자동차 고급화 추세에 따라 소비자의 차량 실내 환경에 대한 관심이 증가함에 따라 자동차의 기본적 성능뿐만 아니라 실내 쾌적성 향상에 관심이 증대되고 있다. 또한 자동차 실내 쾌적성에 대한 연구는 운전자에게 만족을 제공하 는데 그치지 않고, 운전자의 불쾌지수 및 스트레스를 낮추어서 교통사고의 위험을 줄이는데 기여할 수 있기 때문에 매우 중요한 연구 주제이다. 따라서 본 연구에서는 운전자의 뇌파측정을 통해 통풍시트의 온도변화에 따른 쾌적감 변화와 쾌적온도를 알아보고, 온도변화에 따른 남녀간 쾌적감에 대한 차이를 탐색하고자 하였다. 연구결과 첫째 통풍시 트의 온도가 22℃, 25℃, 28℃에서 각각의 실험군을 비교한 결과 28℃보다 25℃에서 통계적으로 유의하게 쾌적감이 더 높게 나타났다. 둘째 통풍시트 온도 변화에 따른 남녀간 쾌적감에 대한 실험결과 남성과 여성이 온도에 따라 느끼는 쾌적감은 통계적으로 유의한 차가 없는 것으로 나타났다. 향후 자동차의 실내온도와 통풍시트의 온도 변화에 따른 운전자의 쾌적감 변화를 파악하여 상관관계를 분석한다면, 운전자의 쾌적성을 확보하여 휴먼에러로 인한 교통사고를 낮출수 있을 뿐만 아니라 자동차의 전기에너지의 사용량을 줄일 수 있을 것이다.

This study is aimed to find out whether there is difference in the physiological change of a human body according to the illumination and color of interior space or not and to specify the effect of the condition of illumination and color, respectively on the attention. In order to do so, White and Green were selected for colors and 4,000k, 5,000k, and 6000k were done for color temperature, and then attention was identified. Examining the results, the more color temperature increased, the more attention improved (P < 0.05), and in the case of EEG, α wave decreased while performing the task of attention (P < 0.01), and β wave decreased more in Green than White in color condition, and it increased more in 4,000k than 5,000k and 6,000k (p < 0.05) in color temperature condition. To sum up, color condition didn't contribute to the attention much, in the case of color temperature, when it is 6,000k, it is judged that it helped to improve attention. It is considered that relaxation contributed to improving attention, as β wave and sympathetic nerve decreased in 6,000k (p < 0.05). It is judged that the relaxation of tensions which happened due to a beta wave and the reduction of sympathetic nervous system activity in 6,000k, a condition of high color temperature, contributed to the improvement of concentration. In further researches, it is intended that a test will be conducted for the subjects of different ages, and the correlation between color temperature and color stimulation and the influence of them on human body would be observed in subdivided, various test conditions through various color temperature and color stimulation.

The purpose of this study was to explore olfactory sensitivity of odors from injection molding processing. To do this, the experiment was carried out in an injection molding factory, and participants were exposed to the environment where odor-substances (Formaldehyde, Benzene, Toluene, Ethylbenzene, Xylene, Styrene) exist. In addition, we used the subjective scale using semantic adjectives as an olfactory sensitivity. As a result, the assessment structure of olfactory sensitivity was composed of eight factors (irritant, thermal, tense, unique, like-dislike, active, stable, masculine), and the main factor which was irritant characteristics explained 20% of the total olfactory sensibility. These results suggested that odors from injection molding processing would cause more negative emotional responses than the flavor which is mainly used in olfactory sensitivity. This study, as a basic study of the improvement in a factory environment for the efficiency of work, has limits in that it was conducted to the extent of identifying the olfactory sensitivity structure of those who were at a laboratory and who were exposed to the environment of odor substance induced in the injection molding processing. Therefore, for the method of removing malodorous substance, the effect of materials which can neutralize it, and the comparison of a direct performance in the environment where negative sensitivity structure exists, a series of studies which aim to improve the environment of injection molding factories, such as performance assessment in the environment of a factory and an office need to be conducted. It is expected that when these studies are put together, the improvement guidelines will be provided as a type that can maximize the effectiveness of work in the factory environment where injection molding processing is done.

