• 설비공학논문집
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• 제17권9호
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• pp.799-807
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• 2005

The flow characteristics and the heat transfer rate on a surface by the interaction of a pair of vortices are studied numerically. To analyze the common flow up produced by vortex generators in a rectangular channel flow, the pseudo-compressibility viscous method is introduced into the Reynolds-averaged Navier-Stokes equation for 3-dimensional unsteady, incompressible viscous flows. To predict turbulence characteristics, a two-layer $k-\varepsilon$ turbulence model is used on the flat plate 3-dimensional turbulence boundary The computational results predict accurately Reynolds stress, turbulent kinetic energy and flow field generated by the vortex generators. The numerical results, such as thermal boundary layers, skin friction characteristics and heat transfers, are also reasonably close to the experimental data.

• 한국지반환경공학회 논문집
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• 제10권2호
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• pp.61-68
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• 2009

본 논문은 수리학적 현장 주입시험 기간 동안 고려될 필요가 있는 수리역학적 상호작용에 따른 균열암반매질의 수리학적 거동에 대한 수치적 연구이다. 이러한 주입시험은 굴착정 내에 설치된 개구간(open hole section)을 따라 높은 압력을 가진 유량을 주입하며, 이를 통해 굴착정을 가로지르는 균열로부터 유량을 측정하는 것이다. 시간에 따라 변화되는 유량측정결과는 수리역학적 상호작용에 대한 분석 및 예측을 위해 개발된 수치모형의 현장 적용성을 평가하기 위해 사용되었다. 유량측정결과 전도성이 있는 균열들은 상호의존적인 균열망을 형성하며, 이로 인해 균열망을 구성하는 개별적인 균열요소들은 독립적인 시스템으로서 적절하게 모형화 될 수 없음을 보여주었다. 또한 간극수압이 굴착정 주위에 작용하는 최소주응력을 초과할 때 새로운 유체유입영역이 발생되며, 이러한 최소주응력보다 훨씬 큰 간극수압은 굴착정 주위의 균열들에 의해 유지될 수 있다는 것을 보여주었다. 본 연구에서 이러한 특성들이 자연 상태의 균열망의 구성형태에 따라 어떻게 영향을 미치게 되는지 이산 균열망 모형을 통해 수치적으로 분석되었다.

• 한국콘텐츠학회논문지
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• 제21권6호
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• pp.261-273
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• 2021

본 연구는 상담자 스트레스가 삶의 만족에 미치는 과정에서 상담자 자기돌봄을 통한 소진의 조절된 매개효과를 검증하기 위해 상담현장에서 근무하고 있는 상담자 416명의 응답 자료를 활용하여 모형을 분석하였다. 첫째, 상담자 스트레스는 소진을 매개로 삶의 만족에 영향을 미치는 것으로 나타났다. 둘째, 상담자 스트레스와 자기돌봄의 상호작용 효과는 유의하며, 자기돌봄 수준에 따라 스트레스와 소진 간의 관계가 달라지는 것으로 나타났다. 셋째, 상담자 스트레스는 소진을 거쳐 삶의 만족에 영향을 미치는 매개효과가 자기돌봄에 의해 조절되는 것으로 확인되었다. 본 연구결과는 상담자의 스트레스와 소진을 예방하고 완화하여 삶의 만족을 증진시키는 자기돌봄의 효과 검증을 통해, 상담자의 개인적·전문적 성장, 삶의 질 향상에 기여할 수 있는 자기돌봄 요인의 실증적인 근거를 마련했다는 데 의의가 있다.

• Earthquakes and Structures
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• 제24권1호
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• pp.65-79
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• 2023

A simplified analytical solution for seismic response of tunnel cross section in horizontally layered ground subjected to oblique incidence of SH wave is deduced in this paper. The proposed analytical solution consists of two main steps: free-field response in layered field and tunnel response. The free field responses of the layered ground are obtained by one-dimensional finite element method in time domain. The tunnel lining is treated as a thick-wall cylinder to calculate the tunnel response, which subject to free field stress. The analytical solutions are verified by comparing with the dynamic numerical results of two-dimensional ground-lining interaction analysis under earthquake in some common situations, which have a good agreement. Then, the appropriate range of the proposed analytical solution is analyzed, considering the height of the layered ground, the wavelength and incident angle of SH wave. Finally, by using the analytical solutions, the effects of the ground material, burial depth of the tunnel, and lining thickness and the slippage effect at the ground-lining interface on the seismic response of tunnels are investigated. The proposed solution could serve as a useful tool for seismic analysis and design of tunnels in layered ground.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.430-440
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• 2009

