• International Journal of Reliability and Applications
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• v.7 no.1
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• pp.27-39
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• 2006

Many real world cases in material failure analysis do not follow perfectly the normal distribution. Forcing of the normality assumption may lead to inaccurate predictions and poor product quality. We examine the failure process of the internal bond (IB or tensile strength) of medium density fiberboard (MDF). We propose a forced censoring technique that closer fits the lower tails of strength distributions and better estimates extremely smaller percentiles, which may be valuable to continuous quality improvement initiatives. Further analyses are performed to build an accelerated common-shaped Weibull model for different product types using the $JMP^{(R)}$ Survival and Reliability platform. In this paper, a forced censoring technique is implemented for the first time as a software module, using $JMP^{(R)}$ Scripting Language (JSL) to expedite data processing, which is crucial for real-time manufacturing settings. Also, we use JSL to automate the task of fitting an accelerated Weibull model and testing model homogeneity in the shape parameter. Finally, a package script is written to readily provide field engineers customized reporting for model visualization, parameter estimation, and percentile forecasting. Our approach may be more accurate for product conformance evaluation, plus help reduce the cost of destructive testing and data management due to reduced frequency of testing. It may also be valuable for preventing field failure and improved product safety even when destructive testing is not reduced by yielding higher precision intervals at the same confidence level.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.98-104
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• 2009

The objective of this study was to characterize quality changes of PET-packaged green tea beverage during 4-week storage at $60^{\circ}C$. Changes in oxygen transmission of the PET bottle package and cap removal torque were also examined. MXD6 blend PET bottle showed stability in the gas barrier. Its cap removal torque was kept stable during the 4 weeks. pH, color value, contents of vitamin C and catechin showed significant changes during the storage while caffeine and amino acid did not change significantly. Four alcohol flavor components (hexanol, linalool, menthol, and ${\alpha}$-terpineol) increased rapidly during the first three weeks while d-limonene did not show significant change. Sensory test showed decrease in astringent flavor lowering the product flavor and acceptability.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.74-74
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• 2010

모바일 정보통신기기를 중심으로 전자패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있는 추세이다. 플립칩 패키징 접합소재로는 솔더, ICA(Isotropic Conductive Adhesive), ACA(Anisotropic Conductive Adhesive), NCA(Non Conductive Adhesive) 등과 같은 다양한 접합소재가 사용되고 있다. 최근에는 언더필을 사용하는 플립칩 공법보다 미세피치 대응성을 위해 NCP를 이용한 플립칩 공법에 대한 요구가 증가되고 있는데, NCP의 상용화를 위해서는 공정성과 함께 신뢰성 확보가 필요하다. 본 연구에서는 LDI(LCD drive IC) 모듈을 위한 COF(Chip-on-Film) 플립칩 패키징용 NCP 포뮬레이션을 개발하고 이를 적용한 COF 패키지의 신뢰성을 조사하였다. 테스트베드는 면적 $1.2{\times}0.9mm$, 두께 $470{\mu}m$, 접속피치 $25{\mu}m$의 Au범프가 형성된 플리칩 실리콘다이와 접속패드가 Sn으로 finish된 폴리이미드 재질의 flexible 기판을 사용하였다. NCP는 에폭시 레진과 산무수물계 경화제, 이미다졸계 촉매제를 사용하여 다양하게 포뮬레이션을 하였다. DSC(Differential Scanning Calorimeter), TGA(Thermogravimetric Analysis), DEA(Dielectric Analysis) 등의 열분석장비를 이용하여 NCP의 물성과 경화거동을 확인하였으며, 본딩 후에는 보이드를 평가하고 Peel 강도를 측정하였다. 최적의 공정으로 제작된 COF 패키지에 대한 HTS (High Temperature Stress), TC (Thermal Cycling), PCT (Pressure Cooker Test)등의 신뢰성 시험을 수행한 결과 양산 적용 가능 수준의 신뢰성을 갖는 것을 확인할 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.347-356
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• 2015

