• 한국태양에너지학회 논문집
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• 제31권4호
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• pp.80-86
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• 2011

Investigation of the effective soil thermal conductivity(k) is the first step in designing the ground loop heat exchanger(borehole) of a geothermal heat pump system. Another important factor is the borehole thermal resistance($R_b$). Thermal response tests offer a good method to determine the ground thermal properties for the total heat transport in the ground. This is done by supplying a constant heat power into a borehole heat exchanger. There are two methods to supply a constant heat power. One is to employ the electricity provided by Korea Electric Power Corporation(KEPCO). The other is to use electricity generated by a generator. In this study, the power supply regulation was found to reduce when the electricity generated by the generator was used. This is because the generator evaluated with the power supply characteristically reduces the power supply regulation between an overload and a complex using. But it sometimes occurs a power supply regulation in In-situ thermal response test. In this case getting of k,$R_b$ requires delay times and restored normal state. However, the effect of the delay times and restored normal state on the soil thermal conductivity and borehole thermal resistance is very small. Therefore it is possible to use a generally accepted delay times and restored normal state in the analysis. In this work, it is also shown that an acceptable range of ${\Delta}k$, ${\Delta}R_b$ for normal state and regulation state might be approximately 0.01-0.16W/m k, and -0.004-0.007m K/W, respectively. Thus, restored normal state of power supply regulation is valuable to recommend.

• 한국산업융합학회 논문집
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• 제24권6_2호
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• pp.801-808
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• 2021

In this paper, a numerical analysis was conducted on the effect of the flow control valve of a oscillation water column(OWC) type wave power generator turbine. The OWC wave power turbine operates with compressed air in the air chamber according to the change of wave height. When the wave height changes rapidly, a flow control valve is required due to overload of the turbine and reduced efficiency. Therefore, in this paper, a flow control valve with an opening angle of 60 degrees was installed in the front of the turbine, and the pressure drop, torque, and overall performance were calculated according to the change of turbine RPM and flow rate of turbine inlet. In conclusion, the flow control valve with an opening angle of 60 degrees affects when the turbine rotates at low rotation and the inlet flow rate is large. But it does not have a significant effect on overall turbine performance and it is necessary to find the optimal angle in the future works.

• Physical Therapy Rehabilitation Science
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• 제7권4호
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• pp.191-196
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• 2018

Objective: The purpose of this study was to investigate the effects of 5 different personalities on job stress in physical therapists. Design: Descriptive cross-sectional study. Methods: Structured self-report questionnaires consisted of demographic items, 5 types of personalities, and occupational stress. A questionnaire was distributed to 420 physical therapists working in Seoul and Incheon who had voluntarily agreed to participate in the study after the purpose of the study was explained. Of the 420 questionnaires, 405 questionnaires were collected and showed a recovery rate of 96.4%, of which 28 cases were excluded, leaving a total of 377 questionnaires being used for analyses. Pearson correlation analysis was performed to investigate the correlation of job stress and five personalities types. In addition, multiple regression analysis was performed to investigate the effect of general and occupational characteristics of physical therapist on job stress and the effect of personality type on occupational stress. All statistical significance levels were set at p<0.05. Results: The highest number of subjects, which were the physical therapists, showed the tendency to have a sincere personality, followed by affinity, openness, extroversion, and neuroticism. Physical therapists reported to be the most stressed in the order of professional role conflict, overload of work, work relation with a physician and supervisor, interpersonal relationship with patient and caregiver. The higher the level of affinity and sincerity, the lower the amount of stress received by the therapist from the interpersonal relationships between the patient and caregivers. On the other hand, the greater the level of openness and sincerity, the lower the stress levels related to professional role conflict. Conclusions: This study showed that the personality type and job stress of physiotherapists had a statistically significant effect. It is very important for physiotherapists to find their own way of coping with stress, which is satisfactory and appropriate for their job, because it is related not only to individual problems but also to the quality of patient care and medical services. Therefore, it is necessary to continue conducting research on how to relieve the stress levels of physical therapists according to their personality characteristics.

• Journal of Periodontal and Implant Science
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• 제37권1호
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• pp.137-150
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• 2007

