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RISS 인기검색어
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- 저자 : 최동필 (검색결과 66 건)
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3차원 납 접합부 형상을 이용한 표면실장기술의 적정 납량 결정
최동필,김성관,유중돈 대한용접접합학회 1996 대한용접·접합학회지 Vol.14 No.2
In order to rpovide proper SMT design criteria in a systematic way, a mathematical formulation has been developed to predict the configuration of the solder fillet formed between the gullwing type lead and rectangular pad. Effects of SMT design parameters such as the solder volume and pad dimension on the solder profile are investigated using the FEM that calculates the 3D configuration by minimizing the energy due to surface tension and gravity in the equilibrium state. Design criteria of QFP and SOP are illustrated by plotting the acceptable range of the solder volume with respect to the length and width ratios of the pad and lead. The results show that the acceptable design range increases with increase in the pad length and width. The pad length has more significant effects on design criteria compared with the pad width, and Bond number can be utilized to predict the joint quality.
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워킹이 Gullwing 리드의 솔더 접합부 형상에 미치는 영향
최동필,유중돈,이태수,최상균 대한용접접합학회 1998 대한용접·접합학회지 Vol.16 No.4
During the reflow process in SMT, the molten solder has been observed to move upward and solidify along the gullwing lead, which is called the wicking phenomenon. In this paper, possible causes of the wicking are investigated, and its effects on the solder joint profile are quantitatively estimated by introducing the wicking constant. The free energy reduction by intermetallic formation between the copper and tin seems to be the major source of wicking action. The joint profiles of the gullwing lead are calculated using the previous finite element formulation incorporated with the wicking constant. The calculated results show reasonably good agreements with the experimental data when the wicking effects are considered.
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최동필,이주영,안성복,김현창 대한고혈압학회 2012 Clinical Hypertension Vol.18 No.1
Background:Wide pulse pressure associates with atherosclerosis, but it is unclear whether pulse pressure within a relatively normal range is associated with atherosclerosis in younger populations. The aim of this study was to investigate the association between pulse pressure and the carotid intima-media thickness (IMT) in healthy adolescents. Methods: Study participants included 250 (129 males and 121 females) adolescents who were 17 to 19 years old and in the third grade of a high school in Jangseong, Korea between November 20 and December 1, 2009. Pulse pressure was determined as the difference between systolic blood pressure and diastolic blood pressure which were measured with an oscillometric sphygmomanometer. IMT values were ultrasonographically measured at right and left common carotid arteries, and average of the mean IMT at each artery was used for analysis. Results: There was a significant correlation between pulse pressure and carotid IMT before (Pearson coefficient r = 0.2037, p = 0.001) and after (r = 0.1479, p = 0.020) adjustment for sex. When adjusted for sex, age, waist circumference,fasting blood glucose, and total/high-density lipoprotein cholesterol ratio, 10 mm Hg increase in pulse pressure was associated with increase of IMT in total (β = 10.9 ㎛, p = 0.003), in males (β = 17.3 ㎛, p < 0.001), but not in females (β = 3.609 ㎛, p =0.518). Conclusions: This study suggests that higher pulse pressure may be associated with increased carotid IMT even in healthy male adolescents.
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유한요소 모델링을 이용한 Gullwing 리드의 3차원 솔더 접합부 형상 예측
최동필,유증돈,이태수 대한용접접합학회 1998 대한용접·접합학회지 Vol.16 No.4
The three-dimensional profile of a solder fillet is predicted by minimizing the surface tension and gravity energies of the solder joint using finite element modeling. Geometric complexity stemming from the inclined plane of the gullwing lead is resolved by employing three element types. These element types are used to describe the joint profile formed on the vertical, inclined and interfacial planes. The predicted solder joint profiles show good agreements with the experimental data provided that the solder volume is adjusted considering the wicking effects. Effects of the pad length, inclined lead angle and solder volume on joint profiles are also investigated.
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한국 농업인의 쯔쯔가무시증 발생률: 농업인안전보험자료를 이용하여
최동필,김경수,이민지 한국보건정보통계학회 2022 보건정보통계학회지 Vol.47 No.4
Objectives: We investigated the incidence rate of Scrub typhus in farmers. Methods: Data were obtained from 2016 to 2021 in the farmers’ safety insur- ance from NongHyup Life Insurance. The incidence was defined as a newly diagnosed patients with Scrub typhus in 2016-2020. The incidence rate was confirmed by sex, age and administrative districts. Results: The age-standardized incidence rate of Scrub typhus was 115 per 100,000 people from 2016 to 2020. The crude rate was presented to be 8.9, 43.8, 79.9, 127.2, 156.3, and 174.3 per 100,000 people, respectively, in the 40s to 80s or over. According to administrative districts, the highest crude rate was 201.6 and 193.0 per 100,000 people in Jeonnam and Gyeongnam, respectively, and the lowest crude rate was 6.0 per 100,000 people in Gangwon. And the monthly incidence was 54.3% in November and 32.0% in October, concentrated in autumn. Conclusions: The age-standardized incidence rate of Scrub typhus in Korea was 115.1 per 100,000 people, and it occurred more frequently in the south- ern regions in terms of administrative districts and increased with age. Based on this, it is thought that it will be helpful in establishing a management plan to prevent Scrub typhus. .
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