TEB (Technology Education Business) Platform development for engineering technology education

최명기,장병환,노수진,이정민,유재권 대한용접·접합학회 2020 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2020 No.11

무기력증

최명기 중앙대학교 1988 無影燈 Vol.13 No.-

파이프 서포트의 지지핀 두께와 압축하중의 상관관계 분석

최명기,박종근 한국안전학회 2022 한국안전학회지 Vol.37 No.4

Generally, in construction sites, the pipe support installation workers often use support pins of 9~10 mm which are much smaller than the safety standard sizes for work convenience. Although the safety certification standard thickness of the support pins is 11 mm, and the supervisors are often indifferent to this. Hence, products with far lower performance than the pipe support safety certification value of 40,000 N, which is applied in the supporting post-structural review, are used. Accordingly, this acts as a factor causing collapse accidents in the process of pouring concrete at the construction site. Therefore, this study performed compression experiments on new and reused pipe supports to determine how the thickness of the support pins affects the structural compression performance of the pipe support by considering the thickness of the support pins as a critical variable among various factors affecting the pipe support performance. In the course of the study, the compression test of the pipe support (V2, V4) for the new products showed that only 14 (58.3%) of the total 24 samples satisfied the safety certification standard value of 40,000 N, which indicates that more thorough quality control is required in the manufacturing process. Additionally, comparing the thickness of the support pins and their fracture shape shows that the pipes with support length of 4.0 m or longer are much more affected by the buckling of the entire length than the thickness of the support pins. Of the several factors affecting the performance of reused pipe supports, it was found that, similar to the new products, the use of support pins, with thickness of 12 mm rather than 11 mm, can satisfy the safety certification value more appropriately. Therefore, regardless of the state of usage, it could be concluded that it is necessary to use 12 mm products, whose thickness is larger than that of the safety certification standard value of 11 mm, to improve the performance of the pipe supports.

N₂분위기에서 Solder 접합부의 젖음성 및 결함특성에 관한 연구

최명기,황선효,이창배,정재필,서창제 大田産業大學校 2001 한밭대학교 논문집 Vol.18 No.-

본 실험을 통하여 대기와 N_2분위기에서의 젖음력과 솔더 접합부의 결함특성에 대하여 연구 검토하였다. 모든 시편 조건에서 질소분위기에서의 젖음성이 대기 중에서 젖음성 보다 좋아졌다. 또한 N_2유량이 증가함으로서 젖음 시간은 짧아지고, 젖음력은 증가하였다. N_2분위기에서 브리지(Bridge)발생률이 25∼76%정도로 현저히 감소하였다. N_2분위기에서는 젖음력의 향상으로 솔더 접합부가 안정되었으며 결함 발생률도 현저하게 감소되는 것을 확인할 수 있었다. This study was prepared to find out wettability and properties of defects on solder joints in N_2 conditions. The wettability of solder joints in N_2 condition was better than that in atmosphere condition, and when the flow rate of N_2 was increased, it is found that the wetting time got a little bit short and the wetting force got stronger as time passed. Also the rate of bridge defects was specially decreased in N_2 conditions, showing the decreasing ratio of 25∼76%. The solder joints were stabilized and the rate of defects was decreased by cause to increasement of wetting force in N_2 conditions.

지하철 건설현장 재해 분석 및 재해손실비용 추정에 관한 연구

최명기 한국기술사회 2001 技術士 Vol.34 No.5

The industrial accident in subway of late is increasingly coming to the front as a serious problem of society because a scale of industrial accident is a large size, and powerfulness, while the percent of accident is decreasing as a result of industrial facilities with the largeness of equipment, automation, and high horse-powering. In this paper, a study on the estimation of accident loss prevention cost and risk analysis in subway construction is proposed as an alternative to the techniques currently used in the general construction projects safety. Then the concept of risk evaluation using a risk assessment model is presented to drive value of risk and numerical example for risk analysis. A means for this does grasp the importance of educational factor by way of analyzing the causes of accident through statistical data of labor department, emphasizing the necessity and the importance of safety education, being helpful to act safety by decreasing insecure activity which ranks the majority of accident causes with putting the education program, form, method into practice that are suitable for a place of business.

