• 비파괴검사학회지
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• 제7권2호
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• pp.16-26
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• 1988

In the in-service inspections for the steam generator tubing of the nuclear power plants by the Eddy Current Testing, the ECT signals are evaluated by their phase. If oxidized copper sludge is piled up in the secondary side, however, big sludge signals occur in large quantities which originate from copper layers forming in the sludge piles due to the pitting mechanism of the steam generator tubing by $Cu^{2+}$, and modulate the defect signals, causing the difficulty in the defect detection. In this research, sludge specimens were prepared considering the formations of the sludge signal sources and multi-frequency ECT mixing experiments by different choices of the mixing standards were performed. The results were found to be 5 to 30% of the tube wall thickness over-estimated. Experiments using the ring-type mixing standards showed the least errors of all, while those with the mixing standards nearing the sludge conditions brought larger errors as a result of the influence of the interference between the defect and the copper layers.

• Progress in Superconductivity
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• 제5권2호
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• pp.94-97
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• 2004

Step-edge Josephson junctions (SEJ) have been fabricated on sapphire substrates with in situ deposited films of CeO$_2$ buffer layer and YBa$_2$Cu$_3$O$_{7}$ films on the low angle steps. Direct coupled SQUID magnetometers with the SEJ were formed on 1 cm X 1 cm R-plane sapphire substrates. Typical 5-${\mu}{\textrm}{m}$-wide Josephson junctions have R$_{N}$ of 3 Ω and I$_{c}$ of 50 $mutextrm{A}$ at 77 K. The direct coupled SQUID magnetometers were designed to have pickup coils of 50-${\mu}{\textrm}{m}$-wide 16 parallel loops on the 1 cm X 1 cm substrates with outer dimension of 8.8 mm X 8.8 mm. The SEJ SQUID magnetometers exhibit relatively low 1/f noise even with dc bias control, and could be stably controlled by flux-locked loops in the magnetically disturbed environment. Field noise of the do SQUID was measured to be 200∼300 fT/Hz$^{1}$2/in the white noise region and about 2 pT/Hz$^{1}$2/ at 1 Hz when measured with dc bias method.hod.d.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.275-275
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• 2012

The relative composition of $Cu(InGa)Se_2$ solar cells is one of the most important measurement issues. However, quantitative analysis of multi-component alloy films is difficult by surface analysis methods due to severe matrix effect. In this study, quantitative depth profiling analysis of CIGS films was investigated by secondary ion mass spectrometry (SIMS). The compositions were measured by SIMS using the alloy reference relative sensitivity factors derived from the certified compositions and the total counting numbers of each element. The compositions measured by SIMS were linearly proportional to those by inductively coupled plasma-mass spectrometry (ICP-MS) using isotope dilution method. In this study, the quantification measured by ICP-MS method is compared with the composition calculated by SIMS depth profiles with AR-RSFs obtained from the reference. The SIMS depth profile of CIGS thin films according to the manufacturing condition was converted into compositional depth profile.

• 대한산업공학회지
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• 제39권4호
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• pp.298-312
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• 2013

This paper compares efficiency results and performance targets for academic departments in a local private college using DEA (Data Envelopment Analysis). Because of an aging society, a smaller school-age population entering colleges, and enhanced accreditation standards by the government, colleges and universities are not recruiting and retaining sufficient students and therefore are struggling for survival. In contrast to popular four-year undergraduate universities concentrated in Seoul and its satellite cities, retaining students is critical for the survival of local private colleges in poor or remote regions. Therefore, it is very important to identify the factors involved in the retention of students in the various departments of a college. However, given the different characteristics of the departments, it is difficult to identify one unique or robust set of standards to evaluate their performance. The purpose of this paper is to maximize student retention capabilities by ensuring that additional resources are assigned to efficient DMUs, while, inefficient DMUs are given benchmarked targets. Based on previous studies and college accreditation standards, this paper presents indices to be used in evaluating the efficiency of academic departments in a college. In evaluating relative efficiency, this paper uses the output-oriented BCC model. To define target levels to be achieved for efficient DMU, a multi-stage DEA procedure is used.

• 한국자기학회지
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• 제5권5호
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• pp.905-909
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• 1995

전원주파수 교류자기장 내성평가을 위하여 유도코일용 대형 3-축 사각 헬름홀쯔 코일 를 설계 .center dot. 제작하였다. 제작한 사각 헬름홀쯔 코일의 코일상수및 자기장 균일도를 측정하였으며, 3축 방향의 자기장 균일도는 컴퓨터 모사에의한 값과 잘 일치하였다. 자기장 균일도부터 교류자기장 내성평가에서 요구하는 유효시험공간을 결정 하였으며, 다회의 유도코일을 사용하므로써 낮은 전류로 큰 자기장을 요구하는 단속적 교류자기장 내성평가도 수행할 수 있음을 알 수 있었다.

