• Journal of Korea Spatial Information System Society
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• v.8 no.3
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• pp.105-115
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• 2006

A sensor network which uses DCS(Data-Centric Storage) stores the same data into the same sensor node. Thus it has a hot spot problem when the sensor network grows and the same data arise frequently. In the past researches of the sensor network using DCS, the hot spot problem caused by growing the sensor network was ignored because they only concentrated on managing stored sensor data efficiently. In this paper, we proposed a non-equal region split method that supports efficient scalability on storing multi-dimensional sensor data. This method can reduce the storing cost, as the sensor network is growing, by dividing whole space into regions which have the same number of sensor nodes according to the distribution of sensor nodes, and storing and managing sensor data within each region. Moreover, this method can distribute the energy consumption of sensor nodes by increasing the number of regions according to the size of the sensor network, the number of sensor nodes within the sensor network, and the quantity of sensor data. Therefore it can help to increase the life time and the scalability of the sensor network.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.1
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• pp.1-12
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• 2021

In the design of a tunnel boring machine (TBM), the excavation efficiency of the equipment depends on the design of the cutter head, which is directly in contact with the ground. Especially, the allocation of disc cutter is crucial issue. Disc cutters can be divided into center cutter zone, inner cutter zone and transition cutter zone depending on where they are placed. Many studies have been conducted to identify optimal cutting conditions for face cutters. However, research to determine the optimal cutting conditions for the transition cutter has been relatively incomplete. In this study, to identify the optimal cutting conditions for the transition cutter, numerical analysis using discrete element method was performed, and the specific energy curve according to the angle between the transition cutters was drawn to find out the optimum cutting conditions. The results show that the angle between the transition cutters showing minimum specific energy in the transition cutter zone is 9°. Transition cutter zone was divided into three sections according to the slope angle of the transition cutter. It is also found that, the greater the slope angle of the transition cutter. This finding shows good agreement with the present design of transition cutter zone.

• Geophysics and Geophysical Exploration
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• v.25 no.1
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• pp.14-25
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• 2022

The passive surface wave method measures seismic signals from ambient noises or vibrations of natural phenomena without using an artificial source. Since passive sources are usually in lower frequencies than artificial ones being able to ensure the information on deeper geological structures, the passive surface wave method can investigate deeper geological structures. In the passive method, frequency dispersion curves are obtained after data acquisition, and the dispersion curves are analyzed by assuming 1D-layered earth, which is like the method of active surface wave survey. However, when computing dispersion curves, the passive method first obtains and analyzes coherence curves of received signals from a set of receivers based on spatial autocorrelation. In this review, we explain how passive surface wave methods measure signals, and make data processing and interpretation, before analyzing field application cases.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.789-795
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• 2023

Digital-Twin are recognized as an important core technology for the realization of Smart Factories by simulating and optimizing the monitoring and predictive maintenance of manufacturing equipment and the operation of production lines in a digital space. To implement this system, we adopt the IEC62541-based OPC-UA (Open Platform Communications Unified-Architecture) Protocol, which has strengths in interoperability and connectivity between heterogeneous platforms. Therefore, In this paper, We designed and implemented an IIoT(Industry Internet of Things) system that connects heterogeneous platforms, and developed an OPC-UA simulator based on IEC 62541. We will present whether the data will be applied to the Digital-Twin Platform and whether it will work, and proceed with performance tests and evaluations. We evaluate the operation performance and OPC-UA performance of the Digital-Twin platform lightened by the proposed device, and present the optimal IEC62514-based simulator system. We proceeded with the performance evaluation of sending and receiving data with OPC-UA wrapping with the proposed simulator, and found that a lightweight Digital-Twin platform can be operated. This research can apply the OPC-UA protocol for implementing smart factory and meta-factory in the manufacturing shop floor with limited resources, avoiding the waste of time and space on the shop floor through the OPC-UA simulator. We expect that this will contribute to a significant improvement in efficiency by minimizing.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.671-677
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• 2023