다함께 죽는건 죽는게 아니다

최명기 중앙대학교 1987 無影燈 Vol.12 No.1

저잔사 플럭스를 사용한 플로우 솔더링부의 젖음성 및 결함거동에 관한 연구

최명기,이창열,정재필,서창제,신영의 대한용접접합학회 1998 대한용접·접합학회지 Vol.16 No.6

Effects of non-cleaning and cleaning fluxes on the wetting properties and defects at flow soldered joints were investigated. Non-cleaning flux (R-type of 3.3% solid content) and cleaning flux (RMA-type of 15% solid content) were used. Wetting test was accomplished by wetting balance method with changing surface state of wetting specimen, CU. Sn-37%Pb solder was used for wetting test and flow soldering. As experimental results, the wetting time for vertical force from the surface tension being zero was mainly affected by surface state of the wetting specimen. Non-cleaning flux had a good wettability compared with cleaning flux. In case of non-cleaning flux, conveyor speed had a great affection to defects of bridge, icicle, and poor solder.

진달래와 무궁화

최명기 중앙대학교 1990 無影燈 Vol.15 No.-

[건설업체 대안] 중대재해처벌법 대응을 위한 중소규모 건설회사의 전략과 방향

최명기,Choe, Myeong-Gi 한국건설관리학회 2022 건설관리 : 한국건설관리학회 학회지 Vol.23 No.2

질소 분위기에서 저잔사 플럭스를 사용한 마이크로 솔더링에 관한 연구

최명기,정재필,이창배,서창제,황선효 한국마이크로전자및패키징학회 2000 마이크로전자 및 패키징학회지 Vol.7 No.4

질소분위기 중에서 솔더 접합부의 특성 및 solderability을 검토하기 위하여 대기분위기와 질소분위기에서의 젖음성을 평가하였다. 또한 솔더접합부의 브리지결함(bridge defect)을 대기와 질소분위기 중에서 비교 검토하였다. 이 결과, 질소분위기 중에서 Cu표면을 사포로 연마한 시편, Cu표면에 Sn-Pb 및 Sn으로 도금한 시편에서 젖음성이 향상되었다. 대기분위기에 비해 젖음시간은 약 0.2~0.45초 정도 시간이 감소하였고, 최대젖음력 ($F_{max}$)도 대기중에 비해 약 1.8~2.8 N 정도가 커졌다. 질소유량에 따른 젖음시간($t_2$)과 젖음력을 측정한 견과 질소유량이 10 1/min에서 30 1/min으로 증가함에 따라 대기중 분위기에 비해 젖음시간($t_2$)는 약 0.25초 정토 감소하였고, 젖음력은 2.3 N 정도 상승하였다. 따라서, 질소분위 기에서 무세정용 플럭스를 사용해도 젖음성이 떨어지는 것을 보완 할 수 있다. 질소분위기에서는 젖음성을 향상시키고 산화물(dross)를 억제시켜주어 대기 중 보다 브리지 (Bridge)발생률이 25~76%정도 떨어졌다. 브리지 발생률은 피치간격이 미세할수록 질소분위기가 대기 중 보다 감소하였다. The purpose of this work is to evaluate the solderahility and characteristics of solder joints. Bridge defect of solder joint was examined in natural atmosphere and $N_2$ condition. Consequently, wettability was excellent for each of Sn-Pb plated Cu specimen, Sn plated Cu specimen, and Cu polished in $N_2$ condition. The wetting time in $N_2$ condition was shorter than that of natural atmosphere condition, showing the decreasing values of about 0.2~0.45 seconds. The max. wetting force under the $N_2$ condition was more increasing that of natural atmosphere condition, showing the increasing values of about 1.8~2.8 N. With the result of wetting balance test, the wetting time ($t_2$) and wetting farce according to increasing amount of $N_2$ from 10 1/min to 30 1/min, the wetting time ($t_2$) was reduced about 0.25 second and wetting force was increased about 2.3 N. In non-cleaning flux, when $N_2$ gas is applied, it is compensated to decrease of wettability. In the case of using the $N_2$ gas, the wettability was improved. The reason for improving wettability is due to preventing the formation of dross. The generation rate of bridge in $N_2$ condition decreased than that of natural atmosphere, and when the specimen had a fine pitch, the rate of bridge defects was considerably decreased in $N_2$ condition, showing the decreasing rate of 25~75%.