• 가정과삶의질연구
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• 제22권3호
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• pp.35-46
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• 2004

The purpose of this study was to examine the residents' opinions on the degree of importance, and satisfaction with, the managerial service of multi-family housing. Residents' participation in managerial activities was also examined, because residents' opinions should be taken into serious consideration in order to improve the efficiency of housing management. Research methods used in this study were survey, field study, and content analysis of professionals' opinions. Survey data of 520 residents who live in multi-family housing were analyzed by means, frequencies, correlation, chi-square tests, t-tests, one-way ANOVA, post-hoc estimation (Scheffee test), and regression. The major findings of this study were as follows: First, many residents were dissatisfied with the quality of managerial service, but they thought that managerial services were very important. For example, they thought that safety inspection of the playground was very important, yet the current level of service was not satisfactory. Second, the characteristics of residents that determined the degree of residential satisfaction were income the location of the residence, and degree of participation in the community events. Third, the residents generally did not want to participate in the managerial services and community programs through such activities as participation in resident committee. In order to improve the housing management efficiency, residents' participation is critical. Some participants in this study pointed out that the details of management service and future plans need to be made public. New management models need to be developed to promote residents' participation and increase their satisfaction in the management.

• 전기학회논문지
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• 제61권11호
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• pp.1656-1661
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• 2012

UV inspection technology is being used for predictive maintenance of power facility together with IR-thermography and ultrasonic devices. In this paper, the UV corona camera design, fabrication, and perform a simple test to be take advantage of the diagnostic equipment. The UV corona camera developed a $6.4^{\circ}{\times}4.8^{\circ}$ of the field of view as a conventional camera to diagnose a wide range of slightly enlarged, and power equipment to measure the distance between the camera and the distance meter has been attached. The transmission between 250 to 280nm was 11% ($12.5%{\times}88%{\times}98%$) by combing the transmission on absorption film, window and other filter(UG 5, nickel sulphate and so on). In a distance of 5m with the UV corona camera it is possible to detect partial discharge with a PD level of 2.5pC and a RIV level of $3.6dB{\mu}V$.

• Agricultural and Biosystems Engineering
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• 제4권1호
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• pp.16-21
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• 2003

In the agricultural field, a machine vision system has been widely used to automate most inspection processes especially in quality grading. Though machine vision system was very effective in quantifying geometrical quality factors, it had a deficiency in quantifying color information. This study was conducted to evaluate color of beef using machine vision system. Though measuring color of a beef using machine vision system had an advantage of covering whole lean tissue area at a time compared to a colorimeter, it revealed the problem of sensitivity depending on the system components such as types of camera, lighting conditions, and so on. The effect of color balancing control of a camera was investigated and multi-layer BP neural network based color calibration process was developed. Color calibration network model was trained using reference color patches and showed the high correlation with L*a*b* coordinates of a colorimeter. The proposed calibration process showed the successful adaptability to various measurement environments such as different types of cameras and light sources. Compared results with the proposed calibration process and MLR based calibration were also presented. Color calibration network was also successfully applied to measure the color of the beef. However, it was suggested that reflectance properties of reference materials for calibration and test materials should be considered to achieve more accurate color measurement.

• 천문학회보
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• 제43권2호
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• pp.53.2-53.2
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• 2018

We present newly discovered dwarf galaxy candidates in deep and wide-field images of NGC 1291 obtained with KMTNet. Through a visual inspection, we find ~ 13 candidates, for which central surface brightness ranges from ${\mu}_{0,R}{\sim}22.5$ to $26.5mag\;arcsec^{-1}$. Adopting the distance to NGC 1291, the candidate dwarfs are brighter than $M_R=-12.5mag$ and their effective radii range from 350 pc to 1.4 kpc. Structural and photometric properties of dwarf candidates near NGC 1291 appears to be consistent with those of ordinary dwarf galaxies in nearby galaxies. We conduct the imaging simulation in order to find an optimal way to detect dwarf galaxies in KMTNet images and to test the completeness of our detection algorithm. We plan to apply this method to deep KMTNet images of other nearby galaxies obtained through KMTNet Nearby Galaxy Survey (KNGS).

