. The IPR of the soybean rhizosphere was significantly affected by herbicide, sampling date, and the herbicide*foliar amendment interaction. The ratios of numbers of IPR to TB ranged from 0.79 to 0.99 across the sampling dates irrespective of treatments. IPR numbers were slightly hindered by glyphosate application regardless of foliar amendment.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.763-772
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• 2019

There is a need to use sheath flow nozzle to detect bioaerosol such as virus and bacteria due to their characteristics. In order to enhance the detection performance depending on nozzle parameters, numerical analysis was carried out using a commercial code, ANSYS CFX. Eulerian-lagrangian approach method is used in this simulation. Multiphase flow characteristics between primary fluid and solid were considered. The detection performance was evaluated based on the results of flow field in nozzle chamber such as focusing efficiency and swirl strength. In addition, Latin hypercube sampling(LHS) of design of experiment(DOE) was used for generating a near-random sampling. Then, the acceleration section is optimized using response surface method(RSM). Results show that the optimized model achieved a 6.13 % in a focusing efficiency and 11.47 % increase in swirl strength over the reference model.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.825-836
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• 2019

One of the most challenging safety precautions for workers in dynamic, radioactive environments is avoiding radiation sources and sustaining low exposure. This paper presents a sampling-based algorithm, DL-RRT*, for minimum dose walk-path re-planning in radioactive environments, expedient for occupational workers in nuclear facilities to avoid unnecessary radiation exposure. The method combines the principle of random tree star ($RRT^*$) and $D^*$ Lite, and uses the expansion strength of grid search strategy from $D^*$ Lite to quickly find a high-quality initial path to accelerate convergence rate in $RRT^*$. The algorithm inherits probabilistic completeness and asymptotic optimality from $RRT^*$ to refine the existing paths continually by sampling the search-graph obtained from the grid search process. It can not only be applied to continuous cost spaces, but also make full use of the last planning information to avoid global re-planning, so as to improve the efficiency of path planning in frequently changing environments. The effectiveness and superiority of the proposed method was verified by simulating radiation field under varying obstacles and radioactive environments, and the results were compared with $RRT^*$ algorithm output.