• 한국정밀공학회지
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• 제22권1호
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• pp.183-192
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• 2005

This study compared cerebral lateralization index based on the area of neural activation with that based on the intensity of neural activation. For this purpose, 8 right-handed male college students (the mean age - 23.5 years) and 10 right-handed male college students (the mean age - 25.1 years) participated respectively in researches on visuospatial and verbal task brain function. Functional brain images were taken from 3T MRI using the single-shot EPI method. The result of measuring cerebral lateralization index based on the area of neural activation suggested that the right hemisphere is dominant in visuospatial tasks and the left one is in verbal tasks. However, the dominance is not sufficient to locate the exact part of the brain for these tasks. When cerebral lateralization index was computed based on the intensity of neural activation, it was derived that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobes. Thus, cerebral lateralization index by area based on the intensity of neural activation as proposed by this study can determine the dominance of the cerebrum by area, so is helpful for accurate and quantitative determination of cerebral lateralization.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.95-101
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• 2007

Recently, small-animal imaging technology has been rapidly developed for longitudinal screening of laboratory animals such as mice and rats. One of newly developed imaging modalities for small animals is an x-ray micro-CT (computed tomography). We have developed two types of x-ray micro-CT systems for small animal imaging. Both systems use flat-panel x-ray detectors and micro-focus x-ray sources to obtain high spatial resolution of $10{\mu}m$. In spite of the relatively large field-of-view (FOV) of flat-panel detectors, the spatial resolution in the whole-body imaging of rats should be sacrificed down to the order of $100{\mu}m$ due to the limited number of x-ray detector pixels. Though the spatial resolution of cone-beam CTs can be improved by moving an object toward an x-ray source, the FOV should be reduced and the object size is also limited. To overcome the limitation of the object size and resolution, we introduce zoom-in micro-tomography for high-resolution imaging of a local region-of-interest (ROI) inside a large object. For zoom-in imaging, we use two kinds of projection data in combination, one from a full FOV scan of the whole object and the other from a limited FOV scan of the ROI. Both of our micro-CT systems have zoom-in micro-tomography capability. One of both is a micro-CT system with a fixed gantry mounted with an x-ray source and a detector. An imaged object is laid on a rotating table between a source and a detector. The other micro-CT system has a rotating gantry with a fixed object table, which makes whole scans without rotating an object. In this paper, we report the results of in vivo small animal study using the developed micro-CTs.

• 대한의용생체공학회:의공학회지
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• 제37권4호
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• pp.140-146
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• 2016

The ultrasound imaging in medical diagnosis has become a popular modality because of its safe, noninvasive, portable, relatively inexpensive, and provides a real-time image formation. However, usefulness of ultrasound imaging is at times limited due to the presence of signal-dependent noise like as speckle. Therefore, noise reduction is very important, as various types of noise generated limits the effectiveness of medical image diagnosis. This paper introduces a speckle noise reduce algorithm using total variation denoising (TVD) in Laplacian pyramid. With this method, speckle is removed by TVD of bandpass ultrasound images in Laplacian pyramid domain. For TVD in each pyramid layer, a ${\lambda}$ is selected by trial-and-error method. The visual comparison of despeckled 'in vivo' ultrasound images from pancreas shows that the proposed method could effectively preserve edges and detailed structures while thoroughly suppressing speckle. For a Simulated B-mode image, contrast-to-noise-ratio (CNR) and signal-to-noise-ratio (SNR) were obtained like 4.65 dB and 14.11 dB, respectively. The results show that the proposed method can conduct better than some of the existing methods in terms of the CNR and the SNR.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1998년도 추계학술대회 논문집
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• pp.114-117
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• 1998

