• Advances in aircraft and spacecraft science
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• 제4권1호
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• pp.37-52
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• 2017

Gas turbines operating in dusty or sandy environment polluted with micron-sized solid particles are highly prone to blade surface erosion damage in compressor stages and molten sand attack in the hot-sections of turbine stages. Commercial/Military fixed-wing aircraft engines and helicopter engines often have to operate over sandy terrains in the middle eastern countries or in volcanic zones; on the other hand gas turbines in marine applications are subjected to salt spray, while the coal-burning industrial power generation turbines are subjected to fly-ash. The presence of solid particles in the working fluid medium has an adverse effect on the durability of these engines as well as performance. Typical turbine blade damages include blade coating wear, sand glazing, Calcia-Magnesia-Alumina-Silicate (CMAS) attack, oxidation, plugged cooling holes, all of which can cause rapid performance deterioration including loss of aircraft. The focus of this research work is to simulate particle-surface kinetic interaction on typical turbomachinery material targets using non-linear dynamic impact analysis. The objective of this research is to understand the interfacial kinetic behaviors that can provide insights into the physics of particle interactions and to enable leap ahead technologies in material choices and to develop sand-phobic thermal barrier coatings for turbine blades. This paper outlines the research efforts at the U.S Army Research Laboratory to come up with novel turbine blade multifunctional protective coatings that are sand-phobic, sand impact wear resistant, as well as have very low thermal conductivity for improved performance of future gas turbine engines. The research scope includes development of protective coatings for both nickel-based super alloys and ceramic matrix composites.

• 복식
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• 제65권6호
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• pp.79-98
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• 2015

This article studied women's headdresses that appeared in the paintings of Joseon Dynasty. This examined the shapes of women's headdresses painted in genre paintings, record paintings and nectar ritual paintings from Joseon Dynasty and compared them to literatures and relics in order to analyze their types and characteristics. Headdress can be categorized into three types: (1) square cloth worn on the top of the head; (2) a kind of small cap; (3) Cloth that completely covers the head. The first type of headdress resembles the shape of Garima. In the early period of Joseon Dynasty, it was worn not only by Gisaeng, but also by both upper and lower class women. The second type of headdress includes a cap made by connecting several cloths, round cap, and cone-shaped cap. These two types are worn on top of the head. However, sometimes these were worn between the head and the chignon to fix the chignon. Also, these were used as hair accessories for decorative purposes. In particular, old women wore these headdresses and braided their white hair around them to fix the chignon. This way, the headdress not only kept the head warm, but also hid the old women's scanty hair. Headdress was usually made of black fabric and it was a simple hair accessory that replaced the wig. The third type of headdress was widely worn among lower class women. The cloth completely covered the head so that the hair would not fall when working. It also provided protection from cold and hot weather. According to paintings, there were many ways of wearing the cloth around the head.

• Journal of Preventive Medicine and Public Health
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• 제2권1호
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• pp.81-87
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• 1969

Three Combinations of cloths were evaluated for the protective effects of different kinds of clothings in cold environments. Table 1 shows the components of the three models of clothings. A prototype was made by putting a sheet of vinyl at the middle layer of raw cotton in a fabric-quilt cloths. A glove mannequin was covered by each of these cloths. The globes contained 1,000 cc of hot water about $40^{\circ}C$. Tele-thermistors were fixed in order to check the temperature of cloths space and water temperature for evaluation of calorie-loss and climate of clothings. Results are summarized as follows: 1) Without wind, there is no significant difference of air temperatures between sti-parka and quilt-wear clothing. 2) The prototype with vinyl sheet best protects against wind, the next is the ski-parka. Quilt-wear protects the least. 3) It is well-known that a working-clothing needs not have any separate liners nor outers. 4) For innermost layer of a clothing preventing cold, a cotton-fabrics is recommended and a water-proof cloths for outer layer. 5) Heat-loss was calculated from the cooling degrees of water. Calorie-loss was $910cal/m^2/hr$. when bared, but with the prototype of vinyl sheets the calorie-loss was $350cal/m^2/hr$. (38.5% of bared). Quilt-wear and ski-parka were 380(41.8%) and $440cal/m^2/hr$. (48.4%) respectively.

