• 해양환경안전학회지
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• 제26권3호
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• pp.242-253
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• 2020

This study examined the ef ects of freshwater discharge by artificial dikes from the Kanwol and Bunam lakes on the dynamics in the Chunsu Bay, Yellow Sea, Korea, during the summer season based on three-dimensional numerical modeling experiments. Model performances were evaluated in terms of skill scores for tidal elevation, velocity, temperature, and salinity and these scores mostly exceeded 90 %. The variability in residual currents before and after the freshwater discharge was examined. The large amount of lake water discharge through artificial dikes may result in a dramatically changed density field in the Chunsu Bay, leading to an estuarine circulation system. The density-driven current formed as a result of the freshwater inflow through the artificial dikes (Kanwol/Bunam) caused a partial change in the tidal circulation and a change in the scale and location of paired residual eddies. The stratification formed by strengthened static stability following the freshwater discharge led to a dramatic increase in the Richardson number and lasted for a few weeks. The strong stratification suppressed the vertical flux and inhibited surface aerated water mixing with bottom water. This phenomenon would have direct and indirect impacts on the marine environment such as hypoxia/anoxia formation at the bottom.

• 디지털융복합연구
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• 제15권11호
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• pp.209-220
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• 2017

본 연구는 조직 불확실성을 낮추고, 핵심 역량을 높이기 위한 조직의 주요 방안인 임파워링 리더십과 개인지향 및 조직지향 조직시민행동과의 영향관계를 실증 분석하고, 조직 내에서 임파워링 리더십이 발현되는 과정을 밝히고자 한다. 이러한 변수간의 관계를 밝히고자, 문헌연구를 통해 연구 모형 및 가설을 설정하였고, 대구 경북 지역의 제조업 종사자를 중심으로 설문조사를 통해, 총 346부의 설문지를 활용하여 실증분석을 실시하였다. 연구 결과, 임파워링 리더십은 개인지향 조직시민행동과 조직 지향 조식시민행도에 유의미한 영향을 미치는 것을 확인하였다, 또한, 셀프리더십이 임파워링 리더십과 조직시민행동의 관계를 매개하는 것으로 나타났다. 이러한 연구 결과는 조직내의 임파워링 리더십을 정착시키며, 추후 보다 다양한 표본를 활용한다며, 조직 유효성을 높이는 방안이 될 것이다.

• Structural Engineering and Mechanics
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• 제65권5호
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• pp.573-585
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• 2018

This article presents strain gradient elasticity-based procedures for static bending, free vibration and buckling analyses of functionally graded rectangular micro-plates. The developed method allows consideration of smooth spatial variations of length scale parameters of strain gradient elasticity. Governing partial differential equations and boundary conditions are derived by following the variational approach and applying Hamilton's principle. Displacement field is expressed in a unified way to produce numerical results in accordance with Kirchhoff, Mindlin, and third order shear deformation theories. All material properties, including the length scale parameters, are assumed to be functions of the plate thickness coordinate in the derivations. Developed equations are solved numerically by means of differential quadrature method. Proposed procedures are verified through comparisons made to the results available in the literature for certain limiting cases. Further numerical results are provided to illustrate the effects of material and geometric parameters on bending, free vibrations, and buckling. The results generated by Kirchhoff and third order shear deformation theories are in very good agreement, whereas Mindlin plate theory slightly overestimates static deflection and underestimates natural frequency. A rise in the length scale parameter ratio, which identifies the degree of spatial variations, leads to a drop in dimensionless maximum deflection, and increases in dimensionless vibration frequency and buckling load. Size effect is shown to play a more significant role as the plate thickness becomes smaller compared to the length scale parameter. Numerical results indicate that consideration of length scale parameter variation is required for accurate modelling of graded rectangular micro-plates.

• Journal of Computational Design and Engineering
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• 제3권4호
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• pp.349-362
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• 2016