Failure to link business or operations strategy with the activities of operations is a critical problem in strategy implementation process. This problem comes from malfunction of a coordination and control mechanism to support the strategic direction by effective communication throughout the firm. A performance measurement and evaluation system (PMES) is thought as a core mechanism to monitor, direct. and induce desirable activities. We have developed a new strategic PMES (SPMES) that can effectively support the manufacturing strategy by utilizing customized performance measures. They are selected from a pool of four distinct but closely related sets of performance measures; financial, market, internal competency, and performance driver. In this paper, we briefly review the structure of the SPMES and explain the change process of PMES into SPMES in manufacturing business units. First we analyze the business environment and manufacturing strategy to identify short- and long-term issues facing the management. Next step is scrutinizing the objectives and activities of every function and process in the business unit. Using the information obtained, we can diagnose the gaps between currently effective PMES and desirable SPMES supporting the strategies. Once the problems in existing system are identified, we reconfigure the existing and new measures to establish a SPMES through a series of analyses, discussions and workshops. In organizing the selected measures in the new system, we use AHP method to reflect the relative importance of the measures in a specific business. Finally, modification or development of information system to support the SPMES wraps up the development process, and implementation begins. We explain the entire process using two cases to clarify the real meanings and the difficulties of PMES change process.

• 경영과학
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• 제31권2호
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• pp.49-63
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• 2014

With the huge concerns on the inefficiency of public enterprises, particularly a significant amount of debt, an increasing number of studies have been carried out to analyze the levels of inefficiency and investigate the causes of that inefficiency. However, very limited range of analytical methodologies have been used in the efficiency analysis and moreover, the effects of external factors have been little addressed. This study explores the efficiency of urban railway corporations in Korea by utilizing a method of stochastic frontier analysis (SFA). In particular, the potential effects of external factors including residential and floating populations of a station were statistically analyzed. A total of seven Korean urban railway corporations were selected to compare each other in terms of operational efficiency. The results present three important findings. First, the Cobb-Douglas model was found to be more valid for SFA compared to the Translog model. Second, the efficiencies of urban railway corporations in Seoul and Busan are relatively high whereas those of Daejeon and Gwangju are very low in efficiency in the area of sales revenue. In an aspect of number of transport of passengers, Gwangju Metro also showed the lowest efficiency. Third, the external factors are significantly associated with the efficiency, indicating that the efficiencies of Daejeon Metro and Gwangju Metro would increase while the efficiency of Seoul Metro would decreases when the external variables are excluded in the efficiency analysis. The results provide several meaningful implications for managers of the urban railway corporations as well as policy makers who are attempting to resolve the inefficiency problems of public enterprises.

• 한국식품조리과학회지
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• 제23권3호통권99호
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• pp.281-287
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• 2007

본 연구에서는 김치를 활용한 다용도 소스 개발의 목적으로 배추김치를 제조하여 잘 숙성된 김치를 분쇄한 다음 부재료로 전분, 당, 식초, 소금을 혼합하여 김치소스를 제조한 후 5$^{\circ}$C에서 91일 동안 저장하면서 저장기간에 따른 품질특성 및 관능적 특성을 살펴보았다. 즉, 김치소스 제조는 배추김치에 부재료와 백년초분말을 1.0% 첨가한 것으로 하였다. 품질특성을 조사한 결과 pH의 경우 저장초기는 pH 4.1이다가 저장 91일이 되어도 거의 같은 수준을 유지하여 변화가 없게 나타났다. 총산도는 저장기간이 증가함에 따라 각 소스별 비슷한 경향으로 증가하였으나 큰 변화는 보이지 않았다. 색은 천연색소를 첨가하여 안정성을 나타내었으며, 비타민 C와 점도의 변화는 저장기간이 증가할수록 비슷한 경향으로 감소하는 경향을 보였다. 또한 저장기간별 김치소스의 총균수 및 유산균수의 변화를 살펴 본 결과 비슷한 양상으로서 저장초기에서 거의 변화가 없다가 저장 약 20일에는 약간 증가했다가 서서히 감소하기 시작하여 저장 91일까지는 거의 변화 없이 다소 저하되는 경향을 보였다. 관능적 특성은 저장기간에 따라 다소 유의적인 차이는 있었으며, 가공된 김치소스에서도 소비자기호도 조사에서 모든 평가 항목에서 높게 평가되었다.

