• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.73-83
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• 1994

Press formabilities of aluminum sheets for automobile body were investigated. Plane strain stretching test (called RIST-PSST), cupping test and U bending test were performed to assess the press formability of aluminum sheets respectively. The results showed that aluminum sheets are generally inferior to cold-rolled steel sheet of deep drawing quality (CSP3N) in press formability. The limiting punch height (LPH) and limiting plane strain (FLCo) of aluminum sheets are 50%-70% level compared to that of CSP3N. Moreover, the limiting drawing ratios(LDR) of aluminum sheets are ranged between 1.95 and 2.1. The poor press formability of aluminum sheets is responsible for low values of total elongation and plastic anisotropy parameter in tensile characteristic. The shape fixability of aluminum sheets evaluated in U bending test is very poor due to its low elastic modulus compared to CSP3N.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.06a
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• pp.147-162
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• 1994

Generally, the forming process of sheet metal is very complex and difficult process because of many variables such as tool geometry, material properties and lubrication. In this view point, the numerical analysis of sheet metal forming process is very difficult. High speed computer is used to model complex sheet metal forming process on a reasonable time scale. The design and development of sheet metal parts in the automotive industry and the need for improved sheet forming process and reduced part development cost have led to the use of computer simulation in tool/die design of sheet metal pressing. HMC(Hyundai Mator Company) has invested to develop programs for analysis of sheet metal forming process with connection of Universities. As a result, several programs were developed. Recently, the commercial software, PAM-STAMP of ESI was installed and is being tried to application of it to the real automotive panels. This article reviews the ongoing activities on development and application of analytical modeling of sheet metal forming at HMC.

• Proceedings of the KIEE Conference
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• summer
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• pp.67-69
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• 2004

This thesis attempts to investigate and analyze the structure of educational simulation devices implemented thus far. conducting a close analysis of their strengths and weaknesses. On this basis the author Presents and implements a new method of simulation, and continuously upgrades it for increased stability and convenience. The most important aspects of the educational simulation device described in this thesis are: first removing the editing function (scenarios. single line diagrams, and point DB), which the instructor finds time-consuming and inconvenient to use; second, developing and installing the program so as to calculate electric power flow that can measure fluctuations measurements after changing the system status; and third. implementing a Client/server mode to build a system that will make it possible to train many people at a time in remote locations. When compared to simulation devices of the Psst. the greatest differences are that algorithm-based scenarios make scenario inputs unnecessary. and that the amount of work required for the point DB and single line diagrams were minimized.

• Korean Journal of Psychosomatic Medicine
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• v.21 no.1
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• pp.44-54
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• 2013

Objectives : To investigate the frequency and clinical characteristics of premenstrual syndrome(PMS)/premenstrual dysphoric disorder(PMDD) in high school students, and determine the correlates of PMS/PMDD in association with comorbid depression and anxiety. Methods : A total of 1688 students were recruited from 5 high schools in Seoul, Korea. Subjects completed the questionnaire composed of scales to measure premenstrual symptoms, depression, and anxiety, as well as sociodemographic and reproductive variables. Subjects were categorized into 3 groups by using the Premenstrual Symptom Screening Tool(PSST) to determine the frequency and clinical characteristics of PMS/PMDD. Multivariate logistic regression was used to identify the correlates of PMS/PMDD. Results : The frequency of moderate to severe PMS and PMDD was 20.1% and 6.4%, respectively. Irritability(78.8%), fatigue(76.4%), and emotional sensitivity(69.8%) were common premenstrual symptoms, and functional impairment in academic performance(67.1%) was dominant. Dysmenorrhea[odd ratio(OR)=3.68, 95% confidence interval(CI) 2.45-5.55], family history of PMS(OR=1.91, 95% CI 1.35-2.71), and use of oral contraceptive (OR=1.85, 95% CI 1.16-2.94) were associated with the increased risk of PMS/PMDD after adjustment for depression and anxiety. Negative attitude to menses(OR=15.60, 95% CI 3.61-67.42) was associated with the increased risk of PMS/PMDD, particularly in subjects without depression and anxiety. Conclusions : PMS was common, as the frequency of PMS more than moderate severity including PMDD exceeded 25%, and disrupted daily functioning in adolescents. PMS is associated with various sociodemographic and menstrual characteristics, and these associations are affected by comorbid depression and anxiety.

• Korean Journal of Psychosomatic Medicine
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• v.23 no.1
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• pp.57-65
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• 2015

Objectives:Within the normal reproductive cycles of women, dramatic fluctuations of sexual hormones occur in the premenstrual and menopausal periods. In both periods, women are vulnerable to mood disturbances and show several somatic complaints. Based on these common clinical profiles and physiological changes, a relationship between vasomotor symptoms and the premenstrual syndrome has been suggested. However, attempts to establish such a link have yielded inconclusive results. The purpose of this study was to investigate the association between histories of premenstrual syndrome and menopausal vasomotor symptoms within different menopausal stages. Methods:This cross-sectional study recruited Korean women aged 45-64 years who were perimenopausal and postmenopausal from 16 branch offices of the Korean Association of Health Promotion. All subjects completed self-report questionnaires that asked about a history of premenstrual syndromes, vasomotor symptoms, and several other variables. Results:A total of 1054 participants(361 perimenopausal women and 693 postmenopausal women) completed the study. Severity of premenstrual symptoms significantly correlated with postmenopausal vasomotor symptoms, only in late perimenopausal(r=0.213, p=0.010) and early postmenopausal women(r=0.246, p<0.001). After adjusting for several factors related to vasomotor symptoms, a history of premenstrual syndrome was a significant predictor of moderate to very severe vasomotor symptoms in late perimenopausal(OR=5.197, p=0.005) and early postmenopausal women(OR=3.017, p=0.010). Conclusions:This study suggests that a history of premenstrual syndrome/premenstrual dysphoric disorder is differentially associated with vasomotor symptoms in the menopausal stage. Prospective studies with larger population are needed to confirm these findings