• Journal of Periodontal and Implant Science
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• 제34권1호
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• pp.71-81
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• 2004

Peri-implantitis could be the result of biomechanical and occlusal overload as well as microbiologic invasion. The dental implant may be more susceptible to dental plaque than the natural tooth, as the predictability of a stable soft tissue attachment complex has not yet been confirmed. With the development of peri-implantitis, the implant surface would be exposed to the oral environment and becomes coated with bacteria. The objective of therapy for this condition is to regain integration of the implant with bone. Since fibroblast adherence to surfaces is impeded by endotoxin, it would seem that decontamination would be desirable to obtain maximum osseointegration. The purpose of this study was to determine whether various chemotherapeutic and mechanical treatments(distilled water, air-powder abrasive, hypersaturated citric acid, tetracycline) can detoxify contaminated titanium implant surface by means of kinetic LAL test. Experimental rough surface titanium disks were fabricated. All of them were divided into two groups(A.a group and P.g group) and each contaminated by A. actinomycetemcomitans and P. gingivalis suspension. Contaminated disks were treated with distilled water, air-powder abrasive, citric acid and tetracycline, and then all disks were placed into LPS-free water for elution. The results were as follows : 1. In A.a group, LPS elute level of all test groups were significantly lower than control group(p<0.05). 2. In A.a group, LPS elute level of test 2, test 3 and test4 groups were significantly lower than that of control group(p<0.05). But, among the test 2, test 3, test4 groups, the significant differences were not detected. 3. In P.g group, LPS elute level of test 2, test 3 and test 4 groups were lower than that of control group(p<0.05). But, among the test groups, the significant differences were not detected. From the result of this study, it would be concluded that air-powder abrasive, hypersaturated citric acid and tetracycline treatments may be effective at reducing endotoxin level on rough titanium implant surfaces, and can be clinically used. But the treatments in peri-implantitis differentially impact osseointegration making one method clinically superior. To gain this knowledges, further molecular biologic and histopathologic studies should be developed.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.261-268
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• 2018

전력수요와 부하용량이 증가 되어감에 따라 부하에 전력공급을 위한 간선으로서의 케이블은 설치 시간의 과다와 공간의 제약으로 사용이 제한적이다. 이런 문제를 해결하기 위한 간선 시스템으로 대전류를 효율적으로 공급해 줄 수 있는 버스웨이 시스템의 사용이 증가되고 있으나, 신뢰성의 검증을 위한 시험평가 방법과 그에 대한 결과 제시가 부족한 실정이다. 본 논문에서는 에폭시를 주절연으로 하는 버스웨이 시스템의 신뢰성 검증을 위해서 IEC 61439-6에서 제시된 시험항목이외에 장기 사용성과 신뢰성을 평가할 수 있는 시험항목을 선정하였다. 열 및 전기적 스트레스를 동시에 인가하여 최대한 실사용 상태를 반영한 복합가속열화시험을 실시하였으며, 50년 수명 조건을 충족하도록 열화 조건을 선정하여 버스웨이 시스템의 절연성능 확인시험을 통해 수명을 만족함을 확인하였다. 또한, 버스웨이가 설치되는 온도, 습도 및 부하전류 사용 환경에 대한 적합성 확인에 대한 신뢰성 평가 시험항목으로서 열적 과전류 시험, 침수시험, 냉충격시험, 온도 사이클 시험을 선정하여 실시하였으며, 확인 시험을 통해 시험 전후의 특성 변화와 이상 유무를 검토하였다. 이 결과들로부터 에폭시 절연형 버스웨이 시스템의 평가항목으로서 본 논문에서 제시한 시험항목이 적절하고, 그에 대한 제품의 성능도 우수함을 확인하였다.