• 자동차안전학회지
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• 제9권3호
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• pp.31-38
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• 2017

For years, Q1.5 (anthropomorphic test device for 1.5 years old infant) and Q3 (anthropomorphic test device for 3 years old infant) dummy protection has been improved considerably by the effort of EuroNCAP. ISOFIX strength of vehicle structure has increased and many child occupant protection tests have made child restraint system (hereafter CRS) optimized for child safety. However, from 2016, EuroNCAP changed the dummy which is used for the child occupant protection from Q1.5/Q3 to Q6/Q10 and these were also adopted in KNCAP from 2017. Therefore, a new method is required to secure the safety for older children In this research, child dummies were tested by using adult safety systems, and the different results from each adult restraint system were compared. Finally, dummies were tested with the CRS harness belt commonly used for infants, which has yielded significant result. In this research, mid-sized sedan and small SUV were used for the test. The researchers of this paper performed sled tests to correlate between the different adult safety belt system and child injury. Following the sled test, an actual vehicle test was conducted to gather the injury data of Q-dummy with the CRS harness belts. This paper will show the advantages of applying a pre-tensioner in the second row for child protection and the necessity of CRS which has its own harness belts to improve safety for older children.

• 대한의용생체공학회:의공학회지
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• 제41권5호
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• pp.195-202
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• 2020

Needle detection in ultrasound images is sometimes difficult due to obstruction of fat tissues. Accurate needle detection using continuous ultrasound (CUS) images is a vital stage of treatment planning for tissue biopsy and brachytherapy. The main goal of the study is classified into two categories. First, new detection model, i.e. D-Attention Unet, is developed by combining the context information of 3D medical data and CUS images. Second, the D-Attention Unet model was compared with other models to verify its usefulness for needle detection in continuous ultrasound images. The continuous needle images taken with ultrasonic waves were converted into still images for dataset to evaluate the performance of the D-Attention Unet. The dataset was used for training and testing. Based on the results, the proposed D-Attention Unet model showed the better performance than other 3 models (Unet, D-Unet and Attention Unet), with Dice Similarity Coefficient (DSC), Recall and Precision at 71.9%, 70.6% and 73.7%, respectively. In conclusion, the D-Attention Unet model provides accurate needle detection for US-guided biopsy or brachytherapy, facilitating the clinical workflow. Especially, this kind of research is enthusiastically being performed on how to add image processing techniques to learning techniques. Thus, the proposed method is applied in this manner, it will be more effective technique than before.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.41-41
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• 2018

안정적이고 효율적인 전력 공급을 위해 번화가 대로변 주변에 다수의 지상 변압기 및 개폐기가 설치되고 있으며, 이로 인해 불법 부착물로 인한 도시의 미관 훼손, 변압기 및 개폐기의 오염 등의 문제가 발생하고 있다. 따라서 각 산업체 및 연구 기관에서는 부착 방지용 코팅 도료 및 시트에 대해 다양한 연구개발을 진행하고 있으며, 현장에 적용되고 있는 사례도 있다. 하지만 현재 현장에 적용된 대부분의 제품들은 약 1년 정도의 시간이 지나면 고유의 기능을 상실하며, 도료 및 시트와 기판 사이의 박리가 일어나 우수한 성능을 보이지 않아, 결과적으로 도시에 더욱더 악영향을 주고 있다. 이러한 원인으로는 도료 및 시트의 성능 평가를 위한 다양한 규격들이 존재하지만, 테이프류 탈착 시 영향을 주는 인자(Factor)들이 명확하게 설정되어 있지 않고, 이에 대해 면밀하게 분석한 자료가 없으며, 정량적이고 객관적인 시험 방법이 고려되지 않고 있기 때문에 좋은 제품을 선별하기 어려운 상황이다. 따라서 여러 가지 제품들의 비교평가 및 기술 개발에 활용할 수 있는 가이드라인을 제시하기 위해 일반적으로 사용되고 있는 면테이프(Duct tape)를 이용하여 기판(Substrate)에 대해 다양한 인자를 기준으로 탈착 특성을 측정 및 평가하였다. 현재 지상 배전함 및 개폐기는 분체도장(Powder coating)으로 구성되어져 있으며, 그 모재는 탄소강(Carbon steel)으로 이루어져 있고, 소수의 경우 스테인리스(Stainless steel)를 사용하기 있기 때문에 분체도장(Powder coating), 탄소강(Carbon steel), 스테인리스(Stainless steel)를 기판으로 선정하여 탈착 특성을 평가했다. 탈착 특성에 관여하는 요인으로는 탈착 각도(Peeling angle), 탈착 속도(Peeling speed), 표면 조도(Surface roughness) 등이 있고, 상대 습도(Relative humidity)의 경우 탈착 특성에 영향을 거의 주지 않는 것을 확인했다. 탈착 시 각도가 클수록, 속도가 빠를수록, 조도가 작을수록 부착력(Peel resistance, N/cm)과 탈착 에너지(Energy, J)가 커지며, 탈착 특성에 영향을 주는 인자를 바탕으로 95% 신뢰도 구간을 적용한 탈착특성 모델링을 제시하였다. 이 모델링을 이용하여 실제 현장에서 발생할 수 있는 다양한 각도($90^{\circ}$, $180^{\circ}$)와 속도 범위(100 ~ 1500mm/min)에서의 탈착 특성을 추정하는 것으로, 좋은 성능 및 내구성을 가진 제품을 효과적으로 선별한다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.42.2-42.2
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• 2018

