• 공업화학
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• 제35권2호
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• pp.148-153
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• 2024

In this study, a methodology for evaluating impact strength in rollable devices was developed, focusing on measuring impact strength and evaluating rolling and unrolling durability simultaneously, with findings reported from tests on a real demonstration unit. The study utilized a flexible and rollable polyimide (PI) substrate for the evaluations. The chosen parameters for this methodology were a flat-type impactor, weights of 300 g, 500 g, and 1000 g, a rolling shaft ranging from 30 R to 5 R, and the positioning of the impactor. The results revealed that the difference in defect rates when comparing the 300 g and 500 g weights was minimal. However, the adoption of a 1000 g weight markedly increased the defect count due to damage to the PI film's surface. Furthermore, an uptick in rolling and unrolling cycles led to more pronounced surface scratches on the PI film. These methods and findings are poised to make a substantial contribution towards refining reliability testing for a wide array of rollable device applications, including smartphones, watches, pads, and wearable technology.

• 한국정밀공학회지
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• 제29권6호
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• pp.654-663
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• 2012

Damage induced by low velocity impact loading in aircraft composite is the form of failure which is frequently occurred in aircraft. As the consequences of impact loading in composite laminates, matrix cracking, delamination and eventually fiber breakage for higher impact energies can be occurred. Even when no visible impact damage is observed, damage can exist inside of composite laminates and carrying load of the composite laminates is considerably reduced. The objective of this study is to evaluate and predict residual strength behavior of composite laminates by impact loading and for this, tensile test after impact was carried out on composite laminates made of woven CFRP.

• 한국통신학회논문지
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• 제40권9호
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• pp.1678-1685
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• 2015

본 논문에서는 신뢰도를 모르는 불완전한 채널 정보를 이용해 빔포밍 기법의 장점과 직교 시공간 블록 코딩 (Orthogonal Space-Time Block Coding, OSTBC) 기법의 장점을 결합해 주는 선형 프리코딩 기법을 제안한다. 먼저 다양한 값의 채널 정보의 신뢰도를 가정한 상태에서 각 신뢰도가 프리코딩 성능에 미치는 영향을 분석한다. 그 뒤, 효율적인 프리코더의 설계를 위하여 수신 SNR을 바탕으로 필요한 채널 정보의 신뢰도를 예측하는 방법을 제안한다. 시뮬레이션을 통해 제안된 프리코더 설계 기법의 효율성을 확인한다.

• International Journal of Reliability and Applications
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• 제12권2호
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• pp.123-129
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• 2011

Due to restriction of vehicle emissions and high demand for fossil fuels nowadays, car manufacturers around the world are looking into alternative ways in introducing new car model that would vastly captured the market. Thus, Electric Vehicle (EV) has been further developed to take the advantage of the current global issues on price of fossil fuels and impact on the environment. Since car battery plays the crucial role on the overall performance of EV, many researchers have been working on improving the component. This paper focused on the reliability of EV battery which involves recognizing failure types, testing method and life prediction method. By focusing on these elements, the reliability feature being identified and as a result the batteries life will be prolonged.

• Computers and Concrete
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• 제6권1호
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• pp.79-93
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• 2009

In the present paper, a methodology has been presented for the reliability assessment of concrete barriers that lie at a certain depth in the soil, and a missile (a rigid projectile) impacts the top of the soil cover normally, and subsequently after penetrating the soil cover completely it hits the barrier with certain striking velocity. For this purpose, using expressions available in the literature, striking velocity of missile at any depth of soil has been derived and then expressions for the depths of penetration in crater and tunnel region of concrete barrier have been deduced. These depths of penetration have been employed for the derivation of limit state functions. Using the derived limit state functions reliability assessment of underground concrete barrier has then been carried out through First Order Reliability Method (FORM). To study the influence of various random variables on barrier reliability, sensitivity analysis has also been carried out. In addition, a number of parametric studies is conducted to obtain the results of practical interest.

• 한국콘텐츠학회논문지
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• 제13권12호
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• pp.235-245
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• 2013

본 연구는 노인의 사회자본이 자존감과 심리적 복지감에 미치는 영향이 어떠한지를 살펴보고자 하였고, 이를 위해 부산에 소재하는 65세 이상의 노인 162명을 상대로 분석한 결과는 다음과 같다. 노인의 사회자본과 심리적 복지감에서는 공적신뢰가 높다고 인식할수록, 규범이 낮다고 인식할수록 그리고 여성 노인이 남성 노인보다 심리적 복지감이 더 높은 것으로 나타났다. 노인의 사회자본과 자아존중감의 관련성에서는 공적신뢰, 공식적 네트워크, 규범이 자아존중감에 유의미한 정적 영향을 미치는 것으로 나타났으며, 여성이 남성보다 자아존중감이 더 높은 것으로 나타났다. 이러한 연구결과를 토대로 연구의 함의를 논의하였으며, 추후 연구과제와 연구의 한계를 논의하였다. 특히 본 연구는 국내 최초로 노인의 사회자본과 자존감 및 심리적 복지감의 관련성을 실증적으로 파악하였다는 점에서 의의가 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권1호
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• pp.463-468
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• 2013