A study has been conducted numerically to investigate the lifted flat syngas flame structure of impinging jet flame configuration with the global strain rates in 10% hydrogen content. In this study, the effects of strain rate were major parameters on chemistry kinetics and flame structure at stagnation point. The numerical results were calculated by SPIN application of the CHEMKIN package. The strain rates were adjusted with Reynolds numbers of premixed syngas-air mixture. Different flame shapes were observed with different strain rates. As strain rate has increased, the flame temperature and axial velocity have been decreased due to the flame heat loss increment, and the OH radical reaction zones become narrower but each mole fractions are still constant. Also, the reversion of $H_2O$ product near stagnation point has been found out when strain rate has increased. This phenomenon is attributed to the rapid production of oxidizing radical reaction such as the R12 ($H+O_2(+M)=HO_2(+M)$), which makes the R18 ($HO_2+OH=O_2+H_2O$) reaction increment.

• Journal of Korean society of Dental Hygiene
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• v.18 no.5
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• pp.797-806
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• 2018

Objectives: The purpose of this study was to analyze Influence of stress on oral health and quality of life. Methods: The participants were 172 students from 4 universities located in DaeJeon, South Korea. A questionnaire was administered, assessing the impacts of the general characteristics of the participants, temporomandibular joint (TMJ) symptoms, xerostomia, and halitosis on stress. And oral impacts on daily performance were also investigated. Data were analyzed using the Statistical Package for the Social Sciences 18.0. Results: The level of stress was higher in female, and the causes of stress was reported scholastic achievement, relations with professors, get a job. The students who were higher stress were more conscious of TMJ symptoms, xerostomia and halitosis(p<0.05). Stress was significantly positively correlated with TMJ symptoms (r=0.376, p<0.001), dry mouth (r=0.360, p<0.001), and bad breath (r=0.343, p<0.001). Oral Impacts on Daily Performance (OIDP) scores were significantly positively correlated with dry mouth, bad breath, TMJ symptoms, and stress. Regression analysis showed that 54.5% of the independent variables were related to OIDP scores. Stress and TMJ symptoms exerted a significant effect on OIDP scores. Conclusions: Stress among university students affects oral health and quality of life. Stress coping mechanisms and oral health care education programs should be developed and applied at universities.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1075-1083
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• 2016

Nowadays, the use of wireless input devices has been increasing on the basis of high convenience and portability. In particular the most widely used wireless keyboard and the mouse to use the 2.4 GHz frequency band, but due to the third party receives the electromagnetic wave from leaking when the radio equipment it is easy to obtain the personal information and the vulnerability is also being reported consistently. In this paper, implement a system to analyze and manipulate the packets of 2.4 GHz wireless keyboard and mouse using USRP device and GNU Radio package for verify the vulnerability of 2.4 GHz wireless keyboard and mouse. Using the construction system has attained a equipment specific address and key information by analyzing the communication protocol and the packet structure of the device was proved that a user can operate the PC to send the random key from long distance.

• Korean Journal of Health Education and Promotion
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• v.15 no.1
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• pp.1-30
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• 1998

A study on skin care was conducted in order to develop proper skin care program and disseminate the Information to the consumers. The study was performed from October 2, 1997 though April 30 1997 by using questionnaires. The subjects were 1,793 from lug cities of Seoul, Pusan and, and 800 from medium and small cities of Kyongsan, Kimchon, Mokpo and KimHae cities. All subjects were females over 20 years. 1. 64.3% of the subjects said that they chose the massage packs after considering their skin condition. 55.1% of the subjects said that they did not know the side effects of the massage packs. 2. 53.3% of the subjects reported that they knew the cause of acne. and 73.3% of the respondents reported that they knew the nature of their body classified by oriental medicine. 3. The average knowledge and attitude was 10.61 :t3.46%( who it is converted to percent, it is 53.1%). The upper limit was 18.9% and lower limit was 19.0%. 4. The factors which are under the influence on knowledge of skin care were the times of massage, education level, the height of subjects, disease of skin, age, the degree of fatty body, the hour of make-up(R2=0.137). 5. The factors which are under the influence on the times of massage were education level, the experience of skin side effect, the status of physic8I health and the birth place of the subjects(R2=0.139). 6. The main factors which had significant effect on the status of face skin health were the status of physical health, economic status, age, the side effect of skin cosmetic, and the hour of make-up(R2=0.140). 7. Finally, it is recommended that training package on side effect of cosmetics, massage, physical characteristics and proper way of make-ups, and the public should be educated on the above mentioned areas.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.3
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• pp.73-85
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• 2002

