• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.167-174
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• 2015

Purpose : The pre-treatment QA using Portal dosimetry for Volumetric Arc Therapy To analyze whether maintaining the reproducibility depending on various factors. Materials and Methods : Test was used for TrueBeam STx$^{TM}$ (Ver.1.5, Varian, USA). Varian Eclipse Treatment planning system(TPS) was used for planning with total of seven patients include head and neck cancer, lung cancer, prostate cancer, and cervical cancer was established for a Portal dosimetry QA plan. In order to measure these plans, Portal Dosimetry application (Ver.10) (Varian) and Portal Vision aS1000 Imager was used. Each Points of QA was determined by dividing, before and after morning treatment, and the after afternoon treatment ended (after 4 hours). Calibration of EPID(Dark field correction, Flood field correction, Dose normalization) was implemented before Every QA measure points. MLC initialize was implemented after each QA points and QA was retried. Also before QA measurements, Beam Ouput at the each of QA points was measured using the Water Phantom and Ionization chamber(IBA dosimetry, Germany). Results : The mean values of the Gamma pass rate(GPR, 3%, 3mm) for every patients between morning, afternoon and evening was 97.3%, 96.1%, 95.4% and the patient's showing maximum difference was 95.7%, 94.2% 93.7%. The mean value of GPR before and after EPID calibration were 95.94%, 96.01%. The mean value of Beam Output were 100.45%, 100.46%, 100.59% at each QA points. The mean value of GPR before and after MLC initialization were 95.83%, 96.40%. Conclusion : Maintain the reproducibility of the Portal Dosimetry as a VMAT QA tool required management of the various factors that can affect the dosimetry.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.319-329
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• 2009

Sediment release openings or pipes are installed in the flood control dam constructed to reduce flood damages, which are to allow water and sediments pass through the dam and to prevent flow blockage and sedimentation in the upstream area of the dam. The Hantan River Flood Control Dam (HRFCD) has been projected for flood damage reduction and sediment release openings and ecological passages are considered for the dam design. In this study, sediment deposition due to the construction of HRFCD was analyzed using the HEC-6 model and compared with the state before the dam construction with respect to the conditions of the annual mean daily discharge and annual discharge hydrograph. According to the numerical results, although downstream water levels were changed by the dam structure, the effects of bed changes were not propagated from the dam over 2 km upstream. Also, 2D numerical models of RMA2 and SED2D were used to predict bed changes in the upstream area with and without sediment release openings. Consequently, it is presented that sediment release openings decreased maximum deposition height in the upstream channel of the dam.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.277-291
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• 2020

Shield TBM is a tunnelling method that has a wider range of applications in the poor ground condition compared to conventional tunnels (Drill and Blast). Currently, a 13.3 m large-diameter slurry shield TBM is preparing for construction to pass under the Han River. Shield TBM is divided into slurry and EPB shield TBM, and management items during construction are different depending on each characteristic. In this paper, the equipment type, origin, application case and trouble case were analyzed for slurry shield TBM, which is mainly constructed in soft ground. In addition, 2D and 3D model tests were conducted on the condition of soil depth for the possibility of slurry leakage into front of the equipment, with appropriate chamber pressure. Based on this paper, it proposed to provide basic and reference data for proper excavation surface pressure and chamber pressure during construction of slurry shield TBM under soft ground conditions, and proposed measures to minimize stability and environmental decline due to slurry ejection.

• Fire Science and Engineering
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• v.13 no.4
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• pp.38-55
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• 1999

In order practically to use fire-defective glazing materials for the compartment wall where a fire-protection rating is mandated, there have been many trials internationally, This research focuses on a feasibility that, if certain water film covered all surface of glass, the glazing system can endure without breaking out under the compartment fire. First of all, a water film spray system was specially designed to wet the entire surface of the glass and also to have tiny small amount of water rebounded from the surface after emitted from nozzles. After this system has proven to have perfect performance, small-scale tests were done to find out if the water film covered glazing system react to the high temperature curve in a small furnace room. Finally, on basis of the obtained data, full-scale experiments were done so that water-film covered glazing system can pass the Korean Standard (KS) test for fire resistance, KS F2257.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.590-597
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• 1985

A recursive geometric adaptive control method to compensate for machining straightness error in the finished surface due to tool deflection and guideway error generated by end milling process is developed. The relationship between the tool deflection and the feedrate is modeled by a modified Taylor's tool life equation. Without a priori knowledge on the variations off cutting parameters, time varying parameters are then estimated by an exponentially windowed recursive least squares method with only post-process measurements of the straightness error. The location error is controlled by shifting the milling bed in the direction perpendicular to the finished surface and adding a certain amount of feedrate with respect to the tool deflection model before cutting. The waviness error is compensated by adjusting the feedrate during machining. Experimental results show that location error is controlled within a range of fixturing error of the bed on the guideway and that about 60% reduction in the waviness error can be achieved within a few steps of parameter adaption under wide operating ranges of cutting conditions even if the parameters do not converge to fixed values.

