• 한국안전학회지
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• 제25권3호
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• pp.34-39
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• 2010

Unidirectional Carbon Fiber Reinforced Plastics (CFRP) are advanced materials which combine the characteristics of the light weight, high stiffness and strength. For those reasons, the use of the unidirectional CFRP has increased in jet fighters, aerospace structures. However, unidirectional CFRP composites have a lot of problems, especially delamination, compared with traditional materials such as steels and aluminums, and so forth. Therefore, the interlaminar fracture toughness for a laminate CFRP composite is very important. In this study, The mode II interlaminar fracture toughness was measured by using center notched flexure(CNF) test specimen. The CNF specimens using unidirectional carbon prepreg were fabricated by a hot-press with the gage pressure and temperature controller. And three kinds of a/L ratio was applied to these specimens. Here, we discuss the relations of the crack growth and the mode II interlaminar fracture under the four point bending CNF test. From the results, we shows that mode II interlaminar was occurred when the more $a_0$/L ratio, the less load. And $G_{IIC}$ also were obtained as 5.33, 2.9 and $0.58kJ/m^2$ according to $a_0$/L ratio=0.2, 0.3 and 0.4.

• Tribology and Lubricants
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• 제33권2호
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• pp.45-51
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• 2017

Engine oil is a substance used for the lubrication of internal combustion systems. However, in some case, defects in engine systems may contaminate engine oil with fuel. Contaminated engine oil can cause problems in the normal functioning of a vehicle. In this study, we investigate the functional properties of engine oil contaminated with diesel fuel. The test results indicate that the engine oil contaminated with diesel fuel has low flash point, pour point, density, kinematic viscosity and cold cranking simulator value. The contaminated engine oil which has low plash point can cause fire and explosion accident. Furthermore, a four ball test indicates that the contaminated engine oil increases wear scar to poor lubricity. Moreover, we investigate the GC pattern using SIMDIST (simulated distillation) for determination of diesel in engine oil. The SIMDIST analytic result, diesel was detected at earlier retention time than engine oil in chromatogram. Thus the SIMDIST method can define whether engine oil is contaminated by diesel fuel or not. We can use the SIMDIST method for the diagnosis of oil condition instead of analyzing other physical properties that require many analytic instruments, large volume of oil sample and long analysis time.

• Journal of Mechanical Science and Technology
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• 제17권8호
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• pp.1148-1155
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• 2003

The finite element method is one of the methods widely applied for predicting vibration in mechanical structures. In this paper, the effect of the mesh size of the finite element model on the accuracy of the numerical solutions of the structural vibration problems is investigated with particular focus on obtaining the optimal mesh size with respect to the solution accuracy and computational cost. The vibration response parameters of the natural frequency, modal density, and driving point mobility are discussed. For accurate driving point mobility calculation, the decay method is employed to experimentally determine the internal damping. A uniform plate simply supported at four corners is examined in detail, in which the response parameters are calculated by constructing finite element models with different mesh sizes. The accuracy of the finite element solutions of these parameters is evaluated by comparing with the analytical results as well as estimations based on the statistical energy analysis, or if not available, by testing the numerical convergence. As the mesh size becomes smaller than one quarter of the wavelength of the highest frequency of interest, the solution accuracy improvement is found to be negligible, while the computational cost rapidly increases. For mechanical structures, the finite element analysis with the mesh size of the order of quarter wavelength, combined with the use of the decay method for obtaining internal damping, is found to provide satisfactory predictions for vibration responses.

• 대한기계학회논문집
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• 제17권11호
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• pp.2752-2761
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• 1993

The purpose of this study is to confirm the decreasing problems of residual bending strength, and the fracture machanism experimentally when CFRP composite laminates are subjected to Foreign Object Damage. Composite laminates used for this experiment are CFRP orthotropy laminated plates, which have two-interfaces [O/sub 6//sup o//90/sub 6//sup o/]sub sym/ and four-interfaces [O/sub 3//sup o//90/sub 6//sup o//O/sub 3//sup o]/sub sym/. When the specimen is subjected to transverse impact by a steel ball, the delamination area generated by impact damage is observed by using SAM(Scanning Acoustic Microscope). also, Thefracture surfaces obtained by three-point bending test were observed by using SEM (Scanning Electron Microscope). Then, fracture mechanism was investigated based on the observed delamination area and fracture surface. The results were summarized as follows; (1) It is found that for the specimen with more interface, the critical delamination energy is increased while delamination-development energy is decreased. (2) Residual bending strength of specimen A is greater than that of Specimen B within the impact range of impact energy 1. 65J (impacted-side compression) and 1. 45J (impacted-side tension). On the other hand, when the impact energy is beyond the above ranges, residual bending strength of specimen A is smaller than that of specimen B. (3) In specimen A and B, residual strength of CFRP plates subjected to impact damage is lower in the impacted-side compression than in the impacted-side tension. (4) In the case of impacted-side compression, fracture is propagated from the transverse crack generat-ed near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension.