• 천문학회보
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• 제44권1호
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• pp.80.2-80.2
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• 2019

We present newly discovered dwarf galaxy candidates in deep wide-field images of NGC 1291 obtained with KMTNet. We initially identify 20 dwarf galaxy candidates through visual inspection. 13 out of 20 appears to be high priority candidates, according to their central surface brightness (${\mu}_{0,R}{\sim}22.5$ to $26.5mag\;arcsec^{-2}$) and effective radii (350 pc to 1 kpc). Structural and photometric properties of dwarf candidates appear to be consistent with those of ordinary dwarf galaxies in nearby groups and clusters. Using imaging simulations, we demonstrate that our imaging data is complete up to $26mag\;arcsec^{-2}$ with > 70% of the completeness rate. In order to find an optimal way to automate detecting dwarf galaxies in our dataset, we test detection methods by varying parameters in SExtractor. We find that the detection efficiency from the automated method is relatively low and the contamination due to the artifacts is non-negligible. Therefore, it can be only applicable for pre-selection. We plan to conduct the same analysis for deep images of other nearby galaxies obtained through KMTNet Nearby Galaxy Survey (KNGS).

• Smart Structures and Systems
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• 제30권4호
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• pp.385-395
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• 2022

Detecting cracks on a concrete structure is crucial for structural maintenance, a crack being an indicator of possible damage. Conventional crack detection methods which include visual inspection and non-destructive equipment, are typically limited to a small region and require time-consuming processes. Recently, to reduce the human intervention in the inspections, various researchers have sought computer vision-based crack analyses: One class is filter-based methods, which effectively transforms the image to detect crack edges. The other class is using deep-learning algorithms. For example, convolutional neural networks have shown high precision in identifying cracks in an image. However, when the objective is to classify not only the existence of crack but also the types of cracks, only a few studies have been reported, limiting their practical use. Thus, the presented study develops an image processing procedure that detects cracks and classifies crack types; whether the image contains a crazing-type, single crack, or multiple cracks. The properties and steps in the algorithm have been developed using field-obtained images. Subsequently, the algorithm is validated from additional 227 images obtained from an open database. For test datasets, the proposed algorithm showed accuracy of 92.8% in average. In summary, the developed algorithm can precisely classify crazing-type images, while some single crack images may misclassify into multiple cracks, yielding conservative results. As a result, the successful results of the presented study show potentials of using vision-based technologies for providing crack information with reduced human intervention.

• 대한토목학회논문집
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• 제38권5호
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• pp.751-760
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• 2018

현재 다짐공사는 작업자가 정해진 다짐횟수, 두께, 속도, 진동여부 등을 자신의 경험에 의해 개별적으로 판단하고 감독자의 육안 검사에 의해 다짐공사의 품질측정이 이루어지고 있으며, 작업 후 대표성이 떨어지는 재래식 다짐강도 측정방법인 일점시험(Spot test)을 통하여 후속 단계의 작업을 진행하고 있는 실정이다. 따라서 다짐작업 결과에 대한 정량적 확인이 불가능하며, 시공부실로 인한 문제점이 제기될 가능성이 상존하고 있다. 본 연구에서는 여러 가지 시험조건에서 실제 현장규모로 다짐을 수행한 후 연속 다짐강도 측정 방법과 재래식 다짐강도 측정 방법과의 비교를 통해 연속 다짐강도 측정 방법의 사용 타당성을 입증하였다. 타당성 입증은 연속 다짐강도 측정방법인 GPS (Global Positioning System)와 가속도계로 구성된 IC (Intelligent Compaction) 롤러의 CMV (Compaction Meter Value)를 분석하는데 있으며, 입증된 결과를 토대로 일점시험을 배제한 현장 전 범위 품질확인이 가능하다. 품질 확인은 본 연구에서 개발한 다짐공사 관제프로그램에 시각화되며, 이를 통해 현장관리자는 다짐작업과 동시에 실시간 품질 모니터링이 가능하다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.120-128
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• 2019

지진 발생 시 발전소 내 운용설비의 구조적, 기능적 손상이 발생됨에 따라 국내 발전소에 설치된 운용설비의 정착부에 설치된 앵커 볼트에 대한 구조성능 평가 및 안정성 검토는 매우 중요하다. 본 연구에서는 국내 발전소 내 설치된 발전설비들의 현장조사를 통하여 콘크리트 슬래브 균열 발생에 따른 정착부 앵커볼트의 구조성능평가를 수행하였다. 대상 구조물로는 대전광역시에 위치한 대청수력발전소를 모델로 고려하였으며 운용설비 정착부에 현장 설치된 앵커볼트는 M12 J형 선 설치 볼트로 조사, 선정하였다. 실험 시 고려된 시험기준은 미국 ACI355.4와 유럽기준 ETAG 001이며 내진성능 정적평가를 위한 균열 발생을 구현하기 위하여 스테인리스 강판을 이용하여 인위적인 균열을 발생시켰다. 최종적으로 균열 폭 0.5mm 발생에 따른 콘크리트 고정용 선설치 앵커에 대하여 ASTM E 488-96에 근거하여 인발 및 전단성능평가를 수행하였다. 실험 결과, M12 J형 선 설치 앵커볼트의 인발 및 전단성능의 경우, 국내 설계하중과 비교 시 모두 만족하는 결과를 확인하였다. 인발성능의 경우 설계 값 대비 약 35% 높은 것으로 확인되었으며 전단성능의 경우 설계 값보다 약 7% 높은 것으로 확인되었다.