The numerical solutions of unsteady hydromagnetic natural convection Couette flow of a viscous, incompressible and electrically conducting fluid between the two vertical parallel plates in the presence of thermal radiation, thermal diffusion and diffusion thermo are obtained here. The fundamental dimensionless governing coupled linear partial differential equations for impulsive movement and uniformly accelerated movement of the plate were solved by an efficient Finite Element Method. Computations were performed for a wide range of the governing flow parameters, viz., Thermal diffusion (Soret) and Diffusion thermo (Dufour) parameters, Magnetic field parameter, Prandtl number, Thermal radiation and Schmidt number. The effects of these flow parameters on the velocity (u), temperature (${\theta}$) and Concentration (${\phi}$) are shown graphically. Also the effects of these pertinent parameters on the skin-friction, the rate of heat and mass transfer are obtained and discussed numerically through tabular forms. These are in good agreement with earlier reported studies. Analysis indicates that the fluid velocity is an increasing function of Grashof numbers for heat and mass transfer, Soret and Dufour numbers whereas the Magnetic parameter, Thermal radiation parameter, Prandtl number and Schmidt number lead to reduction of the velocity profiles. Also, it is noticed that the rate of heat transfer coefficient and temperature profiles increase with decrease in the thermal radiation parameter and Prandtl number, whereas the reverse effect is observed with increase of Dufour number. Further, the concentration profiles increase with increase in the Soret number whereas reverse effect is seen by increasing the values of the Schmidt number.

• 한국의류산업학회지
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• 제17권5호
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• pp.781-792
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• 2015

This study aims to develop a spring/fall motorcycle jacket for quick service transporter. Depending on the results of the previous research, this study produced the tested jacket which was improved in material, pattern, and design. For the tested jacket, 100% polyester fabric excellent in strength, durability and abrasion-resistance was selected as a major material, and Cordura was used as a partial material to improve the strength and abrasion-resistance of the sleeve side lines, elbow and shoulder areas. The retro-reflection material was applied partially in order to improve visibility of the jacket in the night or in a dark place. A total of 7 pockets were composed in the jacket for the sufficient storage spaces. The functional design elements such as the 2-way zipper and the placket at the center front, the action pleats at the upper part of back armholes, the pit-zip at armpit were applied. In addition, the sleeve pattern was bent with the shape of elbow curvature in time of driving and the back length of the jacket was lengthened 4cm. As a result of the appearance assessment, there was a significant difference from the existing jacket in all items but chest size, shoulder width, cuffs circumference, and jacket hemline circumference. In motion adaptability and field activity appropriateness assessments, the assessment grade for all items was found to be commonly higher than that of the existing jacket, and thus, the tested jacket was assessed to be suitable for a motorcycle jacket design for the quick service transporters.

• Earthquakes and Structures
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• 제11권2호
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• pp.327-346
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• 2016

The 2012 Emilia (Italy) earthquakes struck a highly industrialized area including several thousands of industrial prefabricated buildings. Due to the lack of specific design and detailing for earthquake resistance, precast reinforced concrete (RC) buildings suffered from severe damages and even partial or total collapses in many cases. The present study reports a data inventory of damages from field survey on prefabricated buildings. The damage database concerns more than 1400 buildings (about 30% of the total precast building stock in the struck region). Making use of the available shakemaps of the two mainshocks, damage distributions were related with distance from the nearest epicentre and corresponding Pseudo-Spectral Acceleration for a period of 1 second (PSA at 1 s) or Peak Ground Acceleration (PGA). It was found that about 90% of the severely damaged to collapsed buildings included into the database stay within 16 km from the epicentre and experienced a PSA larger than 0.12 g. Moreover, 90% of slightly to moderately damaged buildings are located at less than 25 km from the epicentre and were affected by a PSA larger than 0.06 g. Nevertheless, the undamaged buildings examined are almost uniformly distributed over the struck region and 10% of them suffered a PSA not lower than 0.19g. The damage distributions in terms of the maximum experienced PGA show a sudden increase for $PGA{\geq}0.28g$. In this PGA interval, 442 buildings were collected in the database; 55% of them suffered severe damages up to collapse, 32% reported slight to moderate damages, whereas the remaining 13% resulted undamaged.

• Radiation Oncology Journal
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• 제33권4호
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• pp.294-300
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• 2015

Purpose: To evaluate survival rates and prognostic factors related to treatment outcomes after bladder preserving therapy including transurethral resection of bladder tumor, radiotherapy (RT) with or without concurrent chemotherapy in bladder cancer with a curative intent. Materials and Methods: We retrospectively studied 50 bladder cancer patients treated with bladder-preserving therapy at Keimyung University Dongsan Medical Center from January 1999 to December 2010. Age ranged from 46 to 89 years (median, 71.5 years). Bladder cancer was the American Joint Committee on Cancer (AJCC) stage II, III, and IV in 9, 27, and 14 patients, respectively. Thirty patients were treated with concurrent chemoradiotherapy (CCRT) and 20 patients with RT alone. Nine patients received chemotherapy prior to CCRT or RT alone. Radiation was delivered with a four-field box technique (median, 63 Gy; range, 48.6 to 70.2 Gy). The follow-up periods ranged from 2 to 169 months (median, 34 months). Results: Thirty patients (60%) showed complete response and 13 (26%) a partial response. All patients could have their own bladder preserved. Five-year overall survival (OS) rate was 37.2%, and the 5-year disease-free survival (DFS) rate was 30.2%. In multivariate analysis, tumor grade and CCRT were statistically significant in OS. Conclusion: Tumor grade was a significant prognostic factor related to OS. CCRT is also considered to improve survival outcomes. Further multi-institutional studies are needed to elucidate the impact of RT in bladder cancer.