When a scintillator block is constructed using fine scintillator pixels, the scintillator block located at the edge of the scintillator block results in overlapping images. To solve this problem, a light guide was inserted between the scintillator block and the photosensor, and images of all scintillation pixels were separated and acquired. However, loss of light may occur through the light guide, which eventually affects the quality of the image due to a decrease in energy resolution. Therefore, in this study, a detector was designed that can separate scintilltion pixels better by using a reflector on the side of the light guide and can secre excellent energy resolution by minimizing light loss. For comparative evaluation with previous studies, flood images were obtained through DETECT2000 capable of light simulation, and the degree of separation and light collection rate were evaluated. When a reflector was used on the side of the light guide, all materials showed excellent separation regardless of the material of the light guide, which showed better separation results than previous studies. In addition, the light collection rate was more that five times better when the reflector was applied than when it wa not. If this detector is applied to a small animal positron emission tomography, it will be possilbe to secre excellent image quality through excellent spatial resolution and energy resolution.

• The Journal of the Korea Contents Association
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• v.16 no.7
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• pp.681-688
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• 2016

This study assess their quality of radiation on analysis of the spectrum of resolution suggesting IEC 61267 in radiation quality that RQA3, RQA5, RQA7, RQA9 and combination of clinical condition using several quality of radiation. In experiments edge method first, the spatial resolution assessment used image of the additional filter and SID is obtained the IEC 62220-1, spatial resolution and sharpness of the obtained image was evaluated in the MTF value 10%(0.1), MTF value 50%(0.5) using a Matlab program. Second, MCNPX simulation used spatial resolution analysis was radiation quality particle fluence and spectrum analysis in energy. As a result, make use of additional filter, image quality evaluation of SID that RQA3 radiation quality combination qualification is higher spatial resolution and sharpness make unused of additional filter and SID 100cm. RQA7 radiation quality combination qualification is higher that spatial resolution make unused of additional filter and SID 150cm. RQA9 radiation quality combination qualification is higher that spatial resolution and sharpness make used of additional filter and SID 180cm. spectrum analysis of radiation quality by reducing consequent errors occurring in the experiment that error due to the reproducibility of the X-ray tube, occur in an error of correction the detector suggest ideal conditions from spectrum analysis through MCNPX simulation. In conclusion, by suggesting spatial resolution and sharpness of result for various radiation quality, It provide basic data that radiation quality condition and quantitative assessment method for laboratory in clinical using detector evaluation.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1025-1032
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• 2018

Snow Cover is a form of precipitation that is defined by snow on the surface and is the single largest component of the cryosphere that plays an important role in maintaining the energy balance between the earth's surface and the atmosphere. It affects the regulation of the Earth's surface temperature. However, since snow cover is mainly distributed in area where human access is difficult, snow cover detection using satellites is actively performed, and snow cover detection in forest area is an important process as well as distinguishing between cloud and snow. In this study, we applied the Normalized Difference Snow Index (NDSI) and the Normalized Difference Vegetation Index (NDVI) to the geostationary satellites for the snow detection of forest area in existing polar orbit satellites. On the rest of the forest area, the snow cover detection using $R_{1.61{\mu}m}$ anomaly technique and NDSI was performed. As a result of the indirect validation using the snow cover data and the Visible Infrared Imaging Radiometer (VIIRS) snow cover data, the probability of detection (POD) was 99.95 % and the False Alarm Ratio (FAR) was 16.63 %. We also performed qualitative validation using the Himawari-8 Advanced Himawari Imager (AHI) RGB image. The result showed that the areas detected by the VIIRS Snow Cover miss pixel are mixed with the area detected by the research false pixel.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.77-100
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• 2022

