• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.213-218
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• 2004

As optical fiber communication grows, the fiber alignment become the focus of industrial attention. This greatly influence the overall production rates for the opto-electric products. We proposed multi-axis nano positioning stage for optical fiber alignment. This device has 3 DOF translation and sub nanometer resolution. This nano stage consist of 3 PZT-driven flexure stages which are stacked parallel. The displacement of it is measured with capacitance gauge and is controlled by computer-embedded main controller. The design process of flexure stage using FEM is proposed and the performance evaluation of this system is verified with experiments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1238-1247
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• 2003

Simplified thermodynamic analysis of high pressure 4-stage reciprocating compressors with 4 inter-coolers has been investigated to predict a behavior of a compressor system for NGV(natural gas vehicles). A computer program has been developed to predict and estimate the performance of high pressure 4-stage reciprocating compressor system. Thermodynamic properties of compressed natural gas(CNG) were calculated by ideal gas theory and compression cycle was assumed as reversible adiabatic compression and expansion processes, and isobaric intake and discharge processes. Comparison between results predicted by calculation model and measured by experimental tests is presented.

• Progress in Superconductivity
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• v.1 no.2
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• pp.105-109
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• 2000

We have designed and fabricated a single-flux-quantum(SFQ) four-stage shift register using YBCO bicrystal Josephson junctions, and tested its operations using a digital measurement set-up. The circuit consists of 4 shift register stages and a read SQUID placed next to each side of the shift register. Each SQUID was inductively coupled to the nearby shift register stage. The major obstacle in testing the circuits was the interference between the two read SQUIDs, and we could get over the problem by determining the correct operation points of the SQUID from the simultaneously measured modulation curves. Loaded data ('1' or '0') were successfully shifted from a stage to the next by a controlled current pulse injected to the bias lines located between the stages, and the corresponding correct data shifts were observed with the two read SQUIDs.

• Journal of the korean academy of Pediatric Dentistry
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• v.3 no.1
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• pp.7-11
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• 1976

The author measured the degree of development and the eruption pattern of first permanent molars with orthopantomography in 553 Korean children(male; 302, female; 251) from 4 to 9 years old. The orthopantomographs were obtained from dept. of pedodontics, college of dentistry, Seoul National University. The results of the studies were as follows: 1. Upper first permanent molars were erupted with distal inclination of about 30 degrees in the early stage and they gradually moved in the mesial direction by bodily movement of the tooth to be in contact with the disto-proximal surface of primary secondary molars in the late stage. 2. Lower first permanent molars were erupted with mesial inclination in the early stage and moved mesially by tipping movement of the tooth to be in contact with the disto proximal surface of the second primary molars in the late stage. 3. The eruptive forces were considered to be main etiologic factors of space closure after the premature loss of primary molars.

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.37-41
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• 2007

Recently PZT is used in ultra precision mechanism field. PZT has a small motion range although it has a high resolution. Many methods, such as inchworm, impact driving, etc., have been applied for the expansion of the motion range.? In this study, the new actuating mechanism for rotational motion with two PZT actuators is proposed. The ultra precision rotational actuator which is made by proposed mechanism is able to operate both coarse and fine motion. The design parameters of the proposed mechanism are considered to improve the performance of the system. The rotational stage which is applied by the proposed mechanism is fabricated. The resolution and velocity for fabricated rotational stage are measured by laser interferometer.

• Journal of Integrative Natural Science
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• v.12 no.1
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• pp.9-13
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• 2019

Recently, as the sleep disorder problem of modern people deepens, the interest towards quality of sleep is increasing. To increase the quality of modern people's sleep. This paper has suggested an LED lighting control system according to the sleep stage using PPG sensors of wearable devices. The pulse of the wrist radial artery was measured using a wearable device mounted with PPG sensor, which enables heart rate-measuring, and by using the point that heart rate lowers during stable sleep than non-sleeping, the LED lighting of indoors was controlled, which is the disturbing element when sleeping. For the performance evaluation, a 10-Fold cross analysis was conducted for performance evaluation, and a result of an average accuracy 87.02% was obtained as a result. Therefore, the LED lighting control system according to the sleep stage using a wearable device of this paper is expected to contribute to raise the quality of the user's life.