Top-Base Foundation(TBF) was developed in Japan as a factory made concrete product. It is actively used in 6,000 sites by the end of 1980s in Japan and applied for a domestic patent in 1985. It is a shallow foundation whose effectiveness is proven by many relevant researchers and engineers. TBF was introduced to Korea in 1991 and has been applied mainly to architectural structures to date. Currently, the effectiveness in bearing capacity and settlement of TBF is being underestimated for civil engineering structures. Characteristics of Top-Base Foundation studied in Japan and Korea is known as follows: (1) as concrete part and crushed stone behave together, they perform the function of rigid mat; (2) the conical part and pile part of TBF disperses load by interaction with the crushed stone; (3) by preventing lateral strain and differential settlement on lower ground, it improves bearing capacity and constrains settlement at the same time. In Korea, it is used mostly in clayey soft grounds. The formula of bearing capacity and settlement of TBF suggested in Japan give the values of the underestimated. bearing capacity while its settlement is overestimated in comparison with the values measured from the field loading test. Therefore, in this study, the stress delivery mechanism of Top-Base Foundation developed in Japan and Floating Top Base developed in Korea is investigated through numerical analysis and laboratory model test.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.39-47
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• 2002

Heat is always the root of stress acting upon the electronic package, regardless of the heat due to the device itself during operation or working under the adverse environment. Due to the significant mismatch in coefficient of thermal expansion (CTE) and the thermal conductivity (K) of the packaging components, on one hand intensive research has been conducted in order to enhance the device reliability by minimizing the mechanical stressing and deformation within the package. On the other hand the effectiveness of different thermal enhancements are pursued to dissipate the heat to avoid the overheating of the device. However, the interactions between the thermal-mechanical loading has not yet been address fully. in articular when the temperature gradient is considered within the package. To address the interactions between the thermal loading upon the mechanical stressing condition. coupled-field analysis is performed to account the interaction between the thermal and mechanical stress distribution. Furthermore, process induced defects are also incorporated into the analysis to determine the effects on thermal conducting path as well as the mechanical stress distribution. It is concluded that it feasible to consider the thermal gradient within the package accompanied with the mechanical analysis, and the subsequent effects of the inherent defects on the overall structural integrity of the package are discussed.

• Environmental Analysis Health and Toxicology
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• 제27권
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• pp.7.1-7.7
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• 2012

Objectives: Modafinil is a waking drug prescribed to narcolepsy patients, but its usage among healthy individuals is increasing to enhance their alertness or to mitigate fatigue. This study was conducted to investigate practical use and toxic effects on neuro-immune interaction of modafinil. Methods: This study reviewed the significance of psychoactive drugs, and discussed the benefits and risks of the application of modafinil, which seems to be ideal as an anti-psychotic or anti-fatigue agent. Results: Modafinil is known to have less or no adverse effects than those found in traditional psychostimulants such as amphetamine, methylphenidate or cocaine. It can be applied as an anti-psychotic or anti-fatigue agent. However, the waking mechanism of modafinil is yet to be fully revealed. Recent studies reported that modafinil may be subject to abuse and addiction. In addition prolonged sleeplessness induces stress responses and impairs immune function. Conclusions: Modafinil can be used by anyone, who wishes to work late, stay awake, enhance their cognitive reactions, or brighten their moods. Users may already be under a great level of stress, i.e. cancer patients or soldiers in a battle field. A psychoneuroimmunological approach is thus needed to investigate the multi-functional effects of modafinil.

• Advances in aircraft and spacecraft science
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• 제3권3호
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• pp.243-257
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• 2016