• 정보처리학회논문지C
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• 제18C권5호
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• pp.317-326
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• 2011

본 논문은 다양한 보안방어 정책과 기기들이 산재해 있으나, 이를 표준화하여, 각 방어정책의 특성과 방어기법을 새롭게 정의함으로써 기존 네트워크 인프라 구현을 포함한 새로운 보안정책 도입 및 추가 구현 시 관리자 또는 사용자가 손쉽게 정책을 추가하고 바로 적용 가능하도록 각 보안 분야별 정책과 기기를 명세 보고서화 하는데 의의가 있다. 따라서 하나의 네트워크 보안기기를 기반으로 부여 가능한 정책들을 분류하는 ONSU-MF(One Network Security Unit-Multi Function)기법과 하나의 보안기기로 다양한 보안방안을 구현하는 OSD-MD(One Security Device-Multi Defense)기법으로 구분하고 이를 통합한 표준화 구현기법을 통해 향후 네트워크 보안 인프라 개선 메커니즘을 제안코자 한다.

• 대한간호학회지
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• 제39권3호
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• pp.409-421
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• 2009

Purpose: In this research multi-level analysis was done to identify factors related to quality of services. Patient characteristics and organizational factors were considered. Methods: The data were collected from the Health Insurance Review and Assessment Service(HIRA) data base. The sample was selected from 17,234 patients who had been admitted between January 2007 and May 2008 to one of 253 long-term care hospitals located in Seoul, six other metropolitan cities or nine provinces The data were analyzed with SAS 9.1 using multi-level analysis. Results: The results indicated that individual level variables related to quality of service were age, cognitive ability, patient classification, and initial quality scores. The organizational level variables related to quality of service were ownership, number of beds, and turnover rate. The explanatory power of variables related to organizational level variances in quality of service was 23.72%. Conclusion: The results of this study indicate that differences in the quality of services were related to organizational factors. It is necessary to consider not only individual factors but also higher-level organizational factors such as nurse' welfare and facility standards if quality of service in long term care hospitals is to be improved.

• Journal of Mechanical Science and Technology
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• 제17권10호
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• pp.1411-1422
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• 2003

The detection of free spaces between obstacles in a scene is a prerequisite for navigation of a mobile robot. Especially for stereo vision-based navigation, the problem of correspondence between two images is well known to be of crucial importance. This paper describes multi-range approach of area-based stereo matching for grid mapping and visual navigation in uncertain environment. Camera calibration parameters are optimized by evolutionary algorithm for successful stereo matching. To obtain reliable disparity information from both images, stereo images are to be decomposed into three pairs of images with different resolution based on measurement of disparities. The advantage of multi-range approach is that we can get more reliable disparity in each defined range because disparities from high resolution image are used for farther object a while disparities from low resolution images are used for close objects. The reliable disparity map is combined through post-processing for rejecting incorrect disparity information from each disparity map. The real distance from a disparity image is converted into an occupancy grid representation of a mobile robot. We have investigated the possibility of multi-range approach for the detection of obstacles and visual mapping through various experiments.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.699-707
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• 2015

Although digit character recognition has got a significant improvement in recent years, it is still challenging to achieve satisfied result if the data contains an amount of distracting factors. This paper proposes a novel digit character recognition approach using a multi-layer hierarchical model, Hybrid Restricted Boltzmann Machines (HRBMs), which allows the learning architecture to be robust to background distracting factors. The insight behind the proposed model is that useful high-level features appear more frequently than distracting factors during learning, thus the high-level features can be decompose into hybrid hierarchical structures by using only small label information. In order to extract robust and compact features, a stochastic 0-1 layer is employed, which enables the model's hidden nodes to independently capture the useful character features during training. Experiments on the variations of Mixed National Institute of Standards and Technology (MNIST) dataset show that improvements of the multi-layer hierarchical model can be achieved by the proposed method. Finally, the paper shows the proposed technique which is used in a real-world application, where it is able to identify digit characters under various complex background images.

• Journal of information and communication convergence engineering
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• 제13권4호
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• pp.235-240
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• 2015

A decimation chain for multi-standard reconfigurable radios is presented for 900-MHz and 1,900-MHz dual-band cellular standards with a data interpolator based on the Lagrange method for adjusting the variable data rate to a fixed data rate appropriate for each standard. The two proposed configurations are analyzed and compared to provide insight into aliasing and the signal bandwidth by means of a newly introduced measure called interpolation error. The average interpolation error is reduced as the ratio of the sampling frequency to the signal BW is increased. The decimation chain and the multi-rate analog-to-digital converter are simulated to compute the interpolation error and the output signal-to-noise ratio. Further, a method to operate the above-mentioned chain under a compressed mode of operation is proposed in order to guarantee continuous packet connectivity for inter-radio-access technologies. The presented decimation chain can be applied to LTE, WCDMA, GSM multi-mode multi-band digital front-end which will ultimately lead to the software-defined radio.