CADIA(Computer-assisted densitometric image analysis) method is used to analyze bone density changes around the implants. The usefullness and reproducibility of the method was assessed. We tried to find out if there is any possibility to quantitiate and qualitify peri-implant bone density change as time passes. And we concluded that this newly developed linear analysis is efficient for analyzing peri-implant bone density change non-Invasively. In this study, 2152 machined $Br{\aa}nemark$ fixtures installed from 1994 to 2002 in the department of Periodontics, Dental hospital of College of Dentistry, Yonsei University were included. Of these fixtures 22 radiographically analyzable failed fixtures were used as experimental group, and 22 successful implants placed in the same patient were used as control group. 1. 57 out of 1635 machined $Br{\aa}nemark$ standard and Mk II implants system failed, the survival rate was 96.5%. And 11 out of 517 machined $Br{\aa}nemark$ Mk III and Mk IV implants system failed, the survival rate was 97.9%. Total survival rate was 96.8%. 2. 22 failed implants were used for the analysis, 10 of which failed before prosthetic treatment due to infection and overheating. 12 failed due to overload after prosthetic treatment, 63.6% of which failed during the early phase of functional loading, i, e. before 1 year of loading. 3. Bone density change values around coronal region of the failed implants were $-6.54{\pm}6.35$, middle region were $-3.53{\pm}5.78$, apical region were $-0.75{\pm}10.33$, resulting in average of $-3.71{\pm}8.03$. 4. Bone density change values around coronal region of the successful implants were $4.25{\pm}4.66$, middle region were $6.33{\pm}5.02$, apical region were $9.89{\pm}4.67$, resulting in average of $6.27{\pm}5.29$. 5. There was a statistically significant difference between two groups (p<0.01). In conclusion, the linear analysis method using computer-assisted densitometric image analysis could be a useful method for the analysis of implants, and could be used for future implant researchs.

• 한국지역지리학회지
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• 제19권3호
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• pp.454-475
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• 2013

대구는 2011년에 세계육상선수권대회(IAAF World Championships)를 개최하였다. 조직 위원회는 이 대회를 통해서 대구에 대한 세계적인 인지도를 강화하고, 세계적인 스케일에서 관광과 투자를 촉진함으로써 최근 대구의 경기침체를 극복하고자 하였다. 한국에 거주하는 외국인의 관점에서 쓰여진 본 논문은 문화지리 분석 방법을 혼합하여 세계육상선수권대회로 인해 파급된 관광과 투자의 영향을 평가하였다. 본 논문은 대규모 이벤트를 활용한 장소의 생산을 고찰하기 위해 세 단계의 '영토화(territorialisation)' 접근법를 적용하였으며, 특히 세계육상선수권대회가 개최되기 전과 개최되는 동안의 재현 활동(representational efforts)을 살펴보았다. 이 과정에서 웹사이트, 안내책자 등과 같은 대회 관련 홍보물이 주로 사용되었으며, 관광객을 대상으로 한 인터뷰를 통해 연구 결과를 보충하였다. 이와 관련한 문헌 자료, 대구의 역사, 그리고 Daegu 2011의 추진 배경을 검토한 결과, 본 논문은 세 가지 항목으로 도출되었다. 첫째, 비판 담론 분석(critical discourse analysis)을 통해 대회와 관련된 홍보 비디오를 분석한 결과 대구시는 세계 관광 시장에서 차지하는 대구의 지위에 대하여 불확신한 것으로 나타났다. 둘째, 관광지로서 대구의 위상에 대한 대구시 자체의 불확신은 홍보 비디오 이외의 다른 홍보물 분석에서도 여전히 나타났다. 이런 홍보물들은 대구시의 이미지와 미래를 향한 염원에 부담을 초래하였다. 셋째, 이런 논의를 확장시킨 결과 홍보물에서 보여지는 대구의 관광 경관은 실제 보여지는 경관과 부분적으로 차이가 나타나고 있었다. 이것으로 볼 때, 세계선수권대회는 대구시에 긍정적인 효과를 창출함과 동시에 앞으로 세계적인 도시로서의 위상을 확립하기 위해서 해결해야 할 과제를 남기고 있다.

• 전자공학회논문지
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• 제52권5호
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• pp.33-47
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• 2015

셀룰러 네트워크에서 기지국의 과부하를 줄이고 주파수 부족 현상을 완화시킬 수 있는 D2D(Device-to-Device) 통신에 대한 연구가 활발히 진행되고 있다. 하지만 셀룰러 네트워크의 상향링크 주파수 자원을 공유함으로써 상호간의 간섭은 증가하게 된다. 본 논문에서는 셀룰러와 D2D 사이의 간섭을 줄이기 위하여 새로운 하이브리드 수신기 FSC(Full Suppression Cancellation)를 제안한다. 제안한 수신기는 IRC(Interference Rejection Combining)와 SIC(Successive Interference Cancellation)를 결합하여 간섭을 억제 및 제거 할 수 있다. 시스템 레벨 시뮬레이션은 3GPP LTE-A 시스템의 20MHz 대역을 기반으로 이루어 졌으며, 시뮬레이션 결과 제안한 수신기를 통해 기존 수신기보다 SINR, 전송률 및 스펙트럼 효율 측면에서 성능 향상을 가져다주는 것을 확인하였다.

