• Journal of the Microelectronics and Packaging Society
• /
• v.18 no.2
• /
• pp.35-41
• /
• 2011

Recently, board level solder joint reliability performance of IC packages during drop impact becomes a great concern to semiconductor and electronic product manufacturers. The handheld electronic products are prone to being dropped during their useful service life because of their size and weight. The IC packages are susceptible to solder joint failures, induced by a combination of printed circuit board (PCB) bending and mechanical shock during impact. The board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this paper, applying the JEDEC (JESD22-B111) standard present a finite element modeling of the FBGA. The simulation results revealed that maximum stress was located at the outermost solder ball in the PCB or IC package side, which consisted well with the location of crack initiation observed in the failure analysis after drop reliability tests.

• Corrosion Science and Technology
• /
• v.8 no.3
• /
• pp.116-118
• /
• 2009

Korea Institute of Construction Materials founded Seosan Outdoor Exposure Test Site 2005 at Korea, which is a part of Worldwide Exposure Network (WEN). To evaluate the test site along with other exposure test sites, three different types of paints have been under real time weathering conditions at three major weathering test facilities around the world. Using these test specimens several spectroscopic experiments along with physical tests have been performed. Also acceleration tests have been performed using the same paints. The correlation of weathered paints among three different test facilities and accelerated test results has been compared. From the results the reliability of Seosan Weathering Test Facility and reasonable life time prediction tests are discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.6
• /
• pp.307-312
• /
• 2015

The sandwich panel is commonly used domestically because it's less costly and easier to handle. But fires have frequently occurred in buildings employing sandwich panels, such as the fires in Eecheon cold storage and in Gwangju Pyungdong industrial zone. Sandwich panels with steel plates on their surface prevent fire water from penetrating to the fire source, which makes it difficult to extinguish a fire in a timely manner. Toxic gas generated from some insulation material leads to serious loss of life and property. This study is intended to develop an extinguishing system for sandwich panels, thereby reducing the fire risk. Fire water and volume were determined in the wake of the study on the structure of a sandwich panel extinguishing system, and improvement and testing of the fire characteristics of the sandwich panel. Based on such study and test, a fire model test was conducted. Consequently, the sandwich panel with extinguishing system was proven to have a reduced fire risk, compared to traditional or fire retardant panels.

• Journal of Information Technology Applications and Management
• /
• v.23 no.4
• /
• pp.117-125
• /
• 2016

Software reliability in the software development process is an important issue. In infinite failure non-homogeneous Poisson process software reliability models, the failure occurrence rates per fault. can be presented constant, monotonic increasing or monotonic decreasing pattern. In this paper, the reliability software cost model considering decreasing intensity function was studied in the software product testing process. The decreasing intensity function that can be widely used in the field of reliability using power law process, log-linear processes and Musal-Okumoto process were studied and the parameter estimation method was used for maximum likelihood estimation. In this paper, from the software model analysis, we was compared by applying a software failure interval failure data considering the decreasing intensity function The decreasing intensity function model is also efficient in terms of reliability in the arena of the conservative model can be used as an alternating model can be established. From this paper, the software developers have to consider life distribution by preceding information of the software to classify failure modes which can be gifted to support.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.8 no.4
• /
• pp.9-14
• /
• 2008

Ubiquitous implementation of indoor location-based technology is recognized that one of the important elements of the technology. Specifically, the hospital management of patients, the silver-town management, the implementation of the smart home for the indoors rather than outdoors in a range of broadband users for location-aware technology is needed. This paper in wireless devices with an indoor location awareness shows about the system's technical design and implementation. Location-based technology for wireless LAN users aware of the strength of radio signals (Received Signal Strength Indication, RSSI) using trilateration. Topographic mapping system will be implemented wireless devices and servers, Access Point (AP), which is the system's development and testing throughout the physical environment to determine the potential for real-life applications.