• 지능정보연구
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• 제10권1호
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• pp.93-107
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• 2004

급속한 인터넷의 확산으로 이제 웹은 단지 커뮤니케이션이나 홍보, 쇼핑의 수단뿐이 아닌 정보의 보급 및 창고로서의 역할이 더욱 커지고 있다. 또한, 과거의 웹 기반 기술인 하이퍼텍스트에 멀티미디어 기술이 접목되면서 하이퍼미디어 개념이 도입되어 텍스트 외의 이미지, 동영상, 사운드 등 다양한 형식의 미디어를 통해 정보를 접할 수 있게 되었다. 그러나, 이러한 정보공간에서 정보의 양이 기하급수적으로 증가함에 따라 웹 이용자들은 인지과부하(Cognitive overload)로 인하여 웹 상에서 방향감 상실, 정보공간에서 길 잃음 둥의 다양한 어려움을 겪고 있다. 이러한 문제를 해결하기 위해 많은 연구자들이 지속적으로 연구하고 있으며 그 중의 하나가 공간 개념(Spatial concept)을 적용한 공간 메타포(Spatial metaphor) 연구이다. 본 연구에서는 이러한 공간 메타포 개념을 이용하여 새로운 개념의 네비게이션 방식의 웹사이트를 개발하고 이를 Atomic-Map이라고 하였다. Davis 교수가 제안한 기술수용모형 (TAM) 모형을 이용하여 Atomic-Map의 사용성을 분석한 결과 Atomic-Map을 이용하여 정보공간에서 복잡한 네비게이션 하에서 발생할 수 있는 여러 가지 문제를 해결할 수 있음을 실증적으로 검증하였다.

• 가정과삶의질연구
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• 제4권2호
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• pp.103-117
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• 1986

The purpose of this study is to provide the basic information for the improvement of housewives consciousness and satisfaction of household work by analyzing the data regarding the housewives consciousness and satisfaction toward household work. The research problems was described as follows; 1) How independent variables influence the housewives consciousness of household work. 2) How independent variables influence the satisfaction of household work. 3) How relate the housewives consciousness and the satisfaction of household work. The research was conducted on 354 housewives in Seoul during the end of January and the beginning of March, 1986. As for the measurement of the instrument, questionnaire with 46 items was made by investigator. The data were analyzed by frequency, percentage, mean and t-test, F-test, Scheffe-test, Pearson-r. The results were summarized as follows; 1) Among the independent variables, the ages of housewives, durations of marriage, psychologica satisfaction were variables to have influence on the housewives consciousness towark household work. 2) Among the independent variable,s the socio-economic status, durations of marriage, psychological satisfaction were variables to have influence on the satisfaction of household work. 3) There were strong positive correlationship between the housewives consciousness and the satisfaction of household work. As a result, it is necessary to minimize the repetition and the overload of house-hold chores through the rationalization of household work and also to divide householdwork properly to family members. We let the housewives feel that her ability can be obtained from the household work. Especially the housewives must have a clear and a high level of consciousness of the household work an expect to receive high value of her household work from the family members. In order to do so, it seems to be important that housewives makes on great effort to have a positive value system and attitudes toward the consciousness and satisfaction of household work. We also must develop those factors through school and home education.

• 대한간호학회지
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• 제34권6호
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• pp.1097-1107
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• 2004

Purpose: The purpose of this study was to develop a job stress scale for hospital-based home care nurses in Korea. The process was construction of the conceptual framework, development of the preliminary items, verification of the content validity, item analysis and test of the reliability. The preliminary items were based on literature review and in-depth interviews with home care nurses. As a result, eight categories and sixty items were selected. These were reviewed by seven specialists for content validity and finally fifty one items were chosen. Data was collected from 180 home care nurses who were engaged in 87 hospitals from August to September 2003. The result of item analysis one was excepted, The final item count was 50. Categories were as follows: overload work(8 items), lack of specialized knowledge and technique(5 items), ethical dilemma(4 items), role conflict(5 items), interpersonal relationships(6 items), visiting home environment(9 items), driving conditions(4 items) and lack of administrative support(9 items), The reliability of the scale by Cronbach's alpha was .948 and the domain's reliability ranged from .649 to .841. The result of this study could be used to measure the job stress of home care nurses. However, for further validity and reliability, repeated studies will be necessary.

• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.301-308
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• 2015

In this paper, we propose an LTBC (Low Tension and Load Balance Control) scheme to improve a coiling shape control by reduction the tension fluctuation by the torque disturbance in the down coiler process of hot strip mills. The proposed controller is a combination of an LTC to control the overload at load-on in the mandrel and an LBC to regulate the load balance of the upper and bottom pinch roll. A tension calculation model is suggested with the concept of the tension deviation. The effectiveness of the proposed control scheme is verified from simulation under a disturbance of the pinch roll torque. Using a field test, we show that the performance of the shape and tension control is improved by the LTBC control.