The purpose of this study was to develop prediction models for plant species abundance by stream restoration. Generally the stream plant is affected by stream gemophology. So in this study, the relationship between the vegetation abundance and stream gemophology was developed by multiple regression analysis. The stream characteristics utilized in this study were longitudinal slope, transectional slope, micro-landforms through the longitudinal direction, riparian width and geometric mean diameter and biggest diameter of bed material, and cumulated coarse and fine sand weight portion. The Pyungchang River with mountainous watershed and the Kyungan stream and the Bokha stream in the agricultural region were selected and vegetation species abundance and stream characteristics were documented from the site at 2~3km intervals from the upper stream to the lower. The Models for predicting the vegetation abundance were developed by multiple regression analysis using SPSS statistics package. The linear relationship between the dependant(species abundance) and independant(stream characteristics) variables was tested by a graphical method. Longitudinal and transectional slope had a nonlinear relationship with species abundance. In the next step, the independance between the independant variables was tested and the correlation between independant and dependant variables was tested by the Pearson bivariate correlation test. The selected independant variables were transectional slope, riparian width, and cumulated fine sand weight portion. From the multiple regression analysis, the $R^2$for the Pyungchang river, Kyungan stream, Bokga stream were 0.651, 0.512 and 0.240 respectively. The natural stream configuration in the Pyungchang river had the best result and the lower $R^2$for Kyunan and Bokha stream were due to human impact which disturbed the natural ecosystem. The lowest $R^2$for the Bokha stream was due to the shifting sandy bed. If the stream bed is fugitive, the prediction model may not be valid. Using the multiple regression models, the vegetation abundance could be predicted with stream characteristics such as, transection slope, riaparian width, cumulated fine sand weigth portion, after stream restoration.

• Journal of the Korean Home Economics Association
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• v.40 no.9
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• pp.127-141
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• 2002

This research aims to examine the influence of facilitative communication between mother and high school daughter on daughter's perceived family cohesion, family adaptability, and satisfaction of mother's working or non-working status. In order to verify statistically the research questions above, experimental tools were made for each variable, and Cluster Sampling with Stratification was conducted among high school girls in Seoul. A total of 670 questionnaire sheets were administered to 13 high schools for girls in December 2001, and only 501 sheets were used for data analysis. The SPSS 10.0 package was used for factor analysis, reliability analysis, multiple regression analysis. The following results were obtained: 1) Mother-high school daughter's facilitative communication significantly influences daughter's perceived family cohesion. In general, mother-high school daughter's facilitative communication had R square of 27.6% with regards to daughter's perceived family cohesion. 2) Mother-high school daughter's facilitative communication significantly influences daughter's perceived family adaptability. In general, mother-high school daughter's facilitative communication had R square of 25.3% with regards to daughter's perceived family adaptability. 3) Mother-high school daughter's facilitative communication significantly influences daughter's perceived satisfaction of mother's working of non-working status. In general, mother-high school daughter's facilitative communication had R square of 24.0% with regards to daughter's perceived satisfaction of mother's working status, and 7.4% with regards to non-working status.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.242-242
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• 2006

Increasingly complex tasks are performed by computers or cellular phone, requiring more and more memory capacity as well as faster and faster processing speeds. This leads to a constant need to develop more highly integrated circuit systems. Therefore, there have been numerous studies by many engineers investigating circuit patterning. In particular, PCB including module/package substrates such as FCB (Flip Chip Board) has been developed toward being low profile, low power and multi-functionalized due to the demands on miniaturization, increasing functional density of the boards and higher performances of the electric devices. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. The imprint technique. is one of promising candidates, especially due to the fact that the expected resolution limits are far beyond the requirements of the PCB industry in the near future. For applying imprint lithography to FCB, it is very important to control thermal properties and mechanical properties of dielectric materials. These properties are very dependent on epoxy resin, curing agent, accelerator, filler and curing degree(%) of dielectric materials. In this work, the epoxy composites filled with silica fillers and cured with various accelerators having various curing degree(%) were prepared. The characterization of the thermal and mechanical properties wasperformed by thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheometer, an universal test machine (UTM).