• 한국재료학회지
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• 제10권5호
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• pp.335-342
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• 2000

리늄판의 미세경도를 압흔 하중 및 온도의 함수로 구하였다. 미세경도의 온도의존성은 상온에서 100$0^{\circ}C$까지의 범위에서 Vickers 압흔기가 내장된 고온 미세압흔기를 이용하여 연구되었다. 미세경도의 하중의존성은 Vickers와 Knoop 압흔기를 이용하여 검토되었다. 압흔 크기 영향은 표준화된 Meyers법칙에 위해 충분히 설명 되었다. 압흔도중 압흔기 아래에서의 가공경화 때문에 어닐링된 리늄판 경도값은 높은 압흔 하중에서 압련되 리늄판의 경도값에 접근하였다. 경도의 하중의존성으로부터 외삽하여 얻어진 하중 영에서의 경도값은 경도값이 다른 열활성을 나타내는 두 개의 다른 기구에 의해 제어됨을 제시하였다. 낮은 온도에서 활성화에너지는 0.02eV 였으며, 한편 높은 온도에서 활성화에너지는 0.15eV 였다. 이때 전이온도는 대략 $250^{\circ}C$ 이었다.

• 지역사회간호학회지
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• 제13권1호
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• pp.17-29
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• 2002

This study was carried out to investigate the effect of Self-foot reflexology (SFR) on the hypertension of workers. The purpose of the research was to evaluate: levels of knowledge, physical and emotional condition, work stress and fatigue on the hypertension of employees in the workplace. Quasi-experimental study was designed in the setting of a nonequivalent control and experimental Group applied by the pre and post test. The total subjects undertaken in the study were total of 34 employees working in three companies in Seoul. The SFR program was consisted of 6 phases. There were 2 minutes for preparation, 4 minutes for slow down, 26 minutes for base reflex, symptoms of a disease reflex and excretion reflex stimulation. Finally, there was 20 minutes relaxation in a comfortable posture and drinking hot water after blood pressure was checked in the order. This program was running 55 minutes a day everyday three times a week during the entire 8 week course. The finding showed blood pressure was reduced significantly. Moreover, the level of total cholesterol. high and low density lipoprotein cholesterol, depression, work stress, and fatigue were decreased in the study. But, they were not statistically significant except as it related to Group comparisons in time. The level of state anxiety was statistically significant between 2 Groups, but not in the time comparison of both Groups. As a summary of the study results, the SFR program was regarded as contributing to the physical and emotional promotion of employees. It had partially increased body circulations of functional organ related to the SFR sites. And, it improved relaxation of physical and mental condition through energy movement 'Chi'. Therefore, the SFR technique should be considered as an effective skill of a nursing program. Furthermore, it can be newly adopted as a nursing curriculum as a part of alternative treatment. However, it still needed to testify its effects through the review study.

• 대한기계학회논문집B
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• 제37권10호
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• pp.919-926
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• 2013

본 연구에서는 소형 저온 유기랭킨사이클 시스템의 작동특성을 파악하기 위하여 R-245fa를 작동유체로 사용한 소형 ORC 발전 시스템을 설계 및 제작하였고, 다양한 저온의 열원온도에 대한 실험적 연구를 수행하였다. 저온 열원을 모사하기 위하여 최고 $150^{\circ}C$의 물을 공급할 수 있는 110 kW급의 전기저항 히터를 제작하였으며, 컨트롤러를 통해서 다양한 열원 온도 및 유량조건에 대한 실험이 가능하도록 구성하였다. 또한, 상용 공기용 스크롤 압축기를 이용하여 팽창기로 개조하고 동력계 및 동기식 모터와 직접 연결하였다. 로드뱅크 및 PI 제어방식을 사용하여 팽창기의 회전속도에 따른 동일 열원온도 조건에 대한 실험을 각각 수행하였으며, 소형 ORC 시스템의 성능에 영향을 미치는 다양한 인자들에 대하여 분석하고 논의하였다.

• 한국의류학회지
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• 제40권5호
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• pp.910-920
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• 2016

This study is to understand the problems of current police raincoats for professional policemen and conscripted policemen. Interviews and a survey were completed to investigate the wearing conditions of current police raincoats. The questionnaire was composed of questions on current wearing conditions of raincoat, motional adaptability, dimensional compatibility, design suitability and demographic information on the research target. The results indicated that the wearing frequency of raincoats had significant difference according to duty and age range. The main reason for the low wearing frequency was the uncomfortableness of working while wearing the raincoat, followed by the inconvenience of managing the raincoat after use and feeling hot while wearing the raincoat. The three most important factors when wearing a raincoat was pleasantness, activity capability and the functionality of the fabric. The satisfaction on body parts during motions tended to be evaluated lower as the raincoat size increased. The results of the dissatisfaction factors indicated that the raincoat hood had the most problems. There was inconvenience when using the equipment belt because officers have to wear their belts inside the raincoat. In regards to the fabric satisfaction level, respondents were less satisfied with ventilation, hygroscopicity, and drying time. Therefor it appeared that the current raincoat had problems due a lack of functionality in regards to ventilation, hygroscopicity, and quick drying; in addition, the satisfaction on motional adaptability had a significant difference according to raincoat size.