신도시 및 대규모 도시 개발이 진행됨에 따라 안정적이고 효율적인 전력 공급을 위해 다수의 지상 배전함이 설치되고 있으며, 이에 따라 불법 광고물 및 스티커의 부착으로 인한 문제가 발생하고 있다. 이를 해결하기 위하여 여러 기관 및 산업체에서는 부착 방지용 코팅 도료 및 시트에 대하여 다양한 연구개발을 진행하고 있으며, 현장에 적용 된 다수의 제품이 존재한다. 하지만 현재 대부분의 제품들은 약 1년 정도의 시간이 지나면 부착 방지 기능을 상실하며, 도료와 기판 또는 시트와 기판 사이의 박리가 일어나 도시의 미관을 더욱 해치는 결과를 초래하고 있다. 이러한 원인으로는 부착력(Peel resistance, N/cm)을 측정하는 기존의 제시된 방법(KS T 1028, Peel test)으로는 정확한 측정이 어렵기 때문에 제품 선별에 어려움이 있다. 일반 기판의 경우 규격에서 요구하는 각도($90^{\circ}$, $180^{\circ}$)가 잘 유지되어 정밀한 부착력 측정이 가능하지만, 저점착 기능성 코팅소재(Anti-adhesion coating)의 경우 부착 자체가 어렵기 때문에 요구 각도를 유지하기 어려워 정밀한 측정을 할 수 없다. 이러한 문제점들을 해결하고자 압입자(Probe)를 이용한 새로운 평가 장치와 방법(Tack test)을 개발 및 제시하였다. 평가 지표로는 최대 점착력(Adhesive force, N), 최대 점착력일 때 점착제가 늘어난 총 길이(Extension of adhesive, mm), 탈착 에너지(Energy, J)가 있으며, 인가하는 힘(N)이 커질수록, 탈착 속도(Velocity)가 빨라질수록 평가 지표 모두 값이 상승하는 경향성을 보인다. 각 시험방법(Peel test, Tack test)에 대한 테이프류 점착제와 기판과의 결합이 끊어지는(Debonding, 탈착) 메커니즘(Mechanism)은 점착제 기공(Cavity)의 형성, 결합이 끊어지는 힘(Debonding force, N), 힘의 평형(Force balance)로 설명 가능하며, 상호간의 관계성을 도출한다. 이와 같은 평가 지표를 활용하여 저점착 기능성 코팅소재에 대해 정밀한 평가를 하는 것으로, 향후 개발될 다양한 제품에 대한 성능 분별력을 높이고, 현장에 적용 될 제품들의 성능을 끌어 올려 기존에 발생한 다양한 문제점들을 해결 할 수 있다.