• 한국환경보건학회지
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• 제38권5호
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• pp.407-414
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• 2012

Objectives: This study was performed to assess based on field investigation the distribution characteristics of airborne fungi in an area of Seongdong-gu, Seoul. Methods: Three sites, a living area, forest and traffic site, were selected for evaluation of monthly level of outdoor airborne fungi. An on-site survey was executed between January 2009 and December 2009. During the experimental period, air sampling was performed every month in the afternoon (2:00 pm-5:00 pm) using a cascade impactor. Results: Outdoor airborne fungi measured in Seoul, Korea over one year showed a concentration range from 850CFU $m^{-3}$ to 15,200CFU $m^{-3}$. The mean respirable fraction of outdoor airborne fungi was 67% compared to total concentration. Regardless of measurement site, there was no significant concentration difference in outdoor airborne fungi between periods of yellow dust and non-yellow dust (p>0.05). There was no significant correlation relationship between outdoor airborne fungi and atmospheric factors such as temperature and relative humidity. The predominant genera of airborne fungi identified were Aspergillus, Cladosporium, Paecilomyces and Penicillium. Conclusion: Monthly levels of outdoor airborne fungi were highest in April and November and lowest in August. In seasonal concentration distribution, the autumn showed the highest level of outdoor airborne fungi, followed by spring, summer and winter. In regional concentration distribution, the highest level of outdoor airborne fungi was generally found in the forest, followed by the living area and traffic site.

• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.594-601
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• 2014

Rare-earth (RE) nitrides can be used as magnetocaloric materials in low temperature. They exhibit ferromagnetism and have Curie temperature in the region from 6 to 70 K. In this study, Holmium nitride (HoN) nano particles were prepared through plasma arc discharge technique and their magnetocaloric properties were studied. Nitrogen gas ($N_2$) was employed as an active element for arc discharge between two electrodes maintained at a constant current. Also, it played an important role not only as a reducing agent but also as an inevitable source of excited nitrogen molecules and nitrogen ions for the formation of HoN phase. Partial pressure of $N_2$ was systematically varied from 0 to 28,000 Pa in order to obtain single phase of HoN with minimal impurities. Magnetic entropy change (${\Delta}S_m$) was calculated with data set measured by PPMS (Physical Property Measurement System). The as-synthesized HoN particles have shown a magnetic entropy change ${\Delta}S_m$) of 27.5 J/kgK in applied field of 50,000 Oe at 14.2 K thereby demonstrating its ability to be applied as an effective magnetic refrigerant towards the re-liquefaction of hydrogen.

• 한국콘텐츠학회논문지
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• 제17권6호
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• pp.86-97
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• 2017

본 연구는 아르바이트의 업무자율성과 진로의식성숙의 관계에서 업무만족도의 매개효과를 검토하여 고등학생의 진로의식성숙을 향상시킬 수 있는 실천적 방안을 모색하고자 하였다. 조사대상은 아르바이트 경험이 있는 고등학생 849명으로 연구결과는 다음과 같다. 첫째, 업무자율성, 업무만족도, 진로의식성숙은 전반적으로 남학생보다 여학생이, 교육포부에 따라서는 고졸 희망학생이 전문대졸, 대졸이상 학생보다 더 높았다. 둘째, 아르바이트 업무자율성은 성별과 교육포부에 따라 진로의식성숙에 정적(+)인 영향을 미쳤다. 셋째, 업무만족도는 아르바이트 업무자율성과 진로의식성숙의 관계에서 부분매개 하였으며, Sobel test 결과 업무만족도의 매개효과는 유의한 것으로 나타났다. 이러한 결과는 아르바이트를 통한 진로의식성숙을 위해 청소년들에게 일의 주체로서 적극적으로 참여할 수 있는 기회를 현장에서 부여해야 함을 시사한다. 또한 고용주들은 청소년 직업교육 협조자 역할을 인식할 필요가 있으며, 학교와 지역사회는 질 높은 아르바이트를 통해 청소년들이 진로의식을 높일 수 있도록 아르바이트 진입경로를 공식화 할 수 있는 지원체계를 마련할 필요가 있다.