• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.454-464
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• 1987

The objective of this research is to analyze and evaluate the dynamic flow curve of metals under impact loading at both high strain rate (.epsilon.=1/h dh/dt > 10$\^$3/m/s/m) and large strain (.epsilon.=In h/h$\_$0/ > 1.0). A test method for dynamic compression of metal disc is described. The velocity of the striker face and the force on the anvil are measured during the impact period. From these primitive data the axial stress, strain, and strain rate of the disc are obtained. The Strain rate is determined by the striker velocity divided by the specimen height. This gives a slightly increasing strain rate over most of the deformation period. Strain rates of 100 to 10,000 per second are achieved. Attainable final strains are 150%. A discussion of several problem areas is presented. The friction on the specimen surfaces, the determination of the frictional coefficient, the influence of the specimen geometry (h$\_$0//d$\_$0/ ratio) on the friction effect, the lock-up condition for a given configuration, the friction correction factor, and the evaluation of several lubricants are given. The flow function(stress verus strain) is dependent on the material condition(e.g., prior cold work), specimen geometry, strain rate, and temperature.

• Journal of Plant Biotechnology
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• v.29 no.1
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• pp.25-29
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• 2002

The study was carried out to establish an efficient protocol for shoot organogenesis and plant regeneration from stem explant cultures of Lycopersicon esculentum cv. Micro-Tom. The regenerated shoots obtained from stem explant cultures on solid MS medium containing the different concentrations of BAP. The highest number of shoots (5.3) per explant and shoot growth (0.7 cm) was obtained on MS medium containing 4.0 mg/L BA. The additions of AgNO$_3$ and putrescine substantially improved the shoot regeneration frequency, at the optimal concentration of 7 mg/L and 50 mg/L respectively. The regenerated shoots (about 1 cm) were normal and could be easily rooted with 0.1 mg/L IBA treatment. The rooted plants were hardened and transferred to vermiculite with a 92% survival rate where they grew normally.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1158-1174
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• 1988

A numerical technique is developed for the solution of fully developed turbulent recirculating flow in the passage of variable area using the non-orthogonal coordinate transformation. In the numerical analysis, primitive pressure-velocity finite difference equations were solved by SIMPLER algorithm with 2-equation turbulence model and algebraic stress model (ASM). QUICK scheme on the differencing of convective terms which is free from the inaccuracies of numerical diffusion has been applied to the variable grids and the results compared with those from HYBRID scheme. In order to test the effect of streamline curvatures on turbulent diffusion Lee and Choi streamline curvature correction model which has been obtained by modifying the Leschziner and Rodi's model is testes. The ASM was also employed and the results are compared to those from another turbulence model. The results show that difference of convective differencing schemes and turbulence models give significant differences in the prediction of velocity fields in the expansion region and outlet region of the combustor, however show little differences in the parallel flow region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.223-229
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• 2015

In this study, the effects of the leakage flow between the baffle and tube bundles on the performance of a shell and tube heat exchanger (STHE) were examined using the commercial software ANSYS FLUENT v.14. A computational fluid dynamics model was developed for a small STHE with five different cases for the ratio of the leakage cross-sectional area to the baffle cross-sectional area, ranging from 0 to 40%, in order to determine the optimum leakage flow corresponding to the maximum outlet temperature. Using fixed tube wall and inlet temperatures for the shell side of the STHE, the flow and temperature fields were calculated by increasing the Reynolds number from 4952 to 14858. The present results showed that the outlet temperature, pressure drop, and heat transfer coefficient were strongly affected by the leakage flow, as well as the Reynolds number. In contrast with a previous researcher's finding that the leakage flow led to simultaneous decreases in the pressure drop and heat transfer rate, the present study found that the pertinent leakage flow provided momentum in the recirculation zone near the baffle plate and thus led to the maximum outlet temperature, a small pressure drop, and the highest heat transfer rate. The optimum leakage flow was shown in the case with a ratio of 20% among the five different cases.