• Journal of Radiation Protection and Research
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• 제48권4호
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• pp.167-174
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• 2023

Background: A nondestructive test is commonly used to inspect the surface defects and internal structure of an object without any physical damage. X-rays generated from an electron accelerator or a tube are one of the methods used for nondestructive testing. The high penetration of X-rays through materials with low atomic numbers makes it difficult to discriminate between these materials using X-ray imaging. The interaction characteristics of neutrons with materials can supplement the limitations of X-ray imaging in material discrimination. Materials and Methods: The radiation image acquisition process for air-cargo security inspection equipment using X-rays and neutrons was simulated using a GEometry ANd Tracking (Geant4) simulation toolkit. Radiation images of phantoms composed of 13 materials were obtained, and the R-value, representing the attenuation ratio of neutrons and gamma rays in a material, was calculated from these images. Results and Discussion: The R-values were calculated from the simulated X-ray and neutron images for each phantom and compared with those obtained in the experiments. The R-values obtained from the experiments were higher than those obtained from the simulations. The difference can be due to the following two causes. The first reason is that there are various facilities or equipment in the experimental environment that scatter neutrons, unlike the simulation. The other is the difference in the neutron signal processing. In the simulation, the neutron signal is the sum of the number of neutrons entering the detector. However, in the experiment, the neutron signal was obtained by superimposing the intensities of the neutron signals. Neutron detectors also detect gamma rays, and the neutron signal cannot be clearly distinguished in the process of separating the two types of radiation. Despite these differences, the two results showed similar trends and the viability of using simulation-based radiation images, particularly in the field of security screening. With further research, the simulation-based radiation images can replace ones from experiments and be used in the related fields. Conclusion: The Korea Atomic Energy Research Institute has developed air-cargo security inspection equipment using neutrons and X-rays. Using this equipment, radiation images and R-values for various materials were obtained. The equipment was reconstructed, and the R-values were obtained for 13 materials using the Geant4 simulation toolkit. The R-values calculated by experiment and simulation show similar trends. Therefore, we confirmed the feasibility of using the simulation-based radiation image.

• 한국측량학회지
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• 제27권4호
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• pp.421-428
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• 2009

우리나라는 급경사의 산악지형이 많으며, 계절에 따른 집중호우가 나타나므로 하천유량변동의 정도가 매우 크다. 이러한 자연적 조건은 수자원의 관리에 있어 난점으로 작용하고 있으며, 정확한 하천 지역의 현황 파악에 있어서도 현실적으로 많은 어려움이 있기 때문에 이러한 문제점들을 해결하기 위하여 하천의 현황 파악 및 하천관리의 필요성이 지속적으로 증가되어 왔다. 본 연구에서는 하천의 현황을 파악하고, 관리하는데 적용하기 위하여 ALS와 MBES 측량기술을 이용하여 하천지 역에서 DEM 성과를 취득한 후, 그 성과가 접합되는 지역의 단일 DEM을 구축하였으며, 현장검측을 통하여 중첩지역에 대한 성과 검증을 수행하였다. 현장검측은 대상지역 내에서 검정장 2개 구역을 선정한 후, 토탈스테이션을 이용하여 구역 당 10여점을 측정하고 이를 ALS와 MBES데이터를 이용하여 구축한 TIN과 비교하였다. 비교검증 결과, NO.1 검정장의 RMSE는 0.322m, NO.2 검정장의 RMSE는 0.113m로 산출되었다. 이러한 결과는 ALS와 MBES 자료를 융합하여 하천지역의 DEM 을 구축하여 활용하는 가능성을 보였으며 (NO.2의 경우), NO.1의 경우에서 나타났듯이 향후 보다 나은 융합 방법에 대한 연구가 필요함을 시사하였다.