Background: Body image dissatisfaction among breast cancer survivors has been associated with psychological stress resultant from breast cancer and resultant surgery. This study aimed to examine the psychometric properties of the Malay Version of the Breast-Impact of Treatment Scale (MVBITS) and to investigate the associations of retained factors with the Hospital Anxiety and Depression Scale (HADS) and the Rosenberg Self-Esteem Scale (RSES). Materials and Methods: The MVBITS was 'forward-backward' translated from English to Malay and then administered to 70 female breast cancer patients who came to the Oncology Clinic of University Malaya Medical Centre, Kuala Lumpur, Malaysia to undergo chemotherapy. Principal component analysis (PCA) with varimax rotation was performed to explore the factor structure of the MVBITS. Associations of retained factors were estimated with reference to Spearman correlation coefficients. Results: The internal consistency reliability of MVBITS was good (Cronbach's alpha 0.945) and showed temporal stability over a 3-week period. Principal component analysis suggested two factors termed as 'Intrusion' and 'Avoidance' domains. These factors explained 70.3% of the variance. Factor 1 comprised the effects of breast cancer treatment on the emotion and thought, while Factor 2 informed attempts to limit exposure of the body to self or others. The Factor 1 of MVBITS was positively correlated with total, depression and anxiety sub-scores of HADS. Factor 2 was positively correlated with total and anxiety sub-scores of HADS. MVBITS was also positively correlated with the RSES scores. Conclusions: The results showed that the Malay Version of Breast-Impact of Treatment Scale possesses satisfactory psychometric properties suggesting that this instrument is appropriate for assessment of body change stress among female breast cancer patients in Malaysia.

• 마이크로전자및패키징학회지
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• 제17권3호
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• pp.65-69
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• 2010

In this study, we investigated the effects of UBM(Under Bump Metallization) and solder composition on the drop impact reliability of wafer level packaging. Fan-in type WLP chips were prepared with different solder ball composition (Sn3.0Ag0.5Cu, and Sn1.0Ag0.5Cu) and UBM (Cu 10 ${\mu}m$, Cu 5 ${\mu}m$\Ni 3 ${\mu}m$). Drop test was performed up to 200 cycles with 1500G acceleration according to JESD22-B111. Cu\Ni UBM showed better drop performance than Cu UBM, which could be attributed to suppression of IMC formation by Ni diffusion barrier. SAC105 was slightly better than SAC305 in terms of MTTF. Drop failure occurred at board side for Cu UBM and chip side for Cu\Ni UBM, independent of solder composition. Corner and center chip position on the board were found to have the shortest drop lifetime due to stress waves generated from impact.

• 정신신체의학
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• 제5권1호
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• pp.97-107
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• 1997

As a preliminary step to develop the Daily stress Inventory(DSI) for assessing minor stressors frequently experienced in everyday lift. We examined the reliability and validity of the DSI. The Daily Stress Inventory(DSI), the Beck Depression Inventory(BDI), the State-Trait Anxiety Inventory(STAI), the Social Readjustment Rating Scale(SRRS) and the Minnesota Multiphasic Personality Inventory(MMPI) were administered to 111 college students. Compared with the weekly DSI Event, Impact and I/E ratio scores of the American college students, the weekly event and I/E ratio scores of the Korean college students were significantly higher but weekly Impact score was lower. The internal consistency reliability of the DSI as computed by Cronbach alpha was .98. The DSI I/E ratio scores were significantly correlated with the scores of State Anxiety$({\gamma}=.27)$ and Trait Anxiety${\gamma}=.24)$, but not with BDI scores. And the SSRS scores were not significantly correlated to the DSI Event or Impact and In ratio scores. Significant correlations were revealed between the DSI Impact scores and the Sc and Ma scales of the MMPI. And the correlation between the DSI I/E ratio scores and the L, D, Hy, Pd and Pa scales of the MMPI was also significant. But no significant correlation was found between the DSI Event scores and all the scales of the MMPI. This study suggests that the DSI can be a reliable and valid tool to assess the minor stress frequently experienced in everyday life future study should be directed to obtain normative data based on more varied and larger population. Especially gathering additional evidences for the validity of the DSI using other minor stressor scale will be required.

• 한국콘텐츠학회논문지
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• 제19권8호
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• pp.293-302
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• 2019

이 연구의 목적은 Stroke Impact Scale 3.0(SIS 3.0)의 신뢰도와 타당도를 조사하는 것이었다. 연구에서 SIS 3.0은 125명의 뇌졸중 환자를 대상으로 측정하였다(평균 = 62.7, 표준 편차 = 9.43). SIS 3.0 하위 영역들 간에 상관 분석을 통해 구성타당도를 확인하였고, MBI(Modified Barthel Index)와 K-MMSE(Mini-Mental State Examination-Korean)간의 상관을 분석하여 수렴타당도를 조사하였다. 각 항목의 특성은 고전적 문항 이론을 바탕으로 내적 합치도와 문항 변별도를 분석하였다. 이 연구를 통해 SIS 3.0의 구성타당도와 수렴타당도가 확인되었다. 감정 영역에 포함된 i 항목은 문항 변별도가 낮았지만 이 항목을 제외하고는 모두 변별도가 높았다. 하위 영역의 문항내적합치도는 0.858~0.941로 나타났다. 이 연구는 지역사회에 거주하는 뇌졸중 환자를 대상으로 임상 현장에서 SIS 3.0 사용을 위한 신뢰도와 타당도를 확인하였다는데 그 의의가 있다.