• Journal of Korean Library and Information Science Society
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• v.46 no.3
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• pp.225-253
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• 2015

This study investigated the interactions between archives and users based on content analysis of posts of Facebook and Twitter operated by archival institutions. It focused on posts in official Facebooks and Twitters of the U.S. and the U.K. national archives. The posts included 66 in Facebook and 670 in Twitter of the U.S. national archives, as well as 73 in Facebook and 84 in Twitter of the U.K. national archive. The analysis showed that information sharing of in-house collections and online resources, as well as information dissemination of events were the most common interaction types of the posts. 1 and 1 communication or information gathering such as questionnaire or vote rarely happened. In addition, the extent of users' responses was great on posts regarding information sharing of in-house collections. Providing information about people or events with timely manners motivated interests and participations of users. It is necessary to consider various types of interactions that facilitate user engagement. It is also important to make efforts to provide timely records in connection with exiting web resources and a variety of social media provided by archival institutions.

• 한국사회복지학회:학술대회논문집
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• 2000.04a
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• pp.561-579
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• 2000

The purpose of this study is to grope for the improving the management in order that Korea community centers may put better welfare services to community residents. Community welfare center is a professional social welfare agency that meets welfare needs of community residents by offering synthetical and various welfare services in community according to social, economical, cultural, regional background. Community welfare center was established for clearing up the conflict between social classes after Industrial Revolution in England, for solving problems of women movement and immigration in America, for different purpose in other countries. But there is no difference between countries in the sense of welfare services activities centering around poor community though each purpose are different. It can be known that community center must perform the function as social welfare professional agency which aimed at community care program. Resource which are needed for management of community center are mostly in community and community center must strive to get resources which are in community. But all the weakness of finance and facility which community center has may not be solved by using community resources. Community welfare center is not fixated yet in Korea. And community residents has little understanding of community center. Thus national financial support is needed. Actually community has difficulty to mobilize community resource. The problem is how to carry out this national financial support effectively and going on study about this problem is needed.

• Journal of Navigation and Port Research
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• v.34 no.3
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• pp.195-203
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• 2010

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely cohesive soft soil is applied to the self-propelled miner. Hinged and ball constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, self-propelled miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-${\beta}$ method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• Korean Journal of Health Education and Promotion
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• v.26 no.5
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• pp.97-113
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• 2009

Objectives: This study was conducted to identify the intervention effects on health efficacy and health knowledge related to health behaviors for improving cardiovascular health in elementary school children. Methods: A repeated measure, pre-post-test design was used to identify the intervention effect on health efficacy and health knowledge among 5th grade school children. Intervention consisted of a curriculum classroom intervention and parent intervention. Health efficacy, health knowledge, and perceived parental monitoring were measured for testing intervention effect. A sample of 219 participants completed a baseline pre-test and two tests during intervention and after intervention from March to July 2004. Results: Mental health efficacy improved significantly from baseline test to the test after intervention (F = 32.88, p < 0.0001). Physical health efficacy also significantly increased during intervention (F = 50.51, p < 0.0001), but did not significantly change after parent intervention. Health knowledge increased significantly from baseline test to the test after education (F =10.23, p < 0.0001), but decreased after parent intervention. Perceived parental monitoring had a significant impact on mental health efficacy and physical health efficacy. Conclusion: The findings support school-based cardiovascular health promotion intervention as effective in improving health efficacy and health knowledge. Parental influence should also be considered to maintain improved health efficacy and health knowledge by thinking process in the intervention for elementary school children.