• 대한간호학회지
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• 제25권1호
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• pp.110-123
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• 1995

This study was done to analyze the relationship between task stress and morale in psychiatric nursing assistants. The subjects were 118 psychiatric nursing assistants selected from the National Mental Hospital in Seoul and 18 non-medical mental institutions. The data were collected from October 22 to November 12, 1994. The instruments used for this study were modified PNOSS (Psychiatric Nurse Occupational Stress Scale) which was developed by Bai and modified the Morale scale which was developed by Oh. The confidence varification of these instruments were computed and Cronbach $\alpha$=.9255, .9260. Data were analyzed by t -test, ANOVA on 5% significant level and Pearson correlation coefficient. The results of the study are as follows : 1. The average work stress scores of subjects were 2.83. Among the work stress factors : the conflict with nurse was identified as the most stress factor. There was significant relationship between the degree of work stress and the variables of psychiatric Nursing Assistants such as the marital status, educational level, religion, job satisfaction, working place, predicted period of work. 2. Average total morale scores for the subjects was 3.08. There was a significant relationship between the degree of morale and variables of psychiatric nursing assistants such as working place, certification as a nursing assistant, job satisfaction, opportunity for practical education and predicted period of work. 3. There was a significant relationship between the degree of morale and work stress factors such as administration problem, work overload.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.169-171
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• 2008

초전도케이블의 기술적 경제적 타당성에 대한 논의가 계속 진행되고 있는 가운데 이를 검증하기 위한 실계통 시험이 미국, 중국 및 일본을 포함한 주요 선진국들에서 이루어지고 있다. (1) 대용량 송전 및 절연성능 측면에서 장점을 가지고 있는 초전도케이블이 실제계통에서 적용한 예가 지금까지 많지 않은 이유는 막대한 초기투자 비용과 함께 신기술 도입에 따른 기술적 신뢰성 확보를 꼽을 수 있다. 특히 케이블 자체의 전기적 특성과 함께 냉각시스템의 신뢰성은 초전도케이블 기술의 상용화를 위해서 반드시 확보되어야 하며 냉각시스템의 고효율와 함께 장기운전에 따른 냉각시스템의 안정성 및 기기적 특징들이 우선적으로 파악되어야 할 것이다. 본 논문에서는 냉각시스템의 신뢰성을 검증하기 위한 실험의 일환으로 전류와 냉각시스템에 내장되어 있는 히터를 이용하여 열부하를 동시에 인가, 냉각시스템의 냉각용량 과부하 상태를 모의하여 냉각시스템의 반응성을 평가하였다.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2276-2283
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• 2018

A 50kW-4000rpm interior permanent magnet synchronous machine (IPMSM) applied to the high-performance electric vehicle (EV) is introduced in this paper. The main work of this paper is that a 2-D T-type lumped-parameter thermal network (LPTN) model is presented for IPMSM temperature rise calculation. Thermal conductance matrix equation is generated based on calculated thermal resistance and loss. Thus the temperature of each node is obtained by solving thermal conductance matrix. Then a 3-D liquid-solid coupling model is built to compare with the 2-D T-type LPTN model. Finally, an experimental platform is established to verify the above-mentioned methods, which obtains the measured efficiency map and current wave at rated load case and overload case. Thermocouple PTC100 is used to measure the temperature of the stator winding and iron core, and the FLUKE infrared-thermal-imager is applied to measure the surface temperature of IPMSM and controller. Test results show that the 2-D T-type LPTN model have a high accuracy to predict each part temperature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권7호
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• pp.1721-1736
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• 2013

Black and gray hole attack is one kind of routing disturbing attacks and can bring great damage to the network. As a result, an efficient algorithm to detect black and gray attack is important. This paper demonstrate an adaptive approach to detecting black and gray hole attacks in ad hoc network based on a cross layer design. In network layer, we proposed a path-based method to overhear the next hop's action. This scheme does not send out extra control packets and saves the system resources of the detecting node. In MAC layer, a collision rate reporting system is established to estimate dynamic detecting threshold so as to lower the false positive rate under high network overload. We choose DSR protocol to test our algorithm and ns-2 as our simulation tool. Our experiment result verifies our theory: the average detection rate is above 90% and the false positive rate is below 10%. Moreover, the adaptive threshold strategy contributes to decrease the false positive rate.