• 한국산업융합학회 논문집
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• 제19권1호
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• pp.1-9
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• 2016

In this paper, we propose a new learning control scheme for various walk motion control of biped robot with same learning-base by neural network. We show that learning control algorithm based on the neural network is significantly more attractive intelligent controller design than previous traditional forms of control systems. A multi layer back propagation neural network identification is simulated to obtain a dynamic model of biped robot. Once the neural network has learned, the other neural network control is designed for various trajectory tracking control with same learning-base. The biped robots have been received increased attention due to several properties such as its human like mobility and the high-order dynamic equation. These properties enable the biped robots to perform the dangerous works instead of human beings. Thus, the stable walking control of the biped robots is a fundamentally hot issue and has been studied by many researchers. However, legged locomotion, it is difficult to control the biped robots. Besides, unlike the robot manipulator, the biped robot has an uncontrollable degree of freedom playing a dominant role for the stability of their locomotion in the biped robot dynamics. From the simulation and experiments the reliability of iterative learning control was illustrated.

• 인지과학
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• 제23권1호
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• pp.25-46
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• 2012

우리는 단조로운 과제를 할 때 종종 그만두고 싶은 충동을 느낀다. 이러한 중단 충동은 그 일을 얼마나 오래동안 해 왔는지(시간적 요인) 또는 수행하는 과제의 특정요소(사건 기반 요인)에 따라 달라진다. 이 연구에서는 스트룹 과제와 작업기억과제를 사용하여 시간적 요인(반복)과 사건 기반 요인(인지적 충돌)의 함수로서의 중단 충동의 변화를 살펴보았다. 최소작업의 법칙을 비롯한 최신 이론과 마찬가지로 기억 과제에서 중단 충동은 어려운 시행 다음에 더욱 큰 것으로 나타난 반면, 스트룹 과제에서는 반응이 비효율적인 시기인 수행의 초기(초심자) 단계에서만 일치 시행보다 불일치 시행 다음에 중단 충동이 더 큰 것으로 나타났다. 이는 인지적 갈등에 대한 회피반응임을 입증하는 결과이다. 시간적 측면에서 보면 중단 충동은 초기 단계보다 후기 단계에서 더 컸다. 이러한 연구 결과는 만족 지연에 관여하는 비교적 강렬한 동기적 노력의 본질을 명확하게 설명하고 있다.

• 한국콘텐츠학회논문지
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• 제7권10호
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• pp.157-164
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• 2007

인류가 살아남기 위해서 수렵과 채취를 하는 동안 저장을 위해 자연스럽게 만들어진 그룻은 위대한 발명 이었다. 집을 지을 때도 자연의 일부로서 자연과 닮은 집을 지었고, 사계절을 지내기 위해 음식을 저장하는 방법을 연구하여 집안 곳곳에 저장창고와 저장용기를 배치하여 계절에 관계없이 음식을 먹을 수 있도록 했다. 그러나 현대에 와서 사회의 변화와 과학의 발달로 자연의 순수한 재료로 만들어지던 그룻과 저장용 기들이 플라스틱과 철이라는 새로운 재료들로 만들어져 생활의 편리함을 안겨주었으나 그에 따른 부작용도 생겨나고 있고 집집마다 냉장고에 김치를 보관하나 예전의 그 맛이 아니다. 요즈음 웰빙 열풍과 함께 한국의 음식이 세계화 되고 있고, 김치의 세계화로 김치를 저장했던 옹기에 대한 관심도 증가하고 있다. 본 연구는 예부터 발전해온 도기의 일종인 옹기의 발전사를 문헌을 통해 알아보고 과학적인 실험을 통해 선조들의 지혜가 담긴 옹기의 특성을 연구함으로서 옹기의 장점과 필요성을 알리고 더 나아가 옹기의 특성을 활용한 친환경적인 기물의 개발에 힘쓰도록 유도함에 그 목적이 있다.