In the era of low growth, many provincial cities are experiencing population decline and aging. Population decline phenomena such as reduction of productive manpower, reduction of finances, deterioration of quality of life, and collapse of the community base are occurring in a chain and are being pushed to the brink of extinction of the cities. This study aims to propose a methodology to objectively estimate the employment creation centers and setting the basic unit of industrial-centered zoning by applying spatial statistical techniques and GIS for the application of the compact city plan as an efficient spatial management policy in a city with a declining population. In details, based on reviewing previous studies on compact city, 'employment complex index(ECI)' were defined considering the number of workers, the number of settlers, and the area of development land, the employment creation center was estimated by applying the 'Local Moran's I' and 'Getis-Ord's Hot-Spot Analysis'. As a case study, changes in the four years of 2013, 2015, 2017, and 2019 were compared and analyzed for Changwon City. As a result, it was confirmed that the employment creation center is becoming compacted and polycentric, which is a significant result that reflects the actual situation well. This results provide the basic data for functional and institutional territorial governance for the regional revitalization platform, and provide meaningful information necessary for spatial policy decision-making, such as population reduction, regional gross domestic product, and public facility arrangement that can respond to energy savings, transportation plans, and medical and health plans.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.51-57
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• 2014

A MILD(Moderate and Intense Low oxygen Dilution) combustion, which is effective in the reduction of NOx, is considerably affected by the recirculation flow position of hot exhaust gas to the combustion furnace. A numerical analysis was accomplished to elucidate the flow characteristics in the MILD combustion incinerator for several cases with or without exhaust gas recirculation. It could be seen from the result of the present numerical study that the flow recirculation could be observed in the upper region over the vertical dividing wall for the case without exhaust gas recirculation. The optimal position of exhaust gas recirculation position was derived by the comparison of %RMS of x directional velocity for the cases with exhaust gas recirculation. The case with the exhaust gas recirculation position at the upper right of free board was the most effective with the smallest value of 57.4% RMS.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.170-170
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• 2017

기후변화 따른 스마트팜 돈사 외부 환경의 변화에 대응하고, 사육 환경을 능동적으로 개선하기 위한 연구가 수행 중이다. 돈사 내 열전달 요소 간 상호 역학성 분석을 위해서 고려해야할 사항은 입기구, 보온 등, 열풍기, 단열제, 위치, 방향, 돈사의 연평균 온도, 습도, 연중 일사량, 가축의 열복사 등 상호 복잡하게 연관되어 있는 물리량이다. 돈사 전체 열손실, 자연발생 에너지량, 강제발생 에너지량, 난방용량 등을 고려한 순간 열부하 산정을 위한 여러 방법 중 우선적으로 CFD(Computational Fluid Dynamics)를 이용하였다. 순간 열부하 산정을 위한 해석 도구 선정에 있어서 다양한 유체 및 기체 전산 유체역학 Solver(Fluent, Open-FOAM, Blender)를 고려하였다. 공간 Mech를 수행하기 위한 도구로는 공개 소프트웨어 인 FreeFem++ 3.51-4 (http://www.freefem.org)를 이용하였다. 이 과정에서 일부 기체 (암모니아)의 농도를 난수로 변화시키는 기법을 적용하여 가상적으로 돈사의 환경을 Pseudo 시뮬레이션 하였다. 결과적으로 Fluent에 비하여 OpenFOAM을 이용하여 얻은 열유동의 방향(속도)과 크기 백터가 상대적으로 크게 나타났다. Fluent가 시계열 상에서 혼합 기체 물리량 변화를 무시할 수 있는 안정되고 균일한 환경에 적합하기 때문인 것으로 판단되었다. Blender의 경우 Lattice Boltzmann methods 과 Smoothed-particle hydrodynamics 방법을 이용한 유체/입자 동력학 모델링을 제공함에 있어 시각적 효과를 강조하는 기능에 중점을 두었다. Fluent와 Blender에서 제공하는 해석 연산 모듈의 정확성 검증을 위해선 공간 분해능을 높인 정밀 계측 시스템을 이용하여 검증할 필요가 있다. Open-FOAM를 이용한 열부하 분석 수행이 상대적으로 높은 절대값을 보이는 특성은 열부하 제어 시스템의 Overshoot를 유발할 가능성이 있으므로 이에 대한 해석 모델의 보정이 추가적으로 필요할 것이다. CFD의 한계인 시간 복잡도를 낮추고 상대적으로 높은 시계열 분해능을 확보할 경우 돈사 내 환기시스템에 맞는 소요 환기량 실시간 산정이 가능해지고 외부기상 및 돈사내부 복사열을 활용함과 동시에 돈군 순환에 상응하는 실시간 열부하 관리 시스템 도출이 가능할 것이다.