• 전자공학회논문지SC
• /
• 제47권2호
• /
• pp.55-59
• /
• 2010

현재 움직이는 물체의 운동을 제어하기 위해 하중이라는 개념의 사용이 시도되고 있다. 하중이라는 제어 개념으로 불확실성으로 인한 비선형성을 포함한 시스템에서 보다 신뢰성 있는 제어값을 찾기 위해, 기존의 선형화 방법에 의한 상태방정식에서 제어값을 찾는 문제와 달리 비선형 하중 모델에서 직접 제어 값을 찾는 방법이다. 본 논문에서는 동력이 없고 제어되지 않는 자유 낙하 물체를 비선형 하중모델로 구현해보고, 외란에 따라 낙하하는 물체에 작용하는 하중값을 분석해 본다. 또한 이러한 외란에 의해 발생한 하중값에 따른 낙하 경로를 구한다. 본 논문의 연구결과는 비선형 모델 예측 제어 시스템에 적용하여 다 연장로켓, 추진력을 갖지 않은 GPS 유도탄 그리고 우주비행체의 지상귀환 제어시스템의 정밀도 향상을 위해 이용될 수 있다.

• 한국콘텐츠학회논문지
• /
• 제15권12호
• /
• pp.387-406
• /
• 2015

최근 감정노동은 감정노동전략의 핵심인 표면조절행위 및 심층조절행위와 관련하여 병원근로자들에게 있어 필수불가결한 상황이 되고 있다. 본 연구는 이러한 병원근로자들의 감성지능과 감정노동전략 간의 관계를 실증적으로 밝히기 위한 연구이다. 연구의 목적에 따라 본 연구에서는 병원근로자들을 대상으로 설문을 시행하고 이를 실증적으로 분석하였다. 데이터 분석으로는 PLS 구조방정식 분석법을 사용하였다. 연구결과, 병원근로자들의 감성지능 즉, 자기감정이해, 타인감정이해, 감정조절 및 감정활용은 병원근로자들의 심층조절행위에 유의한 긍정적인 영향을 미쳤고, 또한 병원근로자들의 심층조절행위는 조직애착, 지식공유의도 및 혁신활동에 유의한 긍정적 영향을 미치는 것으로 밝혀졌다.

• Journal of Biosystems Engineering
• /
• 제18권4호
• /
• pp.344-350
• /
• 1993

The purpose of this study is to develop design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage. The main results of this study are as follows. 1. A wheel-lug ought to receive a special resistance in downward direction which resists the lug's upward motion on wet sticky soil surface. The authors introduce a new academic name of the "lift resistance(上昇抵抗力, 상승저항력)" for such a force which resists retraction of a wheel lug from the soil in the upward trochoidal motion. This force is composed of the frictional force acting on the trailing and the leading lug side, and the "perpendicular adhesion(鉛直付着力, 연직부착력)" acting on the lug face and the undertread face on adhesive soil. 2. The "lift resistance ratio(上昇抵抗力係數, 상승저항력계수)" and the "perpendicular adhesion ratio(鉛直付着力係數, 연직부착력계수)" were defined, which are something similar to the definition of the motion resistance ratio, the traction coefficient, etc. 3. The design equation of the optimum weight of a rotary tiller mounted on the tractor derived by calaulating the forces acting on the rotary blades. 4. The design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage were derived. It becomes clear that the optimum weight of a rotary tiller and a tractor can be estimated in planning design by means of putting about 21 design factors of the target into the equation. These equations are useful for planning design to estimate the optimum dimensions and specifications of a rotary tiller as well as a tractor by the use of known and/or unknown design parameters.

• 임상간호연구
• /
• 제22권3호
• /
• pp.314-326
• /
• 2016

Purpose: The purpose of this study was to understand the experience of emotional labor of clinical nurses in medical institutes. Methods: A total of 26 nurses from 11 hospitals participated in the study. Six focus groups were organized and 4 to 5 nurses took part in each group. The compositional factors of groups included clinical experience, age, gender, work place and position. Data collection was conducted through focus group interview and it was proceeded by the time of data saturation. In this qualitative study, content analysis was conducted. Results: Five themes, 14 categories, and 33 subcategories, were emerged. The themes were 'Restrain themselves', 'Communion to the patients', 'Working environment provoking emotional tension', 'Respond to emotional events', 'Recovery of emotional energy'. Conclusion: Results indicated that surface acting of emotional labor such as, repression of personal desire and presenting the emotions that the organization ask nurse to express was related to psychosomatic symptoms, depression, burnout, poor job performance, increased mistakes, and low job satisfaction which eventually leads to nurses' turnover. In order to reduce negative influence of emotional labor, it is necessary to build positive organizational culture, to provide support from managers and co-workers. It is also important to improve work environment in order to do more deep acting since sharing emotions with patients can reduce the negative influence of emotional labor.

