• 소성∙가공
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• 제7권2호
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• pp.158-167
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• 1998

Hot restoration mechanism flow stress and stain of the Al2024 composites reinforced with 1,8,15,36, and $44{\mu}m\;SiC_p$(10 vol. %) were studied by hot torsion tests. The hot restoration mechanism of all the composites was found to be dynamic recrystallization(DRX) at $320^{\circ}C$ while that of the composites reinforced with 1 and $8{\mu}m\;SiC_p$ was found to be dynamic recovery(DRX) at $480^{\circ}C$. It was found that the Al2024 composite with $15{\mu}m\;SiC_p$ showed the highest flow stress(${\sim}$223 MPa) at $320^{\circ}C$ under a strain rate of 1.0/sec. Also the highest flow strain of the composites was obtained at $430^{\circ}C$. The com-posites reinforced with 1 and $8{\mu}m\;SiC_p$ showed lower flow stress and higher flow strain at $480^{\circ}C$ than those of the composites reinforced with 15, 36, and $44\;{\mu}m\;SiC_p$ These result were discussed in relation to the transition of the hot restoration mechanism. $DRX{\leftrightarrow}DRV$. The dependence of flow stress on strain rate and temperature was attempted to fit with the hyperbolic sine equation ($\dot{\varepsilon}=A[sinh({\alpha}{\cdot}{\sigma}_p]^n$ exp(-Q/RT)and Zener-Hollomon parameter($Z=\;\dot{\varepsilon}\;exp(Q/RT))$.

• Asian-Australasian Journal of Animal Sciences
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• 제25권2호
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• pp.286-290
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• 2012

The majority of laboratory animals were transported from commercial breeders to a research facility by ground transportation. During the transportation, many biological functions and systems can be affected by stress. In this experiment, the change of body weight during the transportation was measured and the recovery periods from the transportation stress established based on the body weight changes. Total 676 laboratory animals which were aged between 3 to 9 wk old were studied. The transportation time taken from container packing to unpacking the container was approximately 24 h. The temperature of animal container was constantly maintained by air-conditioning and heating equipment. Rats were found to be more sensitive than mice. The body weight of rats was significantly decreased 3.71% (p<0.05) compared to the body weight of mice which decreased 0.9% There was no significant difference between the strains in the same species. When the changes of body weights were compared between delivery days, C57BL/6 mice showed the most variable changes compared to other species and strains. Consequently, C57BL/6 was more sensitive to stress than the other strains and the transportation process needs to be standardized to reduce between day variability. To establish the recovery periods from transportation stress, the body weight changes were measured during the acclimation period. Although the body weight of animals decreased during transportation, animals recovered their weight loss after the next day.

• 전력전자학회논문지
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• 제21권1호
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• pp.10-18
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• 2016

In this study, an efficient clamp is proposed to reduce the switch voltage stress of a forward converter. The proposed clamp consists of a conventional LC snubber, a tertiary winding, and a diode. When the switch is turned OFF, the magnetizing inductor energy of the transformer is recovered directly into the flyback output, which is the tertiary winding and diode network, instead of circulating in the LC snubber. Therefore, switch voltage stress and circulating current caused by the magnetizing inductor energy are reduced. This condition improves the efficiency of the forward converter with limited switch voltage stress. A theoretical analysis and the design guidelines of the proposed converter are provided. Experimental results are also reported.

• Steel and Composite Structures
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• 제31권1호
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• pp.43-51
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• 2019

This paper is concerned with the numerical calculation of mixed-mode stress intensity factors (SIFs) of 2-D isotropic functionally graded materials (FGMs) by the natural element method (more exactly, Petrov-Galerkin NEM). The spatial variation of elastic modulus in non-homogeneous FGMs is reflected into the modified interaction integral ${\tilde{M}}^{(1,2)}$. The local NEM grid near the crack tip is refined, and the directly approximated strain and stress fields by PG-NEM are enhanced and smoothened by the patch recovery technique. Two numerical examples with the exponentially varying elastic modulus are taken to illustrate the proposed method. The mixed-mode SIFs are parametrically computed with respect to the exponent index in the elastic modulus and external loading and the crack angle and compared with the other reported results. It has been justified from the numerical results that the present method successfully and accurately calculates the mixed-mode stress intensity factors of 2-D non-homogeneous functionally graded materials.

• 대한간호학회지
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• 제5권2호
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• pp.29-37
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• 1975

The purpose of this study was to measure the extent of stress existing in hospitalized patients which might play an important part in delaying recovery of patients. The study was conducted July l0th through 16th, 1975; a total of 146 patients from 2 general hospitals in Seoul were sampled. Questionnaire, formulated by the researcher, were used to gather necessary information concerning stress in accordance with the physical, psychological, economical and social variables. Data were analysed by mean stress score, and the significances were tested by Critical Ratio. The results were as follows ; 1. No significant difference was revealed in accordance with sex, however, male patients showed higher stress scores on the economic variables. 2. No. significant difference was apparent in accordance with marital status, however, the unmarried showed a tendency of higher stress scores at all variables. 3. Significant difference was revealed between the age group of 35-49 years and that of over 50 years; the age group of 18-34, and 35-49 years showed higher stress scores. 4. No. significant difference was revealed in accordance with previous experience of hospitalization, however, the group with previous experience tends to show higher stress scores in all variables. 5. No significant difference was revealed in accordance with the types of admission, however, group admitted on emergency showed higher stress scores compared to the group admitted plained in advance at social and economic variables. 6. No significant difference was revealed in accordance with the length of hospitalization, however, tendencies were apparent that the longer the length of hospitalization, the lower the mean stress scores.