The increase of air traffic volume has brought an increasing amount of issues related to carbon and NOx emissions and noise pollution. Aircraft manufacturers are concentrating their efforts to develop technologies to increase aircraft efficiency and consequently to reduce pollutant discharge and noise emission. Ultra High By-Pass Ratio engine concepts provide reduction of fuel consumption and noise emission thanks to a decrease of the jet velocity exhausting from the engine nozzles. In order to keep same thrust, mass flow and therefore section of fan/nacelle diameter should be increased to compensate velocity reduction. Such feature will lead to close-coupled architectures for engine installation under the wing. A strong jet-wing interaction resulting in a change of turbulent mixing in the aeroacoustic field as well as noise enhancement due to reflection phenomena are therefore expected. On the other hand, pressure fluctuations on the wing as well as on the fuselage represent the forcing loads, which stress panels causing vibrations. Some of these vibrations are re-emitted in the aeroacoustic field as vibration noise, some of them are transmitted in the cockpit as interior noise. In the present work, the interaction between a jet and wing or fuselage is reproduced by a flat surface tangential to an incompressible jet at different radial distances from the nozzle axis. The change in the aerodynamic field due to the presence of the rigid plate was studied by hot wire anemometric measurements, which provided a characterization of mean and fluctuating velocity fields in the jet plume. Pressure fluctuations acting on the flat plate were studied by cavity-mounted microphones which provided point-wise measurements in stream-wise and spanwise directions. Statistical description of velocity and wall pressure fields are determined in terms of Fourier-domain quantities. Scaling laws for pressure auto-spectra and coherence functions are also presented.

• 부모자녀건강학회지
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• 제3권1호
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• pp.1-14
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• 2000

The Low Birth Weight infant birth rate in this country is a little more than 15 percent and is being increased. The survival rate of Low Birth Weight infant is over 90 percent and recently the rate runs is getting. However, because of the high risk of Low Birth Weight infant for handicap in growth, a preventive nursing intervention program for Low Birth Weight infant and their mother is considered to be necessary. Touch and massage, thus sensory stimulation has been considered to be important ensuring a normal growth of Low Birth Weight infant During the past decades sensory stimulation program has been used for premature and Low Birth Weight infants. Recently a study on the sensory stimulation for Low Birth Weight infants has bee n done in this country. Mother and infant relationship has a great influence on child's development. Especially, mother and infant interaction during one year after birth plays important role in child's social. affective and cognitive developments. But in the study of Low Birth Weight infants, the mother and infant interaction has been rare yet. However, there was no study effectiveness of the sensory stimulation on mother and infant interaction. In this respect, this study based on the importance of the nursing intervention, is intended to measure the effectiveness of the massage therapy in the aspects of weight, daily feeding amount, cortisolurine stress hormone and mother and infant interactions. This study has been conducted on the nonequivalent control group pretestposttest design in quasi experimental basis and Low Birth Weight infants from NICU of two Medical University Hospitals located in Taegu Metropolitan were selected in experimental group of 21 infants and control group of 20 infants. Data has been collected from May 1, 1999 to September 5, 2000. For the experimental group Field's sensory stimulation(tactile and kinesthetic stimulation) was applied 2 times a day for 10 days(10:00 - 11:00 hours in the morning and 19:00 - 20:00 in the afternoon) by nurse and mother. The electronic indicator scale (Cas Co. Korea) was used to measure infant's body weight. To determine urine cortisol concentration level under stress, rad immuno assay method was used. And to determine mother and infant interactions during feeding, tools developed by Kim Mi-Ye (1999) were used. Collected data were analyzed with SAS program using x-test, t-test, paired t-test and repeated measures ANOVA. Findings were as follows : 1. For the daily mean weight gain, the experimental group showed little higher than the control group, even though, there was no Statistically significant differences between two groups. 2. For the amount of daily mean feeding, the experimental group showed little higher than the control group, while there was no Statistically significant differences between two groups. 3. The level of wine cortisol concentration was increased in both groups, while no Statistical significance was shown between the two groups. 4. Mothers in experimental group were more likely to have higher mean scores in mother and infant interaction during feeding than mothers in the control group. Statistical significance was shown between the two groups(t= 5.78, P=.001). In conclusion, the massage therapy in this study showed with regard to even though through there was no statistically significance in the weight gain and urine stress hormone concentration. there was Statistical significantly higher in the mother and infant interaction during feeding. Based on the result of this study, it is considered that the massage therapy should be applied clinical practice and home to help a developmental growth and interaction of Low Birth Weight infants and mothers during the period of recovery.

• 한국해양공학회지
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• 제27권4호
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• pp.98-106
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• 2013

Seismic fragility curves for an offshore wind-turbine structure were obtained. The dynamic response of an offshore wind turbine was analyzed by considering the nonlinear behavior of layered soil and the added mass effect due to seawater. A pile-soil interaction effect was considered by using nonlinear p-y, t-z curves. In the analysis, the amplification effect of ground acceleration through layered soil was considered by applying ground motion to each of the soil layers. The vertical variation in ground motion was found by one-dimensional free-field analysis of ground soils. Fragility curves were determined by damage levels in terms of tower stress and nacelle displacements that were found from static pushover analysis of the wind-turbine structure.