• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.387-394
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• 2010

The theoretical calculations for $B_nH_n$, $B_nH_{n+1}$, $B_nH_{n+2}$ (n = 3-6) have been considered at the B3LYP level of theory with the 6-311G$^*$ basis set. The optimized geometries, harmonic vibrational frequencies, and binding energies are evaluated to elucidate the thermodynamic stability and spectroscopic properties. The harmonic vibrational frequencies for the molecules considered in this study show all real numbers implying true minima and the binding energies are corrected using zero-point vibrational energies (ZPVE). The binding energies and average energies due to increasing of BH monomer are predicted.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.501-509
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• 2008

It is very important in designing civil engineering structures that the quantification of geological informations must be carried out in terms of importance. In this study, the geological informations are quantified and evaluated using analytic hierarchy process (AHP). A professional group was organized with 30 people in the field of civil engineering, transport, and geology. On the assumption that the civil engineering structure is linear such as highway or railroad, a survey of the group in terms of geological and hydro-geological elements has found that the hierarchy structure is composed of four levels. And fault structure is a primary factor which causes the stability of a linear civil engineering structure. The importance of geological items are arranged with fault (0.456), foliation/bedding plane(0.l65), lineation(0.144), ground water(0.124), and rock type(0.111).

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.21-28
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• 2022

The TMD has a simple structure than other vibration control devices and shows excellent control performance for the simple harmonic vibration generated in the structure. However, the vibration control range is narrower than other control devices, making it vulnerable to vibration cycles caused by unexpected external loads. The ETMD developed in this study consisted of Mass with electromagnets. Therefore when supplying a current, the magnetic field is formed to increase the friction force with the friction plate, thereby instantaneously controlling the behavior of the Mass. The experiment was conducted to compare the control performance of the control device by installing the ETMD developed for control performance evaluation in the center of the model simple beam bridge to forced excitation at 3.02 Hz where the maximum bending displacement occurs. As a result of the experiment, ETMD exhibited excellent control performance with a maximum bending displacement attenuation rate of 57.51%.

• Journal of Korea Multimedia Society
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• v.13 no.11
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• pp.1657-1666
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• 2010

Underwater wireless sensor networks (UWSN) need stable efficient data transmission methods because of environmental characteristics such as limited energy resource, limited communication bandwidth, variable propagation delay and so on. In this paper, we explain an enhanced hybrid transmission method that uses a hexagon tessellation with an ideal cell size in a two-dimensional underwater wireless sensor network model (2D) that consists of fixed position sensors on the bottom of the ocean. We also propose an energy efficient sensing and communication coverage method for effective data transmission in a three-dimensional underwater wireless sensor network model (3D) that equips anchored sensors on the bottom of the ocean. Our simulation results show that proposed methods are more energy efficient than the existing methods for each model.

• Journal of Korea Port Economic Association
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• v.28 no.4
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• pp.59-77
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• 2012

Inland transportation system has been improving inefficiencies and structural problems due to excess of supply. Therefore, inland transportation market needs to reform its regional logistics structure in order to increase its competitiveness. To improve the solution, the research studied efficiencies and productivity of inland transportation systems in regions. In order to obtain specific facts, each cities' five years of (2005-2009) balanced panel data on inland transportation system has been studied. According to CCR and BCC analysis, Ul-San has been evaluated as the most efficient DMU during 2005-2008. In addition, in 2009, Seoul was the most efficient DMU. Also, according to Window analysis, Gwan-Ju and Gwangwon-do scored 0.062. Therefore, they were estimated as stable DMUs. According to Malmquist productivity analysis, average productivity indexes of four terms of Chungcheongnam-do and Chungcheongbuk-do haves been increased to 6.6% and 7.3%. I hope this study contributes to the improvement of regional inland transportation system.

• Composites Research
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• v.24 no.1
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• pp.37-44
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• 2011

In this paper, Particle Swarm Optimization(PSO) is applied to the design of the Frequency Selective Surface(FSS) and residual stresses of hybrid radome is predicted. An equivalent circuit model with Square Loops arrays was derived and then PSO was applied for acquiring the optimized geometrical parameters with proper resonant frequency. Residual stresses occur in the FSS embedded composite structures after cocuring and have a great influence on the strength of the FSS embedded composite structures. They also effect transmission quality because of delamination. Therefore, the thermal residual stresses of FSS embedded composite structures were analyzed using finite element analysis with considering the effects of FSS pattern, and composite stacking sequence.