• Journal of Preventive Medicine and Public Health
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• 제32권1호
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• pp.95-100
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• 1999

Objectives. This study surveyed medical students attending clerkship to assess their attitude toward and knowledge about breastfeeding, and self-confidence to manage common breastfeeding problems. Methods. A self-report questionnaire was administered to the 323 medical students at four medical colleges in Taegu in May 1997. The response rate was 92.9%, but the respondents used in the final data analysis were 245 (75.8%) due to missing variables. Results. Overall, respondents showed equivocal attitudes toward breastfeeding (mean score 2.9 on a 6-point scale). Knowledge about breastfeeding was substantially low with the median % correct 39.2%. Of nine knowledge areas, weak areas were especially 'contraindications and barriers to breastfeeding', 'use of breastfeeding aids', 'expression and storage of breast milk'. Those reported to be confident to manage common breastfeeding problems were only 25.7%. Correlations between knowledge and self-confidence were not statistically significant except in college A (r=0.35, p<0.05). Correlations between knowledge and attitude were not significant. Conclusions. These results suggest that medical students attending clerkship in Taegu show equivocal attitudes toward breastfeeding, low self-confidence to manage common breastfeeding problems and have substantially limited level of knowledge. There should be more concerted efforts to improve this situation on the part of those involved in breastfeeding education.

• 무역상무연구
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• 제51권
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• pp.3-54
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• 2011

The important and main purpose of revision of Incoterms rules are to adapt it to contemporary commercial practice in world trade, and to contribute to great service to foreign trade. Incoterms$^{(R)}$ 2010 revision basically focuses on trade terms to be used for any mode or modes of transport at compared Incoterms 2000 gouping in four basically different categories, and presents trade terms to be used for traditionally seaborn trade. Therefore the former is for trading in manufactured goods involved in containerization, the latter is for trading in community. This study focuses on a motive of revisions and main features of the Incoterms$^{(R)}$ 2010 rules, an outline, the problems and alternative of them. In conclusion, I would like present as follows; (1) Although they only concerned the models of delivery and critical point, they only say a few of the many factors of a sale contract, that is to say for the devision of fuctions, costs and risks between the contracting parties as supplement law, but the guestion of the legal position of Incoterms rules is various in different countries and scholars. in spite of that, it must focus on the practical application and the wide acceptance of Incoterms rules in world trade. (2) Although they present more simple and clear, unfricative, than Incoterms 2000 rules, in order to help users, the need to unify consistently and fully explanate in contents and expression. (3) Introduction and guidance note of Incoterms$^{(R)}$ 2010 rules basically focuses on the understanding of a motive of revisions as compared Incoterms 2000 rules. But it is well advised to do this on the assumption of understanding the various basic meaning of terms. (4) finally, trade concerned regulations take account of the reflection for the application to domestic and international trade according to formally reconization of availability for both trade.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.205-212
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• 2018

본 연구에서는 상용 해석프로그램에서 구현하기에 어려움이 있는 지반공학적 문제를 해결하기 위한 쉽고 직관적인 해석 프로그램 개발의 일환으로 계산의 정확도가 상대적으로 높은 요소를 채택한 유한요소법을 정식화 하고 해석과정을 프로그램화 하였다. 개발된 프로그램의 계산과정에 있어서의 신뢰성 확인을 위해 두 가지 예에 대한 해석을 수행하고 결과분석을 해 보았는데 첫 번째 예는 등방구속압이 요소에 작용하는 경우이고 나머지 예는 전단응력이 요소의 측면에 작용하는 경우이다. 유한요소를 구성하는 요소로는 등매개변수 사변형 요소를 채택하였는데 요소내의 변위는 요소의 절점변위와 형상함수로 표현된다. 전체좌표(global coordinate)에 의한 미분계수로 표현되는 변형률을 얻기 위해 자코비언과 자연좌표(natural coordinate)를 이용하는 계산과정을 코딩하였다. 요소의 강성행렬을 정의하는 이중적분식을 수치적분으로 변환시키기 위해 4점 가우스 구적법을 적용하였다. 개발된 프로그램의 계산과정 검증을 위해 등방구속압이 작용하는 요소에 대한 해석을 수행한 결과 요소내의 네 개의 가우스점과 요소 중앙에 대해 계산된 응력값이 등방구속압과 일치됨을 알 수 있었다. 개발된 프로그램의 계산과정 검증을 위해 전단응력이 작용하는 요소에 대한 해석을 수행한 결과 요소내에 발생되는 횡방향응력 및 연직응력이 위치에 따라 변화됨을 알 수 있었으며 외력에 대한 발생응력의 크기 및 분포양상이 합리적임을 알 수 있었다.