• Journal of Cadastre & Land InformatiX
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• v.47 no.2
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• pp.145-157
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• 2017

Currently, the height of ships that can pass under Busan Harbor Bridge is limited to 60m or shorter, so that large-sized ships of 60m or taller cannot use Busan Harbor international passenger terminal. Accordingly, this study has developed a service which measures continuously the change of bridge height by water level changes and provides such in real-time for safe bridge passage of large-sized ships of 60m or taller. The measurement system comprised of high-precision laser distance measurement device, GPS sensor, optical module, and damping structure is used to measure the bridge height change according to tide level changes, and the measured information is provided in real-time through cloud-based mobile app. Also, in order to secure objective bridge height data for changes to height limits and navigation supports, the observation data was analyzed and forecast model was drawn. As a result, it became an objective evidence to revise the passage height rules of the Busan Port Bridge from 60 meters to 63 meters.

• Geophysics and Geophysical Exploration
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• v.22 no.4
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• pp.177-185
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• 2019

Ground roll is a surface wave which is usually observed in the land seismic data. It is one of the typical coherent noise. During the reflection data processing, ground roll is removed because it is considered as noise. This removal process often causes the loss of reflection signals if the ground roll overlaps reflection signals. In this study, we look over Karhunen-Loeve Transform (KLT) and analyze its effects to suppress the ground roll appropriately while reducing the reflection loss. Numerical tests in homogeneous elastic media show that the ground roll has been properly rejected. However, the field data application reveals that there is no significant suppression of ground roll when compared to band-pass filtering. This can be considered that it is hard to calculate horizontally aligned gathers in the field data because the ground roll contains a wide range of frequency bands. On the contrary, the result of singular value decomposition (SVD) filtering shows that the ground roll has been significantly reduced. It is thought that the SVD filtering performs better in the ground roll suppression than KLT because it is easy to calculate the horizontally aligned gathers in the SVD filtering.

• The Journal of Industrial Distribution & Business
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• v.9 no.11
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• pp.39-54
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• 2018

Purpose - To success, in spite of deficient resources, a start-up company has to check various circumstances. Many researchers proposed different appraisal methods for technology commercialization. But everybody agrees Merrifield is the first one, who is a pioneer of an appraisal model of technology commercialization. After he proposed it, many researchers and field workers developed a more complicated model, which called a BMO model. In this research, considering the circumstances of start-ups that lack available resources, it proposes a new appraisal method for technology commercialization, which is named a weighted-BMO model. Research design, data, and methology - For the new BMO-model, it studied the preceding studies. And it found that the success factors for start-ups were correlated with technology commercialization. After comparing the success factors for technology commercialization of start-ups with BMO appraisal factor, it withdraws the net BMO appraisal model: which we are calling the weighted-BMO model. Results - This study found a few things. First, actually, the BMO appraisal factors related with the success factors of technology commercialization. Second, the weighted-BMO model, which included the entrepreneur ability factor, was more accurately estimated the success of technology-based start-ups than the BMO model. Third, it overcame the weakness of the BMO-model, which did not include quantitative factors. In addition to evaluating the feasibility of the BMO model, we also presented a strategy for the future direction. But, still, it included a few shortcomings, which we are calling the arbitrage of weighted value. Sometimes, the intentional weighted value can deliberate the different valuation. Conclusitons - Due to this study, the weighted-BMO model included appraisal factors related with the success factors of technology commercialization and the entrepreneur ability factor, and quantitative factors. When evaluating the combined score of the existing Merrified BMO components, 35 points of the first pass criterion accounted for 29.17% of the total score, and 80 points of the merit score of the second rank criterion were 66.67% Considering that the weighted sum is taken into account, the baseline score of the weighted summing method for each component of the modified BMO model is 2.92 points, which is 29.17% of the weighted sum total of 10 points. The evaluation score was 6.67 points, 66.67% of the weighted total score of 10 points.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.119-128
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• 1998