• Wind and Structures
• /
• 제26권1호
• /
• pp.35-43
• /
• 2018

This paper describes the effect of different testing parameters (configuration of infrastructure and truck position on road) on truck aerodynamic coefficients under cross wind conditions, by means of a numerical approach known as Large Eddy Simulation (LES). In order to estimate the air flow behaviour around both the infrastructure and the truck, the filtered continuity and momentum equations along with the Smagorinsky-Lilly model were solved. A solution for these non-linear equations was approached through the finite volume method (FVM) and using temporal and spatial discretization schemes. As for the results, the aerodynamic coefficients acting on the truck model exhibited nearly constant values regardless of the Reynolds number. The flat ground is the infrastructure where the rollover coefficient acting on the truck model showed lowest values under cross wind conditions (yaw angle of $90^{\circ}$), while the worst infrastructure studied for vehicle stability was an embankment with downward-slope on the leeward side. The position of the truck on the road and the value of embankment slope angle that minimizes the rollover coefficient were determined by successfully applying the Response Surface Methodology.

• Wind and Structures
• /
• 제30권1호
• /
• pp.15-27
• /
• 2020

This paper reports the study on development and verification of numerical models and analyzes of flow at high speed around structural elements in the shape of a curved pipe (e.g., a fragment of a water slide). Possibility of engineering estimation of wind forces acting on an object in the shape of a helix is presented, using relationships concerning toroidal and cylindrical elements. Determination of useful engineering parameters (such as aerodynamic forces, pressure distribution, and air velocity field) is presented, impossible to obtain from the existing standard EN 1991-1-4 (the so-called wind standard). For this purpose, flow at high speed around a torus and helix, arranged both near planar surface and high above it, was analyzed. Analyzes begin with the flow around a cylinder. This is the simplest object with a circular cross-section and at the same time the most studied in the literature. Based on this model, more complex models are analyzed: first in the shape of half of a torus, next in the shape of a helix.

• 한국해양공학회지
• /
• 제16권6호
• /
• pp.7-17
• /
• 2002

Recently, artificial rocks, instead of buoys, have been placed on the submerged breakwater to indicate its location. The accurate estimation of wave forces on these rocks is deemed necessary for their stability design. Characteristics of the wave force, however, are expected . to be very complicated because of the occurrence of breaking or post-breaking waves. In this regard, wave forces exerted on an artificial rock have been investigated in this paper. The maximum wave force has been found to strongly dependent on the location and shape of the artificial rock that is placed on the submerged breakwater. The plunging breaker occurs near the loading cram edge of a submerged breakwater, which cause impulsive breaking wave force on the rock. Using the Morison equation, with the velocity and acceleration at the front face of the artificial rock and varying water surface level, it is possible to estimate wave forces, even impulsive breaking wave forces, that are acting on the rock installed on a submerged breakwater. The vertical wave force is also found to depend, significantly, on the buoyant force.

• 한국군사과학기술학회지
• /
• 제20권3호
• /
• pp.405-412
• /
• 2017

In the present study, two phase flows around a projectile vertically launched from an underwater platform have been numerically investigated by using a three dimensional multi-phase RANS flow solver based on pseudo-compressibility and a homogeneous mixture model on unstructured meshes. The relative motion between the platform and projectile was described by six degrees of freedom(6DOF) equations of motion with Euler angles and a chimera technique. The propulsive power of the projectile was modeled as the fluid force acting on the lower surface of the body by the compressed air emitted from the platform. Qualitative analysis was conducted for the time history of vapor volume fraction distributions. Uncorking pressure around the projectile and platform was analyzed to predict impact force acting on the surfaces. The results of 6DOF analysis presented similar tendency with the surficial pressure distributions.

• 한국직업건강간호학회지
• /
• 제24권4호
• /
• pp.331-339
• /
• 2015

Purpose: The purpose of this study was to investigate the moderating effects of social support between emotional labor and job satisfaction in clinical nurses. Methods: Participants were 311 clinical nurses and data were collected from July 11th to 18th, 2014. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson correlation coefficient and hierarchical multiple regression with SPSS 21.0. Results: The job satisfaction indicated a significant relationship to surface-acting (r=-.191, p=.001), deep-acting (r=.179, p=.002) and social support (r=.342, p<.001) respectively. Emotional labor significantly affected job satisfaction (F=11.592, p<.001), and explained 5.4% of the variance in job satisfaction. The social support acted as a moderator on the relationship between emotional labor and job satisfaction at significant level (F=11.416, p<.001). Conclusion: The results of this study suggest that it is important to develop social support promoting and stress relief program for clinical nurses to improve job satisfaction.

• 대한조선학회지
• /
• 제27권1호
• /
• pp.63-72
• /
• 1990

2차원 부유체가 자유 표면상의 평균 위치로 부터 작은 진폭의 비정상 운동을 할 때, 물체에 작용하는 선형 동유체력을 과도 Green 함수를 사용한 적분 방정식법에 의하여 시간 영역에서 수치해석 하였다. 특히 시간 영역에 따라 과도 Green 함수를 급수전개 또는 접근전개시킨 후 사용함으로써, 시간 영역에서 직접해석시에 단점으로 지적되고 있는 수치 계산 소요시간을 단축시켰다. 계산 예로는 원형 단면 주상체의 강제 상하동요 및 수평 동요시의 동유체력을 수치 해석 하였으며, Fourier 변환 후 진동수 영역에서의 해당 값과 비교 도시하였다.