• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.611-616
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• 2010

This study investigated the characteristics of fracture behavior and mode on solder joints before and after thermal shock test for automotive application component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as lead-free solder. The shear strength was decreased with thermal cycle number, after 432 cycles of thermal shock test. In addition, fracture mode was verified to ductile, brittle fracture and base materials fracture such as different kind fractured mode using SEM and EDS. Before the thermal shock, the fractured mode was found to typical ductile fracture in solder layer. After thermal shock test, especially, Ag was found on fractured portion as roughest surface. Moreover, it occurred delamination between a PCB and a Cu land. Before thermal shock test, most of fractured mode in solder layer has dimples by ductile fracture. However, after thermal shock test, the fractured mode became a combination of ductile and brittle fracture, and it also could find that the fracture behavior varied including delamination between substrate and Cu land.

• Journal of Korean Academy of Nursing
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• v.50 no.1
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• pp.52-65
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• 2020

Purpose: To examine the effects of a smartphone application-based exercise program on self-efficacy expectations (SEE) and outcome expectations regarding exercise (OEE), physical fitness, activity level, physiological indices, and health-related quality of life in a sample of hemodialysis patients. Methods: A quasi-experimental control group pre-test post-test design was used. Subjects were recruited from two university hospitals in G city. The subjects were assigned randomly by coin toss: 33 participants to the experimental group and 30 to the control group. A literature review and the self-efficacy theory were used to develop the smartphone program. Experts designed and verified the program to be userfriendly and in consideration of user interaction. Data were collected through a self-report pre-test post-test questionnaire and online medical records. Results: In the experimental group, the levels of physical fitness and physical activity were significantly improved post-test, but the scores on health-related quality of life and the physical indices did not improve. In the experimental group, the SEE and OEE post-test scores were also significantly higher than the pre-test scores, but the control group's scores did not change. Conclusion: The smartphone application-based exercise program based on self-efficacy theory significantly improved the level of physical fitness and activity, SEE, and OEE for hemodialysis patients. The use of this application-based exercise program for hemodialysis patients might be an effective nursing intervention tool for improving SEE, OEE, level of physical fitness, and physical activity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.393-399
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• 1997

This study is concerned with reliability technology. In order to achieve the quality level of items for consumer's satisfaction, tests for the item's reliability are essential. This article deals with a method and real field application to plan reliability testing. Especially the environmental conditions and methods such as screening test for electronic components will be shown. As well, we will explore methods and field applications with respect to mechanic destructive tests and non destructive tests.

• Journal of the Korean Statistical Society
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• v.30 no.2
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• pp.281-290
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• 2001

Symmetric estimation and recursive mean adjustment are considered to construct tests for the doble unit root hypothesis for both parametric and semiparametric time series models. It is shown that simultaneous application of symmetric estimation and recursive mean adjustment yields the most powerful test. Moreover, size property of the semiparametric test based on the simultaneous application is bet among all semiparametric tests.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2063_2064
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• 2009

Recently, load circuits and components of customer are various. Therefore failures of ELB(Earth Leakage Breaker) and MCCB(Molded case circuit breakers) are more frequent. Lite time of MCCB even if there is same units differ from environment, condition of operation. FEMCA is a efficiency method of system operation or maintenance for system reliability. We study on FMECA procedures and method. In this paper, we focused on FMECA application to MCCB life time test.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.737-742
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• 1998

Non-destructive field tests of the concrete has achieved increasing acceptance for the evaluation of existing concrete structures. But the application of this test has not still accomplished to guarantee perfectly the durability of the concrete bridges in Korea. As two major testing methods, this paper recommends the proper empirical relationship between the rebound number together with the ultrasonic pulse velocity and the core strength. Also, this paper recommend the relationships as the aging and as the element.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.10a
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• pp.101-106
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• 1990

To estimate the concrete strength at fresh state is very important problem in quality control. So, this study is designed for analyzing the quality control application of practical use Re-Mi-Con with the early estimation method of concrete strength using the test of solution heat of hydrochloric acid.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.153-165
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• 2003

This paper considers the likelihood ratio test statistic based on nonlinear regression quantiles estimators in order to test of hypothesis about the regression parameter $\theta_o$ and derives asymptotic distribution of proposed test statistic under the null hypothesis and a sequence of local alternative hypothesis. The paper also investigates asymptotic relative efficiency of the proposed test to the test based on the least squares estimators or the least absolute deviation estimators and gives some examples to illustrate the application of the main result.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.182-189
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• 2004

The application of adhesively bonded components is increasing in various industries such as automobile, aircraft, IC packages, and soldering techniques. In spite of such wide application in adhesively bonded components, nondestructive test techniques applying to adhesively bonded components have not been clearly established yet. In this paper, characteristics of ultrasonic test on interfaces of adhesively bonded components have been investigated by calculating transmission coefficient theoretically and experimentally. From the experimental results, the optimum conditions to establish frequencies for adhesively bonded homogeneous and dissimilar components are 4∼6 MHz and 2∼4 MHz, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.179-183
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• 2005

In apply roof waterproof system using of synthetic high polymer sheet for rooftop measure physical performance (tension$\cdot$tearing ability, temperature relativity, heating stretch performance, junction performance, wind resistance test) by various test environment condition waterproof test of structure and performance of construction work aspect, present suitable form of construction work under these environment. Also, wish to improve durability of concrete structure as that examine in priority about adhesion method and joint junction method with waterproof out surface, and present new direction about roof system application of waterproofing method for rooftop.