• 대한예방한의학회지
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• 제9권2호
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• pp.93-106
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• 2005

A survey was performed for 2 weeks in October 2004 in order to examine the effects and changes of far infrared and anion of office workers aged 40 and older before and after wearing the underwear. In the survey, questionnaires and photoplethysmography were used to measure the difference between the two tests conducted with one week interval. The findings could be summed up as follows: 1. There was no statistically significant difference in changes of vascular aging points and photoplethysmogram wave form before and after wearing the far infrared and anion underwear but the points showed the increasing tendency(p>0.05). 2. A statistically significant difference was confirmed since the total points of each item in the questionnaires increased after wearing the underwear(p<0.001). 3. In connection with the systemic symptoms, a significant difference was found with increased points in all items except for no. 6 after wearing the underwear(p<0.05). 4. With regard to the difference before and after wearing the underwear depending on the Kidney symptoms, there was a significant difference with increased points in all items except for item no. 1 after wearing the underwear(p<0.05). In conclusion, to put on the underwear with effect of far infrared and anion is believed to smooth metabolism and blood circulation, contributing by thus to promoting health and preventing disease. Further studies with wider sampling of subjects are requested to diversify and refine the findings from this sectional study.

• 대한전기학회논문지:전력기술부문A
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• 제53권4호
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• pp.214-220
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• 2004

This paper describes a busbar current differential relay in conjunction with a current transformer(CT) compensating algorithm irrespective of the level of the remanent flux. The compensating algorithm detects the start of first saturation if the third-difference function of the current exceeds the threshold; it estimates the core flux at the first saturation start by inserting the negative value of the third-difference function of the current into the magnetization curve; thereafter, it calculates the core flux during the fault and compensates the distorted current using the magnetization curve. The algorithm estimates the correct secondary current irrespective of the level of the remanent flux and needs no saturation point of the magnetization curve. The proposed relay can improve not only security of the relay on an external fault with CT saturation but sensitivity of the relay on an internal fault; the relay can improve the operating speed on n internal fault with CT saturation. This paper concludes by implementing the relay into a digital signal processor based prototype relay.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.154-159
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• 2004

A new finite difference scheme is studied fur the simulation of free surface, surface the third derivative tenn for the wave elevation is artificially added in the the free-surface boundary condition. This study presents a comparative analysis with simulations performed by using the classical MAC method. More systematic computations are carried out by changing the submergence depth and angle of attack. Through the numerical simulation, it is found that a new numerical method becomes more efficient for the reason that the free surface elevation is reasonably developed at tire rear of trailing edge.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권4호
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• pp.214-214
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• 2004

This paper describes a busbar current differential relay in conjunction with a current transformer(CT) compensating algorithm irrespective of the level of the remanent flux. The compensating algorithm detects the start of first saturation if the third-difference function of the current exceeds the threshold; it estimates the core flux at the first saturation start by inserting the negative value of the third-difference function of the current into the magnetization curve; thereafter, it calculates the core flux during the fault and compensates the distorted current using the magnetization curve. The algorithm estimates the correct secondary current irrespective of the level of the remanent flux and needs no saturation point of the magnetization curve. The proposed relay can improve not only security of the relay on an external fault with CT saturation but sensitivity of the relay on an internal fault; the relay can improve the operating speed on n internal fault with CT saturation. This paper concludes by implementing the relay into a digital signal processor based prototype relay.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.85-92
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• 2003

When a current transformer (CT) is saturated, the wave-shape of the secondary current is distorted and contains points of inflection, which correspond to the start or end of each saturation period. Discontinuity in the first-difference function of the current arises at points of inflection, where the second and third differences convert into pulses that can be used to detect saturation. This paper describes the design and evaluation of a CT saturation detection technique using the third-difference function and includes the countermeasure for a spike signal. Test results clearly demonstrate that the algorithm successfully detects the start and end of each saturation period irrespective of the remanent flux and magnetization inductance in the saturated region. This paper concludes by describing the results of hardware implementation of the algorithm using a DSP.

• 한국가정과학회지
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• 제7권2호
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• pp.97-113
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• 2004

This study was to investigate the relationship between parent attachment, peer support and behavior problems of middle school students. The subjects were 591 male and female students in the first and third grade of the middle school and their mothers in Busan. The instruments used for this study were Inventory of Parent Attachment Scale, Peer Support Scale and Behavior Checklist for Adolescents. The results were as follows: 1. The first grade students had stronger attachment on father and mother than third grade. The third grade students had perceived peer support more than first grade. Female students had stronger attachment on mother and perceived peer support more than male students. And there was no significant sex difference in attachment on father. In the case of female students, internalizing and externalizing behavior problems increased grade. But, in the case of male students, there was no grade difference in internalizing and externalizing behavior problems. In the case of first grade students, there was no sex difference in internalizing behavior problems. In the case of first grade students, males had more externalizing behavior problems than females. But in the case of third grade students, females had more externalizing behavior problems than males. 2. As parent's education level was higher, students had stronger attachment on parents and perceived more peer support. As family income was higher, students had stronger attachment on father and perceived more peer support. 3. In case of female students, parent attachment and peer support were correlated negatively with internalizing and externalizing behavior problems. In case of male students, attachment on fathers and peer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.859-863
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• 1987

In this paper, a relationship between difference triangular sets and sum triangular sets is developed to evaluate the weighted number of the third-order intermodulation products. In addition, a lower bound of the intermodulation products falling into the worst signal channel has been derived using the relationship between difference triangular sets and sum triangular sets. The formulas of the lower bound are useful for estimating the intermodulation impairment level in satellite communication systems.

• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.399-412
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• 1992

The purpose of this study was to evaluate the root canal transportation and remaining dentin / cementum thickness after using hand and ultrasonic instrumentation in the curved mesial root canals of extracted human mandibular molars. Fourty - six clear polyether blocks were made and randomly divided into two groups: hand instrumentation group with K - Flex files and ultrasonic instrumentation group with Suprasson SP unit. All root canals were instrumented to a size corresponding to a # 30 K - Flex file 1mm short from the radiographic apex. The roots were then sectioned perpendicular to the long axis so the apical and middle third could be evaluated with the Zoom stereomicroscope. The results were as follows : 1. In the total amount of removed dentin at middle third level, there was not significant difference between the hand instrumentation and ultrasonic instrumentation (P>0.05). 2. In the total amount of removed dentin at apical third level, there was more removed by the ultrasonic instrumentation than hand instrumentation(P<0.005). 3. In the transportation width, there was not significant difference between the two groups at both sectioned levels(P>0.05). 4. It was suggested that the canal was transported distally at middle third level and mesially at apical third level by booth techniques.

• 핵의학기술
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• 제14권1호
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• pp.73-77
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• 2010

핵의학 기술학의 발전은 많은 변화를 가져왔다. 하드웨어적인 발전이 많이 있었고 또한 소프트웨어의 발전도 핵의학 기술학 발전에 지대한 공을 세웠다. 소프트웨어의 발전으로 그 동안 수동으로 설정해야 했던 많은 ROI를 자동으로 설정할 수 있게 되었다. automated ROI가 manual ROI와 어떠한 정량분석의 차이를 가지고 있는지 알고자 한다. 분석은 3가지의 분석을 통해 결론을 도출하고자 하였다. 분석 1은 신장 automated ROI와 신장 manual ROI를 비교하였다. 분석 2는 threshold의 크기변화에 따른 차이를 조사하였다. 육안적 판단으로 신장의 외곽선보다 큰 threshold ROI(이하 A threshold), 외곽선과 일치하는 threshold ROI(이하 B threshold), 외곽선보다 작은 threshold ROI(이하 C threshold)를 설정하여 신장의 기능 값을 구하여 이를 비교 하였다. 분석 3은 automated background ROI를 세 가지 full, half, quarter로 분류하여 이에 따른 기능값의 차이를 분석하였다. 분석 1에서 신장 automated ROI와 신장 manual ROI간에 통계적으로 유의한 차이는 보이지 않았다. 그러나 분석 2에서 C threshold는 각 A threshold와 B threshold 간에 유의한 차이 (p<0.01)를 보였다. 분석 3은 분석 1을 통해 얻어진 결론을 토대로 시행되었다. 각 3가지 형태의 background에서 full background가 통계적으로 유의한 차이를 보였다(p<0.05). automated ROI가 manual ROI와 유의한 차이를 보지 않아 입증된 결과는 사용자의 편의와 객관성이 증대될 것으로 기대된다. 분석 2에서는 신장의 외곽선보다 작게 설정된 threshold는 신장의 외곽선보다 크게 설정된 threshold보다 큰 오차를 가질 수 있다는 것을 예상할 수 있다. 분석 3은 신장 주변의 간과 비장에 background가 증가되어 초래된 결과로 예상한다.

• 대한치과기공학회지
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• 제18권1호
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• pp.15-25
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• 1996

This study is to measure and compare the hardness and tensile strength of each time after we recast seven times continually only with and metal alloy Chromium-Cobalt alloy used in the production of partial denture frame work. The result of the experiment were as follow; 1) The result of the hardness measurement The result of the first casting was $490.48{\pm}38.38$ and that of the second recasting was $455.18{\pm}35.61$ and form the third recasting. the result were $518.38{\pm}37.68$ and over. The change of the hardness difference between each recasting was as follow; The hardness difference between the first casting and the second recasting was $35.25{\pm}31.93$ and that between the second recasting and the third recasting was $63.20{\pm}54.02$. There was a statistically significant difference(P<0.01) in the above hardness, however, there was little difference on the whole. And after the third recasting, the hardness grew high a little bit. That is why low-melting metals such as Cr, Mn, Cu of alloy ingredient was evaporated or there was an effect of changes in metal crystal structure, I suppose. 2) The result of the tensile strength measurement. There was a statistically significant difference(P<0.01) between the first casting and the second, the fourth recasting, however. there was little difference in general.