This paper describes a filtering algorithm which employs apriori information of SPECT lesion detectability potential for the filtering of degraded projection images prior to the backprojection reconstruction. In this algorithm, we determined m minimum detectable lesion sized(MDLSs) by assuming m object contrasts uniformly-chosen in the range of 0.0-1.0, based on a signal/noise model which provides the capability potential of SPECT in terms of physical factors. A best estimate of given projection image is attempted as a weighted combination of the subimages from m optimal filters whose design is focused on maximizing the local S/N ratios for the MDLS-lesions. These subimages show relatively larger resolution recovery effect and relatively smaller noise reduction effect with the decreased MDLS, and the weighting on each subimage was controlled by the difference between the subimage and the maximum-resolution-recovered projection image. The proposed filtering algoritym was tested on SPECT image reconstruction problems, and produced good results. Especially, this algorithm showed the adaptive effect that approximately averages the filter outputs in homogeneous areas and sensitively depends on each filter strength on contrast preserving/enhancing in textured lesion areas of the reconstructed image.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.593-593
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• 2012

본 연구는 화력 및 원자력 발전소로 취입된 냉각수(circulating and essential service water)가 복수기로부터 온배수 형태의 개수로 흐름으로 표층배수 될 경우 수온을 저감시키기 위해 주입하는 희석수(by-pass cooling water)와의 혼합효과의 효율성을 증대시키고, 불리한 수리현상을 야기하지 않으며, 경제적인 배수로 구조물을 고찰하기 위한 목적으로 시도되었다. 배수로 구조물 내 온배수와 희석수가 혼합되는 구간을 혼합지(mixing basin)라 하는데, 본 과업에서는 ${\bigcirc}{\bigcirc}$발전소의 배수로 구간 중 혼합지를 대상으로 FLOW-3D$^{(R)}$를 이용한 3차원 수치모형을 구축하고, 총 9개에 해당하는 각 대안별 현상을 분석하고 비교하였다. 각 대안들의 차이점은 배수로에 설치되는 보조구조물들의 형상과 배열 등이며, 복수기로부터 나오는 배출수의 수온은 $42^{\circ}C$, 희석수는 $35^{\circ}C$이고, 본 과업의 주요 관심대상 물리량은 유속과 온도이다. 배수로에 아무런 보조 구조물이 없는 형태인 기본 계획안을 검토한 결과, 평균 $3.31^{\circ}C$의 수온강하가 이루어졌으나, 우안 쪽으로 강한 흐름이 발생하여 수온의 좌우편차가 $4.61^{\circ}C$ 가량 발생하는 것으로 나타났다. 기본 계획안의 검토결과를 보완하기 위한 대안으로 연직 흐름의 소산을 위해 고안된 잠형 소파블록(baffle block) 설치안은 평균 $3.06^{\circ}C$의 수온강하가 이루어지고 $4.44^{\circ}C$의 수온 좌우편차가 발생했다. 지그재그(zigzag) 형태의 흐름을 만들어 혼합효과를 올리기 위한 미로형 수제(labyrinth groin) 설치안은 평균 $5.33^{\circ}C$의 수온강하가 이루어지고, $1.43^{\circ}C$의 수온 좌우편차를 보여줘 검토했던 대안들 중 가장 좋은 결과를 보여주었다. V자 배열 소파블럭(deformed block) 설치안은 연직 및 수평방향의 소산을 기대했으나 평균 $3.00^{\circ}C$의 수온 강하와 $4.41^{\circ}C$의 수온 좌우편차를 나타냈다. 벤츄리(Venturi) 형태의 흐름을 발생시키기 위한 병목형(bottleneck) 수로안은 평균 $3.18^{\circ}C$의 수온강하와 $3.94^{\circ}C$의 수온 좌우편차, 흐름의 소산과 흐름방향을 변화시키기 위한 와형 수제(swirl groin) 설치안은 평균 $2.24^{\circ}C$의 수온강하와 $1.48^{\circ}C$의 수온좌우편차, 우안 흐름을 지연시키기 위한 물방석(water cushion) 수로안은 평균 $3.03^{\circ}C$의 수온강하와 $4.50^{\circ}C$의 수온 좌우편차, 우안의 흐름을 좌안으로 보내기 위한 분사형(injector) 수로안은 평균 $3.13^{\circ}C$의 수온강하와 $4.45^{\circ}C$의 수온 좌우편차, 우안의 흐름을 막기 위한 외팔형 수제(cantilever groin) 설치안은 평균 $3.11^{\circ}C$의 수온강하와 $3.02^{\circ}C$의 수온 좌우편차가 발생하는 것으로 나타났다.