As contemporary society has become more complicated, specialized, and segmented, people are experiencing more diverse types of stress. In particular, while several factors associated with job stress have been examined among nurses, who belong to a professional group, the existing research has made no quantitative assessments of stress that reflect temporal differences in individuals. Therefore, the aim of this study is to understand the effects of job stress on alpha-amylase with regard to the working hours of nurses, to assess the variations in jobs stress over time, and provide basic data to improve the quality of nursing services. Ninety nurses working in three shifts in general, emergency, and intensive care wards of a university hospital in D City participated in this study. Salivary alpha-amylase (SAA) was extracted and analyzed at two-hour intervals from 07:00 to 15:00 from nurses on the day shift and from 23:00 to 07:00 from those working the night shift. The SAA level was highest between 23:00 and 01:00 for nurses in general wards (mean±S.D. 39.00±14.88) and between 11:00 and 13:00 for those in both intensive care units and emergency wards (mean ± S.D. 67.50 ± 62.93 and mean ± S.D. 39.67±35.96, respectively). The characteristic variation in SAA was significant between 23:00 and 01:00 (p < 0.01) and for those in their fifties or older (p < 0.01). The activation ratio of alpha-amylase, a stress reactant, showed an increase when the sympathetic nervous system was activated by mental stress; in addition, job stress was manifested with the effect of awakening at different time segments and at different ages among the nurses. With the aim of raising the level of service based on the nurses maintaining their mental health, it is necessary to focus sharply on the time segment for critical control and to conduct repetitive studies to determine the divisions of eustress critical values as well as to expand the population.

It is important to understand psychological and physiological responses of occupants who seated in a chair in order to shape a comfortable indoor official environment. So it is needed to find out optimal seated conditions. The purpose of this study was to explore optimal condition of seat air conditioning control based on psychological or subjective responses (perceived temperature and comfort sensation) and physiological responses (heartrate variability; HRV). To do this, experimental conditions were designed by the difference of indoor temperature and seat air conditioning temperature. In the experiment 1, seven experimental conditions were designed with one control condition which was not used seat air conditioning system, and six experimental conditions which the difference of indoor temperature and seat air conditioning temperature (-1℃～-6℃). In the experiment 2, four experimental conditions were designed with one control condition and three experimental conditions (-3℃～-5℃). In addition, participants’ psychological or subjective response was measured by CSV (comfort sensation vote) and PTS (perceived temperature sensitivity) as a psychological or subjective response, and heartrate variability was measured as a physiological response. As a result, in the experiment 1, it was reported that the optimal conditions of seat air conditioning control based on participants’ psychological or subjective comfort were from -3℃ to -5℃ experimental conditions. In addition, in the experiment 2, it was reported that the optimal condition of seat air conditioning control based on participants’ physiological comfort was -4℃ experimental condition. These results suggested that seat air conditioning could affected to comfort sensation of occupants in an appropriate range, rather than unconditionally.

복잡한 연료실 내의 유동현상을 난류모형을 적용하여 해석하였다. 적용한 모형은 k-ε, k-Ω, spalart-allmaras, reynolds stress이고, 연로실내의 격자는 혼합격자(hybrid grid) 이다. 속도벡터, 압력분포, 반복계산(iteration)에 의한 잔류치(residual), 동력학적 양정(dynamic head) 등을 모사하였다. 4개의 난류모형을 연료실 유동에 적용하였다. 3차원 수치실험에 앞서, 수치검증을 위하여 2차원 물체 주위의 점성유동을 k-ε 난류모형을 적용하여 모사하였고 항력계수를 비교하였다.

장애물이 있는 배관속의 점성유동을 다양한 난류모형을 적용하여 해석하였다. 적용한 난류모형은 k-ε, k-Ω, Spalart-Allmaras, Reynolds stress 이고, 배관내의 격자는 구조격자(structured grid) 이다. 속도벡터, 압력분포 반복계산(iteration)에 의한 잔류치(residual), 양정(dynamic head) 등을 모사하였다. 4개의 난류모형을 배관유동에 적용하였고 상용 프로그램을 사용하여 해석을 수행하였다.