• Journal of the Korean GEO-environmental Society
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• v.11 no.10
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• pp.15-24
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• 2010

In the case of underground power utilities pipe such as circular pipe, the most difficult problem is low compaction efficiency of the bottom of pipe inducing the failure of utilities. To overcome this problem, various studies have been performed and one of these is CLSM(Controlled Low Strength Materials) accelerated flow ability. But underground power utilities pipe backfill materials is also needed to have good thermal property that can dissipate the heat as rapidly as it is generated. So, in this study, we performed thermal resistancy test for various materials such as sand, weathered soil, clay and mixed soil to analyze the thermal characteristics of CLSM(Controlled Low Strength Materials) with accelerated flow ability for various conditions(water content, unit weight, void ratio, curing time) and to evaluate the applicability for backfill material of underground power utilities pipe. The test results of 16 specimens for thermal resistancy test showed good thermal property that maintained below $85^{\circ}C\;cm/W$.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.149-149
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• 2020

하천에서 물 흐름이 보와 댐과 같은 수공구조물을 지날 때 일반적으로 흐름상태에 다양하고 급진적인 변화가 발생한다. 특히 흐름이 구조물을 지나면서 사류(supercritical flow)로 변하고 다시 상류(subcritical flow)로 복원되면서 일어나는 도수(hydraulic jump) 현상은 수위의 급변화, 흐름 에너지 소산, 변동성이 강한 압력 분포 등이 특징이다. 이러한 흐름 특성들은 보나 여수로와 같은 수공구조물 자체의 성능뿐만 아니라 이들 수공구조물의 하류에서 발생하는 국부세굴로 인해 구조물의 안정성에 부정적인 영향을 줄 수 있다. 따라서 수공구조물을 설계할 때는 이들 구조물을 통과하는 흐름의 비정상 난류 흐름 특성을 정확하게 해석하여 반영하여야 한다. 이 연구에서는 k-omega SST 난류 모형과 자유수면의 급격한 변동을 해석하기 위한 하이브리드-VOF(hybrid volume of fluid)기법을 이용하여 도수현상을 수치적으로 재현하고자 한다. 기존 CFD(computational fluid Dynamics) 모델링에서는 자유수면 변동의 영향을 고려하기 위해 VOF 기법을 많이 사용하였다. 하지면 전통적인 VOF 기법은 다상흐름(multiphase flow)을 오직 부피분율(volume fraction)의 함수로만 고려하며 모의함으로써 강한 수면변동뿐만 아니라 공기연행(air entrainment)를 동반하는 난류 흐름을 모의하는데는 한계가 있다. 이 연구에서 이용하는 Eulerian 기법인 하이브리드 VOF 기법은 물과 공기의 각 상에 대하여 흐름 특성들을 개별적으로 계산하기 때문에 공기연행을 포함한 급변류 흐름에서 전통적인 VOF 기법보다 적용성이 우수하다. 이와 같은 난류모형과 자유수면 포착기법을 이용하여 3차원 비정상 난류 흐름 수치모형을 구축하여 수공구조물 주변에서 발생하는 강한 공기연행과 난류 특성를 보이는 급변류를 수치적으로 재현한다. 이 연구는 계산된 수치해석 결과를 기존 수리실험 결과와 비교하여 수치모형의 적용성을 평가하고 도수 현상에서 발생하는 독특한 흐름 특성을 제시한다.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.281-293
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• 2021

Patients who went through maxillectomy can have severely impaired swallowing, mastication, and pronunciation functions because of palatal defects. Leakage occurs through the nasal cavity while eating, chewing becomes difficult due to the loss of teeth and alveolar ridges, and oral and nasal passages are not separated, leading to hyper-nasal sound, and significantly reducing the quality of life. To prosthetically reconstruct the defect, the weight of the obturator should be reduced as much as possible to minimize dropout because of gravity, and the bulb of the obturator should be properly extended into the defect to get additional retention and stability. In this case of a partially edentulous patient who underwent additional maxillary resection because of tumor recurrence, a metal framework was designed by applying the basic design principles of removable partial dentures. An obturator with improved retention, stability, and support was fabricated through functional impressions. The patient was satisfied with the improved facial expression, mastication, swallowing, and pronunciation, and showed stable occlusion and oral hygiene management during the follow-up period.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.117-122
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• 2006

In the geophysical monitoring to understand the change of subsurface material properties with time, the time-invariant static subsurface model is commonly adopted to reconstruct a time-lapse image. This assumption of static model, however, can be invalid particularly when fluid migrates very quickly in highly permeable medium in the brine injection experiment. In such case, the resultant subsurface images may be severely distorted. In order to alleviate this problem, we develop a new least-squares inversion algorithm under the assumption that the subsurface model will change continuously in time. Instead of sampling a time-space model into numerous space models with a regular time interval, a few reference models in space domain at different times pre-selected are used to describe the subsurface structure continuously changing in time; the material property at a certain space coordinate are assumed to change linearly in time. Consequently, finding a space-time model can be simplified into obtaining several reference space models. In order to stabilize iterative inversion and to calculate meaningful subsurface images varying with time, the regularization along time axis is introduced assuming that the subsurface model will not change significantly during the data acquisition. The performance of the proposed algorithm is demonstrated by the numerical experiments using the synthetic data of crosshole dc resistivity tomography.