• Journal of Korean Academic Society of Home Health Care Nursing
• /
• v.10 no.2
• /
• pp.141-147
• /
• 2003

The purpose of this study was to develop and apply a Web-based Nursing Education & Instruction Program to help the clinical nurses improving their knowledge and skills of ostomy care. This program was developed in three different steps: analysis. design. and development. The results of the study were as follows: The analysis step was designed to select the study contents for effective and easy educationthrough the analyses of specialized books. This surveyed and analyzed study contents were categorized into five different sections. Introduction. ostomy classification. ostomy management. elimination management. and life style. After that each section describes necessary information of each category. In the design step. the image files used in this program were created using Adobe Photoshop 6.0. and HTML files were designed and developed using Namo Editor 5.0. In the development step. the developed program was published into Web using FTP (File Transfer Protocol) and then finalized after trial operation for testing of real users. In addition. this Web-based Nursing Education & Instruction Program will be used as excellentand effective tool for continuous and lifelong education in nursingfield. In this study. computer-aided education program was developed for ostomy management and managed at the Web-Server (http://hshong.knu.ac.kr/ostomy) in order to help nurses real-time education in clinical field by this program.

• Convergence Security Journal
• /
• v.12 no.6
• /
• pp.3-10
• /
• 2012

In this paper, make a study decision problem called an optimal release policies after testing a software system in development phase and transfer it to the user. When correcting or modifying the software, finite failure non-homogeneous Poisson process model, considering learning factor, presented and propose release policies of the life distribution, log linear type model which used to an area of reliability because of various shape and scale parameter. In this paper, discuss optimal software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement. In a numerical example, the parameters estimation using maximum likelihood estimation of failure time data, make out estimating software optimal release time.

• Carbon letters
• /
• v.7 no.3
• /
• pp.196-200
• /
• 2006

Graphite has hexagonal closed packing structure with two bonding characteristics of van der Waals bonding between the carbon layers at c axis, and covalent bonding in the carbon layer at a and b axis. Graphite has high tolerant to the extreme conditions of high temperature and neutron irradiations rather than any other materials of metals and ceramics. However, carbon elements easily react with oxygen at as low as 400C. Considering the increasing production of today of hydrogen and electricity with a nuclear reactor, study of oxidation characteristics of graphite is very important, and essential for the life evaluation and design of the nuclear reactor. Since the oxidation behaviors of graphite are dependent on the shapes of testing specimen, critical care is required for evaluation of nuclear reactor graphite materials. In this work, oxidation rate and amounts of the isotropic graphite (IG-110, Toyo Carbon), currently being used for the Koran nuclear reactor, are investigated at various temperature. Oxidation process or principle of graphite was figured out by measuring the oxidation rate, and relation between oxidation rate and sample shape are understood. In the oxidation process, shape effect of volume, surface area, and surface to volume ratio are investigated at $600^{\circ}C$, based on the sample of ASTM C 1179-91.

• Journal of Information Technology Applications and Management
• /
• v.21 no.1
• /
• pp.107-136
• /
• 2014

This study aims to suggest research implications that may contribute to preventing turnover of personnel in small and medium sized software companies. A research model is developed based on the Bergiel, et al. (2009) and Woo and Hwang (2010). This model describes how human resource management (HRM) practices (compensation, recognition, job autonomy, technical capability development, work-life conflict) affect turnover intention, through the mediating effects of job satisfaction and job embeddedness. 177 questionnaires are collected and analyzed. Validity and reliability of measures, and appropriateness of the structural model are verified. Results of the hypotheses testing are somewhat different from the expected ones: Only compensation and technical capability development are significant, but the remaining variables are not significant in affecting job satisfaction and job embeddedness. As for turnover intention, job embeddedness and job satisfaction are proved to be significant predictors. From the analyses of data, subsequent interview with several respondents and additional data analyses, more research implications are derived. The study has a limitation of not including more diverse variables that might affect job embeddedness and job satisfaction of so called road warriors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.11
• /
• pp.729-735
• /
• 2016

It is highly important issue to use an energy efficiently for sustainable prosperity of mankind. From this point of view, using LED lighting can be a good alternative because it has a lot of advantages such as high efficiency, long life time and eco-friendly manufacturing process. That is the reason why using LED lighting has been encouraged worldwide. However, in situations that LED lighting is replacing traditional lighting quickly, the problem of the flicker of LED lighting has emerged as an important issue. Therefore, in foreign countries like US or Japan in order to ensure the reliability of LED lighting, study for flickering effects of the human body and test methods are have been actively conducted. But related research in domestic situation is an insufficient condition. In this study, a flicker characteristic was measured conventional lamps such as incandescent lamps or fluorescent lamp and 81 items of LED lightings which are distributed in domestic markets.