• 한국노년학
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• v.29 no.2
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• pp.425-440
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• 2009

The purpose of this study was to understand the ability of the elderly to activity of daily living, assess their quality of sleep and level of depression at home and analyze how such relate health related quality of life. The subject was 223 senior over 65 years old who lived in B Metropolitan City. Descriptive statistics, independent t-test, one-way ANOVA, Pearson correlation and stepwise multiple regression were performed using SPSS WIN 14.0. The major findings of this study are as follow: 1) 34.1% of the respondents experienced a degree of sleep disorder and 57.8% were vulnerable to depression. 2) Activity of daily living, quality of sleep and depression were related to health related quality of life to a statistically significant degree. quality of sleep, activity of daily living positively related to health related quality of life. level of depression related to health related quality of life. Stepwise multiple regression analysis revealed the most powerful predictor of health related quality of life was depression. While age, level of education and quality of sleep were also found as significant predictor variables. Based on these results, it is necessary to perform more studies on health related quality of life and related factors according to that in various settings. Especially, to develop a program intended to improve the health related quality of life of the elderly at home, we need to consider not only physical factors but also psychological factors.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.579-590
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• 2006

1. 연구배경 교원질 분해작용을 하는 호중구의 세포질 효소인 기질금속단백분해효소-8은 치주질환, 류마티스 관절염, 그리고 궤양결장염과 같은 염증성 질환에서 농도가 증가한다고 알려져 있다. 최근에는 A. actinomycetemcomitans의 leukotoxin이 사람호중구에서 기질금속단백분해효소-8의 분비를 유도하는 것이 보고되었다. 이 연구의 목적은 선천면역 체계에서 세포표면 항원무리14, Toll-like 수용기, 그리고 $NF-{\kappa}$ B경로를 통하여 A. actinomycetemcomitans의 지질다당질로 유도된 기질금속단백분해효소-8의 분비 여부와 세포기전을 알아보고자 하였다. 2. 연구재료 및 방법 건강한 개인 제공자(남자 13명, 여자 3명)로부터 얻은 개개인의 20ml 말초혈액을 제조사의 지침에 따라 호중구를 추출한 후 항세포표면 항원무리14와 함께 $4^{\circ}C$에서 30분간 전배양 한 후, $37^{\circ}C$에서 9시간 동안 배양시켰다. 추출한 호중구에 Toll-like 수용기 억제제 또는 $NF-{\kappa}$ B억제제인 TPCK를 첨가한 후 $37^{\circ}C$에서 1시간 동안 전배양하고 $37^{\circ}C$에서 9시간 동안 배양시켰다. 호중구에 세포뼈대 억제제인 cholchicine, nocodazole, demecolcine, 그리고 cytochalasin B를 A. actinomycetemcomitans의 지질다당질과 함께 $37^{\circ}C$에서 9시간 동안 배양시켰다. 기질금속단백분해효소-8 분비량은 효소면역측정법을 통해 결정하였다. 통계처리는 일원배치 분산분석법을 이용하였다(p<0.05). 3. 결과 A. actinomycetemcomitans 지질다당질은 기질금속단백분해효소-8의 분비를 증가시켰다. 기질금속단백분해효소-8의 분비는 항세포표면 항원무리14에 의해서 억제되었지만, 항 Toll-like 수용기2, 항 Toll-like 수용기4 항체는 억제시키지 못했다. $NF-{\kappa}$ B 억제제는 A. actinomycetemcomitans의 지질다당질로 유도된 $NF-{\kappa}$ B 결합 활성도와 기질금속단백분해효소-8 분비를 억제하였다. 미세섬유 중합반응 억제제는 A. actinomycetemcomitans의 지질다당질로 유도된 기질금속단백분해효소-8의 분비를 억제시켰으나, 미세관 중합반응억제제는 억제시키지 못했다. 4. 결론 위의 연구결과를 종합하여 볼 때, 기질금속단백분해효소-8은 A. actinomycetemcomitans의 지질다당질로 유도되며, 세포표면 항원무리-$NF-{\kappa}$ B 경로를 통하여 분비되고, 이 분비 과정은 미세섬유 계통이 관여하는 것으로 보인다.