• 한국지역사회생활과학회지
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• 제13권2호
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• pp.37-51
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• 2002

This study was performed to investigate the degree of different stresses and to search the influence of food habit and nutrient intakes at stress situation in university students and secondary school teachers. The data was collected by questionnaire method and searched nutrient intakes by 24 hours recall. The subjects were 282 students and 152 high school teacher in Kyunggi do. Physical status was no difference with two groups. Energy intake of teachers was lower than that of students, but the intakes of vitamin A and C were high in teachers' group. The university students had more stress situation than teachers in almost kind of stresses except overload stress. Self-diagnosed dietary habits were better in the group of teacher. Especially smoke and alcohol drink behavior were correlated with nutrient intakes in male teachers and students. The quantity of nutrient of nutrient intakes was correlated with different kind of stress. The stress of life event was correlated with the intakes of carbohydrate, minerals, thiamin and riboflavin, and the deprivation was with iron and vitamin A in teachers' group. The intake of almost nutrients was correlated with the stress of noise in students' group. By the analysis of stepwise multiple regression, although the $R^2$ values were very low, vitamin C intake was influenced in the factor at the stress of life events($R^2$=0.025), self-efface($R^2$=0.030) and noise($R^2$=0.020), thiamin was at food induced stress ($R^2$=0.021) and vitamin A was at the stress of type A behavior($R^2$=0.022) and anxiety response($R^2$=0.014). Therefore, we could concluded that different kind of stresses were influenced in dietary behavior and nutrient intakes. More research would be needed at the aspects of health promotion in the stressful situation of modern society.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.208-213
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• 1995

The vehicle navigation system is developed for helping driver to retrieve driving information more easily and lastly. Navigation System informs driver many pieces of driving information - roadway structure and system, on-line traffic condition, the position of vehicle, route guidance, destination and other infor- mation service. As the style of information is diverse and the amount of information is large, driver may have mental and visual overload. The display of information can disturb the driver's attention and this can cause accidents. This state is caused by the defect of human-machine interactions. When the navigation system is designed, human factors - cognitive, judgment, operating -must be considered. The display style must be designed simply and easily, not to be obstacle of human - machine interface. In this study, outside- in view display style and inside-out view display style are compared each other. Tow factors are measured. One is cognitive factor-time of cognition on information that is displayed by screen display, cognition error rate. The other is image of screen display - subject's feeling about several styles of display, degree of subject's preference. The prototype of roadway is four kinds -Cross, T-cross and O-cross. Roadway display for test is taken from paper maps. Traffic condition display style, vehicle position display style and route guidance display style are taken from current display style. Traffic condition display style is symbol. vehicle position display style and route guidance display style are described as color and symbol. The test on screen display is implemented doing given tasks. Then the test is analyzed statistically. The result of test analysis gives the guideline to the designer for the map display of the vehicle navigation system.

• 한국정보통신학회논문지
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• 제4권3호
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• pp.537-548
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• 2000

ATM은 다양한 전송속도의 트래픽을 통계적으로 다중화하여 효과적으로 수용할 수 있는 경제적인 정보 전달 방식이다. 그러나 일시적인 과부하시 큰 셀 손실 및 셀 지연이 발생할 수 있다. 따라서 사용자 관점에서 서비스 품질 보장과 망 관점에서 이용 효율의 극대화라는 상반된 내용에 대해서 효과적인 트래픽 제어와 망 자원관리가 요구된다. 본 논문에서는 ATM스위치 네트워크를 2단을 기본으로 구성하였을 때 혼합되어진 각 서비스 클래스에 대한 서비스 품질을 보장하기 위하여 ATM Forum에서 권고하는 반응제어 기법인 BP(Back Pressure) 방법과 pushout 메커니즘을 혼합한 POBP(PushOut BP) 방법을 제안하였다. 제안한 방법에서는 대역폭의 사용 현황을 실 시간적으로 정확하게 파악하여 협정이 이루어 져야 한다. 이러한 과정을 통하여 잔여 대역폭을 효과적으로 사용할 수 있을 뿐만 아니라 공정한 대역폭의 사용을 보장하여 2단 ATM 네트워크에서의 폭주 상태로 인한 셀 손실률을 개선할 수 있었다.

• 한국융합학회논문지
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• 제8권8호
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• pp.105-114
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• 2017

본 연구는 임상 간호사 개인이 지각하는 환자관련 스트레스와 직무탈진의 관계에서 직무환경이 미치는 융합적 상호작용을 확인하기 위해 시도되었다. 본 연구의 대상자는 서울소재 상급종합병원에 근무하는 168명의 간호사였으며 자료는 2014년 7월 1일부터 15일까지 편의표집 되었다. 구조화된 설문지로 환자관련 스트레스, 직무환경, 직무탈진을 측정하였다. 연구결과 환자관련 스트레스는 직무탈진을 증가시키고 있었다. 환자관련 스트레스와 직무탈진의 관계에서 직무환경 요인의 역할을 분석한 결과 업무부하가 낮을수록 그리고 통제감, 보상, 공정성, 가치가 높을수록 환자관련 스트레스가 직무탈진에 미치는 부정적 영향이 감소하는 조절효과를 보여주었고, 커뮤니티는 직무탈진을 낮추는 주효과를 보여주었다. 이상의 연구결과로 볼 때 간호사의 직무탈진 완화를 위해 병원 차원의 직무환경 개선전략이 필요할 것으로 보인다.