• 서비스연구
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• 제6권4호
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• pp.1-13
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• 2016

서비스 분야에서 감정노동은 서비스 실패로 이어지는 경우가 많다. 기업 등 조직의 관리자들은 감정노동으로 인한 스트레스 등 부정적인 효과를 줄여서 서비스 회복으로 이어지게 할 수 있다. 본 연구의 목적은 감정노동과 관련된 선행요인 및 후행요인들이 서비스 회복과 어떠한 관련성을 가지고 있는지 알아보기 위하여 수행되었다. 연구목적을 위해 특히 현장에서 일하는 일선 직원들을 대상으로 데이터를 수집하였다. 이후 통계도구 등을 이용하여 실증적으로 가설을 분석하고 그 결과를 나타내었다. 연구결과는 다음과 같다. 첫째, 표면 행위는 서비스 회복에 부정적으로, 내면 행위는 서비스 회복에 긍정적으로 영향을 미쳤다. 둘째, 권한위임과 동기부여는 서비스 회복에 긍정적인 영향을 미치고 있었다. 셋째, 서비스 회복으로 인해 이직의도가 유의하게 낮아지는 효과를 거두는 것을 알 수 있었다. 결론적으로 현장 직원들의 감정노동과 근무환경에 대한 대처방법을 적절히 시행함으로써 서비스 회복 성과를 높이고 이직의도를 낮출 수 있을 것이다.

• 기본간호학회지
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• 제5권1호
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• pp.107-124
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• 1998

Based on King's goal attainment theory, this research deals with applying nursing intervention of mutual goal settings to gastrectomy patients. It tests the effects of nursing intervention, according to the patients' health locus of control, suggested as external boundary criteria for the theory by employing a quasi-experimental design which consists of a pretest-posttest non-equivalent control and experimental groups. The subjects of this research were 62 gastrectomy patients hospitalized at Y medical center and the experimental and control groups consisted of 31 subjects. The experimental group received nursing intervention at the mutual goal setting of 5 times from the day before the surgery to the 5th day after the surgery, while the control group received only routine nursing care. Recovery indicators of both groups were measured and compared. Measurement variables included patients' characteristics, health locus of control, forced vital capacity, forced expiratory volume in one second, peak expiratory flow, bowel movement recovery, mobility recovery, level of pain, patients' stress and patients' satisfaction. Data were analyzed using SPSS statistical package and the hypotheses were tested by ANOVA and ANCOVA. Results of the analyses are summarized as follows : 1) Internal health locus of control had higher effects of the nursing intervention of mutual goal setting than external health locus of control on pulmonary ventilatory functions of forced vital capacity, forced expiratory volume in one second, and peak expiratory flow. 2) There was no statistically significant difference in the effects of nursing intervention of mutual goal setting on the bowel movement recovery between the internal and external health locus of control. 3) There was no statistically significant difference in the effects of nursing intervention of mutual goal setting on the mobility recovery between the internal and external health locus of control. 4) There was no statistically significant difference in the effects of nursing intervention of mutual goal setting on the level of pain between the internal and external health locus of control. 5) There was no statistically significant difference in the effects of nursing intervention of mutual goal setting on the level of stress between the internal and external health locus of control. 6) There was a statistically significant difference in the effects of nursing intervention of mutual goal setting on the level of satisfaction with provision of nursing information between the internal and external health locus of control, and there was no statistically significant difference in the effects of nursing intervention of mutual goal setting on the level of satisfaction with outcome of nursing between the internal and external locus of control. On the basis of the research results, the following are recommended : 1) Repeated research on responses to health locus of control is necessary. 2) Not only the effectiveness of nursing intervention in acute recovery periods, but also the long term effects are to be investigated. 3) The development of instruments is needed to accurately measure mutual goal setting regarding postoperative deep breath, coughing, early ambulation, etc. so that the relationship among the postoperative recovery indicators may be explored. 4) It is required that an instrument be developed to measure perception which facilitates goal attainment in the interactive setting between patients and nurses.

• 한국기계연구소 소보
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• 통권19호
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• pp.53-60
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• 1989

Hot upsetting experiments were carried out on presintered steel powder preforms in the temperature range 700- $950^{\circ}C$ to examine the hot deformation behavior. Following conclusions were drawn on the basis of the present study. -The flow stress during hot deformation is directly related to $\alpha$- $\gamma$ phase trasformation - The flow stress of ferrite is lower than that of austenite in the moderate temperature range 800- $900^{\circ}C$ for most alloys used in the present study - Major restoration behavior during hot deformation in the ferrite range is dynamic recovery.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 봄 학술발표회 논문집
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• pp.329-330
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• 2003

In general, the thermoplastic elastomers have the elastic recovery property caused by phyical crosslinks after the stress is applied. Segmented block copolyetheresters also have been used as elastomers. Many$\^$l-2/ tried to improve the elastic recovery of those which are less elastic than polyurethane. We confirmed that the copolyetherester based on poly(2,6-butylene naphthalate)(PBN) ha.4 segment had the high melting temperature, whcih was useable at the broader temperature range and the one based on poly(1,3-trimethylene terephthalate)(PTT) the high crystallinity, which would be expected to get the high elastic recovery. (omitted)

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.251-255
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• 1997

The conventional high frequency phase-shifted full bridge dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free type high frequency soft switching phase-shifted full bridge (FB) dc/dc converter with energy recovery snubber (ERS) attached at the secondary side of transformer. The energy recovery snubber (ERS) adopted in this study is consisted of three fast recovery diode(Ds1, DS2, Ds3), two resonant capacitor (Cs1, Cs2)