선미파의 점성 상호작용과 수중고속선의 sub-breaking 현상을 해석하기 위하여 자유표면 유통을 수치적으로 시뮬레이션하였다. Navier-Stokes 방정식을 풀었으며 유한차분법, 물체적합좌표계, 벽법칙, 삼중격자법을 적용하였다. S-103 모형을 대상으로 준쇄파의 수치결과를 실험과 비교하였고 준쇄파 발생조건을 수중 고속선인 3차원 회전체에 대해 적용하였다. 준쇄파 해석결과에 의하면 M/Us 구배가 잠김 깊이에 영향을 미치고 있음을 알 수 있었다. 또한 선수파가 박리에 영향을 미쳐 선미파를 변형시킴을 확인하였다.

평행한 벽 사이에 원형배관(circular pipeline)을 놓고 그 주위의 유동특성에 대한 수치연구를 수행하였다. 비압축성 유체를 가지고, Navier-Stokes 방정식을 풀었고 3차 풍상(upwind) 차분의 수치해법을 이용하였다. 한쪽 벽과의 거리가 매우 작아질 때, 볼텍스 떨어짐이 상당히 억압되는데 이것은 벽 경계와의 상호 박리 작용 때문으로 간수된다. 본 연구는 레이놀드 수의 변함과 물체가 벽에 접근함에 따른 볼텍스 떨어짐의 특성을 규명하는데 있다. 원형배관 후류와 평행벽내 유기된 박리의 상호작용을 집중적으로 다루며 서로 다른 조건에서 박리와 와역한(vorticity dynamics)의 특성을 해석하였다.

The ocean wave is hydrodynamically investigated to get more reliable solution. To improve the computational accuracy more fine grids are used with relatively less computer storage on the free surface. One element of the free surface is discretized into more fine grids because the free-surface waves are much affected by the grid size in the finite difference scheme. Here the multi-grid method is applied to confirm the efficiency for the S103 ship model by solving the Navier-Stokes equation for the turbulent flows. According to the computational result approximately 30% can be improved in the free surface generation, Finally the limiting streamlines show numerical result is similar to the experiment by twin tuft.

Numerical analysis of two-fluid flows for both water and air is carried out. Free-Surface flows with an arbitrary deformation have been simulated around two dimensional submerged hydrofoil. The computation is performed using a finite volume method with unstructured meshes and an interface capturing scheme to determine the shape of the free surface. The method uses control volumes with an arbitrary number of faces and allows cell-wise local mesh refinement. the integration in space is of second order based on midpoint rule integration and linear interpolation. The method is fully implicit and uses quadratic interpolation in time through three time levels The linear equation systems are solved by conjugate gradient type solvers and the non-linearity of equations is accounted for through picard iterations. The solution method is of pressure-correction type and solves sequentially the linearized momentum equations the continuity equation the conservation equation of one species and the equations or two turbulence quantities.

The effect of the submerged high speed vessel on the ocean wave is made clear in the point of hydrodynamics view. In connection to the design of high speed ship, the flow analysis is carried out to predict the pressure distribution for drag and lift. The purpose of the research is to help the preliminary design of the economic hull form advancing under the ocean wave by estimating the resistance performance and the wave behaviour. In the present study, more efficient numerical approaches are investigated for the viscous flow analysis around a submerged NACA0012 hydrofoil with the laminar and incompressible fluid. Through the numerical simulation, it is found that the new numerical method becomes more efficient primarily due to the fact that the wave elevation is reasonably developed.

In connection to the design of high speed vessels, the numerical simulation is carried out to make clear the property of flows and breaking phenomena around the catamaran. It is because the bradking phenome-non is closely related to the free-surface turbulent flow. The free-surface wave and transverse velocity vectors are calculated around the twin and demi hull of the catamaran. Computed results are applied to detect the appearance of sub-breaking waves around the hull. The critical condition for their appearance is studied at two Froude numbers of 0.45 and 0.95. The nu-merical analysis shows that the breaking is more serious near the twin hull rather the demi hull. To simu-late the flows, the Navier-Stokes solver is invoked with a free-surface. The computation is made only in half a domain because it is symmetric in the shape.