• 여성건강간호학회지
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• 제7권1호
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• pp.30-43
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• 2001

This was a pre-experimental study to confirm the breast-feeding ability and effect of follow up care on the breast-feeding rate and the breast-feeding method by the mother-infant breast-feeding assessment tool for the mothers who got the breast-feeding education. The subjects were 46 mothers who experienced normal delivery of infants at a college hospital in K-city, Kyungsangbuk-do, from July 1 to October 21, 2000. The instrument for data obtainment were The Mother-Infant Breast-Feeding Assessment Tool of Johnson et al. (1999), and The Breast- Feeding Method Measurement Tool of Jeong, Geum-hee(1997). This instrument was reliable, showing Cronbach $\alpha$.751. This study classified them into 3 groups: at high risk for breast-feeding failure, at risk for breast-feeding problems, and at low risk for breast-feeding failure by the mother-infant breast-feeding assessment tool on the day of discharge from the hospital after delivering individual breast-feeding education to the subjects. This study investigated the breast-feeding rate and the breast-feeding method through mail questionnaire at the four week after childbirth, and through the phone counselling and the home visit for follow up care at the first week and the second week after childbirth. The sixth week after childbirth, this study investigated the breast-feeding rate by phone. The data analyzed the hypothesizes by $x^2$-test, paired t-test, ANOVA, Wilcoxon signed rank test, Wilcoxon rank sum test and trend analysis using SPSS/PC+ WIN 10.0 program. The results were as follows : 1) Hypothesis 1-1, "there won't be any difference the breast-feeding rate of a group at risk for breast-feeding failure by the time elapsed" was supported through constant the breast-feeding rate, because changes in the breast-feeding rate by the time elapsed after childbirth wasn't statistically significant(t= -1.501, p=.270). Hypothesis 1-2, "there won't be any difference the breast-feeding rate of group at low risk for breast-feeding failure by the time elapsed" was supported through constant the breast-feeding rate, because changes in the breast-feeding rate by the time elapsed after childbirth wasn't statistically significant(t=-1.732, p=.225). 2) Hypothesis 2-1, "there won't be any difference between the breast-feeding method of group at risk for breast-feeding failure for four weeks after childbirth and just after childbirth” was rejected, because the mean point of post test appeared to be higher than that of pre test(t=-7.267, p=.000). Hypothesis 2-2, "there won't be any difference between the breast-feeding method of the group at low risk for breast-feeding failure for four weeks after childbirth and just after childbirth" was rejected, because the mean point of post test appeared to be higher than that of pre test(t=-2.501, p=.012). 3)The 3rd hypothesis, "there won't be any difference between breast-feeding method of groups at risk for breast-feeding problems and at low risk for breast-feeding failure at the 4th week after childbirth and just after childbirth" didn't show any difference between the breast-feeding method of groups at risk for breast-feeding problems and at low risk for breast-feeding failure in the advance test(t=-1.521, p=.130) but there was difference between them in post test (t=-2.012, p=.044). As a result, the 3rd hypothesis was supported by pre test, but it was rejected by post test. In conclusion, this study confirmed breast- feeding education and follow up care just after childbirth were effective for the breast-feeding rate and method. Accordingly, it is proposed that successful nursing intervention of breast-feeding to be necessary by continuously providing follow up care through the mother-infant breast-feeding assessment tool as well as to execute individual breast-feeding education to mothers just after childbirth.

• 한국주거학회논문집
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• 제19권4호
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• pp.79-87
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• 2008

Snoezelen, multi-sensory stimulation, provides stimulation through the visual, aural, tactile, olfactory, gustatory and proprioceptive senses. Its aim is to be a relaxing, feeling of safety, novelty and stimulation with no expectations for performance. Agitated behavior of people with dementia causes significant problems and distress for cares. The objective of this research study was to test the effects of Snoezelen room on physical and verbal agitated behaviors of people with dementia. Four patients participated five sessions in Snoezelen room of 'F' dementia care facility in Sweden. Assessment instrument was basically used Cohen-Mansfield Agitation Inventory-Short Form to be rated by caregivers on a 5-point frequency scale. Pre-trial and post-trial assessments were carried out during $27^{th}$ Aug.-$27^{th}$ Sept. 2007. Result shows that Snoezelen room has some short-term positive effect on agitated behavior even though there was a considerable variation individuals responded. This result adds to the increasing evidence that Snoezelen could be a therapeutic environment for the elderly with dementia. Further research study, with larger number of participation, and a control group is required to establish more scientific evidence of Snoezelen effects on health outcome.

• 대한간호학회지
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• 제30권4호
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• pp.1078-1087
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• 2000

The purpose of this study was to develop and to evaluate the Computerized Nursing Diagnosis/ Intervention System for Nutritional and Eliminative Problems for clinical application. Each stage was processed based on the System Development Life Cycle. At the Strategy Planning Stage, valid nursing diagnoses and interventions were chosen. At the System Analysis Stage, a nursing diagnosis and intervention flowchart was drawn up. At the System Design Stage, a system was developed based on the flowchart and named the Nursing Diagnosis/Intervention System. The Nursing Diagnosis/Intervention System consisted of the Patient's Basic Information, Patient's Nursing Process, Nursing Process, and Code Registration. Each element in flowchart was coded and made into a database. The System was used and evaluated. A total of 30 cases were collected. After the application, the nurses evaluated the System using a 5 point Likert scale. Every item was scored at three points or more and 13 out of 17 items were scored at four points or more, thus the Nursing Diagnosis/Intervention System that was developed in this study was regarded as a useful one.