• The Journal of Advanced Prosthodontics
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• v.6 no.2
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• pp.126-132
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• 2014

PURPOSE. This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability. MATERIALS AND METHODS. Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (${\alpha}$=0.05). RESULTS. The postload removal torque value was high in the following order with regard to magnitude: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05). CONCLUSION. The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.

• Korean Institute of Interior Design Journal
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• v.25 no.5
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• pp.42-54
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• 2016

The purpose of this study is to provide a reference for stage planning by analyzing current state of major theaters' stage space and understanding feedback from directors belonged to theaters. Each room in total 18 theaters' stage facilities was measured and their usage and requirements were analyzed on the spot. In addition, each director provided their experiential knowledge about appropriate stage composition for musical performance. The findings are as follow: under stage machinery is not needed for musical. Tour teams prefer to use their own show-deck for set conversion. On the other hand, over stage flying system needs to be able to deal with dense, fast, and accurate scene change. The size and location of the motor room needs to be carefully considered. The number of set battens is directly linked up with the size of the motor room, which should be located lower than the gridiron. As stage sets get bigger and complicated, the number of works at the gridiron is also increasing. The grating floor has to have enough strength coping with machines lifting heavy sets. Most sound control for musical performance is being done at F.O.H. these days rather that in the sound control room. It should equip enough work area and related infra especially for tour teams. 1st gallery needs to have enough effective width, power infra for lighting fixture, and strong guardrail. Lastly, the whole process of parking-unloading-transporting equipments and sets from loading dock to stage and vice versa needs to be efficient, and this has to be carefully considered from early stage of planning.

• Journal of Korean Academy of Nursing
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• v.28 no.4
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• pp.970-979
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• 1998

Cancer has been considered a life-threatening disease and coping patterns could have a strong impact the physical and psychological health of patients and their family. The purpose of this study was to identify the change of coping patterns according to the phases of illness in the patients with cancer and their family caregivers and to compare the coping patterns of patients with those of their caregivers. The phases of illness consisted of 1st(initial) stage, 2nd(metastatic or recurred) stage and 3rd (terminal) stage based on literature. The coping methods were measured using the modified Ways of Coping Questionnaire by Lazarus & Folkman(1984). Seventy-nine patients(35 in stage 1, 31 in stage 2, and 13 in stage 3) and ninety-two caregivers (38 in stage 1, 30 in stage 2 and 24) agreed to participate from two general hospitals in Seoul and Choongnam. No significant changes were found in the coping patterns according to the phases of illness in both groups. Patients in stage 2 and caregivers in stages 2 and 3 problem-focused coping methods were significantly used more than emotion-focused coping methods. Patients in stage 1 significantly used two coping strategies that were cognitive reconstruction and emotion expression more than caregivers. Patients in stage 2 significantly used emotion-focused coping methods including minimizing threat, blame, and emotion expression excepting wishful thinking more than caregivers. We need more research to identify the relationship between the coping methods and their efficiencies through longterm observation and attempt to develope the nursing interventions that could have an improvement on positive coping methods and provide guidance on the problems the patients experience.

• Korean Journal of Adult Nursing
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• v.16 no.2
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• pp.191-201
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• 2004

Purpose: Many studies have shown that regular exercise produces positive effects on health. The purpose of this study was to examine the differences of health-related quality of life by stage of exercise and the interaction effect of age, sex and stage of exercise. Method: A total of 1266 participants were interviewed with structured questionnaire. Stage of exercise was assessed with a single item and respondents were classified with respect to exercise intention and behavior. Health-related quality of life was measured with SF-36 Health Survey Questionnaire. Result: Health-related QOL were found to be different by stage of exercise. The subjects who were reached maintenance stage showed significantly higher scores on physical functioning, bodily pain, general health perception, mental health, role limitation due to emotional problems, social functioning, and vitality than those in preparation, contemplation, and precontemplation stage. In addition a significant interaction effect between stage of exercise and age was found on physical functioning, bodily pain, general health perception, mental health, and vitality. Conclusion: Perceived health-related QOL varies with stage of exercise. This finding suggests that health is related to both intention and behavior of exercise. Therefore it is important to consider cognitive-motivational and behavioral stage of change for developing exercise programs.