• 국방과기술
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• 4호통권122호
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• pp.38-45
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• 1989

Mig-29는 1980년대의 비행능력과 1970년대 전반의 무장시스템 능력을 결합한 전투기로 보여지고 있다. 부대배치는 1983년부터 시작되었다고 하며, 소련의 신형 전투기 트리오중 가장 기수가 많을 것으로 추정된다. 소련권 여러나라에 제공되고 있는 것으로 전해지고 있으며, 인도가 1백기이상의 면허생산계약을 체결하였다는 사실은 주목할만 하다. 시리아에 약 20기가 공여되었고, 이라크와 유고에도 인도가 이루어졌음이 확인되었다. 극동에서는 서울올림픽의 개막에 앞서 북한에 12기가 공여되었다는 정보가 있다

• 한국산학기술학회논문지
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• 제18권11호
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• pp.124-129
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• 2017

본 연구에서는 철도차량의 경량 차체 소재로 주로 사용되는 알루미늄 합금 (Al-6005-T6) 압출재에 대한 마찰교반접합 적용 연구를 수행하였다. 용접속도를 300 mm/min으로 고정시킨 채 회전 공구의 회전속도를 600, 900, 1200, 1600 rpm으로 변화시킬 때 미세구조 및 기계적 특성의 변화에 대해 평가하였다. 특히, 동일 소재에 대해 전통적인 용접방법인 MIG 용접된 시편과의 비교를 통해 마찰교반접합법의 철도차량 적용성에 대해 논하였다. MIG 용접방법과는 달리, 마찰교반접합부에는 미세기공이 발견되지 않았으며, 경도 측정 결과 공구의 회전속도가 빨라질수록 높아진 입열량에 따라 heat affected zone (HAZ)의 범위가 넓어지고 결정립 조대화에 따라 HAZ의 경도 또한 낮아지는 것을 확인하였다. 인장시험 결과 HAZ지역에서 파단이 발생하였으며, 본 연구에서 설정한 공구의 회전속도 범위에서는 nugget 부의 경도 변화는 발견되지 않았으나 rpm이 올라갈수록 인장강도와 항복강도가 떨어지는 경향을 보였으며 이는 경도 시험에서와 같이 HAZ지역의 결정립 크기의 증가로 인한 현상으로 판단된다.

• Journal of Welding and Joining
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• 제29권1호
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• pp.80-84
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• 2011

The weight reduction of the transportations has become an important technical subject Al and Al alloys, especially Al 5052 alloys have been being applied as door materials for automobile. One of the most widely known car weight-reduction methods is to use light and corrosion-resistant aluminum alloys. However, because of high electrical and thermal conductivity and a low melting point, it is difficult to obtain good weld quality when working with the aluminum alloys. Also, Pulse MIG welding is the typical aluminum welding process, but it is difficult to apply to the thin plate, because of melt-through and humping-bead. In order to enhance weld quality, welding parameters should be considered in optimizing the welding process. In this experiment, Al 5052 sheets were used as specimens, and these materials were welded by adopting new Cold Metal Transfer (CMT) pulse process. The proper welding conditions such as welding current, welding speed, torch angle $50^{\circ}$ and gap 0~1mm are determined by tensile test and bead shape. Through this study, range of welding current are confirmed from 100A to 120A. And, the range of welding speed is confirmed from 1.2m/min to 1.5m/min.

• Journal of Trauma and Injury
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• 제35권4호
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• pp.248-254
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• 2022

Purpose: To analyze the data of trauma patients with undetected injuries at the time of initial resuscitation during the primary and secondary surveys. Methods: We retrospectively reviewed the medical records of 807 patients who were hospitalized at the National Trauma Center, Seoul, Korea from June 1, 2019 to June 30, 2021. Results: In trauma patients with an Injury Severity Score ≥16 accounted for 27.5% in the non-missed injury group (non-MIG), but this rate was considerably higher at 71.2% in MIG. The mean hospitalization longer in MIG (50.90±39.56) than in non-MIG (24.74±26.11). The proportion of patients with missed injuries detected through tertiary trauma survey (TTS) was 28 patients (23.5%) within 24 hours, 90 patients (75.6%) after 24 hours to before discharge. The majority of missed injuries were fractures (82.4%) and ligament tears (8.4%), which required consultation with the orthopedic department. The final diagnoses of missed injuries were confirmed by computed tomography (44.5%), magnetic resonance imaging (19.3%), X-ray (19.3%), bone scan (11.8%), and physical examination (5.0%). Conclusions: TTS is considered a useful process for detecting missed injuries that were not identified at the time of initial resuscitation in the primary and secondary surveys. In the future, to detect missed injuries quickly, it is necessary to develop a suitable TTS program for each trauma center. In addition, further research is needed to verify the effectiveness of the protocolized TTS and survey chart to improve the effectiveness of TTS.

• Journal of Welding and Joining
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• 제15권4호
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• pp.166-177
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• 1997

The high strength AlZnMgCu0.5 alloy is a light metal with good age hardenability, and has a high tensile and yielding strength. Therefore, it can be used for structures requiring high speciple strength. Even though high strength AlZnMgCu alloy has good mechanical properties, it has a lot of problems in TIG and MIG welding processes. Since lots of high heat absorption is introduced into the weldment during TIG and MIG processes, the microstructural variation and hot cracks take place in heat affected zone. Therefore, the mechanical properties of high strength AlZnMgCu0.5 alloy can be degraded in weldment and heat affected zone. Welding process utilizing high density heat source such as electron beam should be developed to reduce pore and hot cracking, whichare usually accompanied by MIG and TIG welding processes. In this work, electron beam welding process were used with or without AlMg4.5Mn as filler material to avoid the degradation of mechanical properties. Mechanical and metallurgical characteristics were also studied in electron beam weldment and heat affected zone. Moreover hot cracking mechanism was also investigated.

• 한국기계가공학회지
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• 제15권1호
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• pp.110-115
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• 2016

The need for high-strength galvanized steel has recently increased because of the increased number of car consumers who want improved efficiency and exterior quality. High-strength galvanized steel with high corrosion resistance improves the durability of products and exterior quality. Furthermore, the gilt of zinc does not come off during machining because of the fine adhesive property of zinc. When these are welded, zinc has a lower melting temperature than iron, so zinc is more quickly vaporized than iron. Vaporized zinc can stick to electrodes, which increases spatter in welding transportation. Created spatter can enter the molten pool and develop into inner defects or blowholes and pits. Scattered spatter sticks to the product, which leads to the secondary cost of spatter removal. Therefore, in this study, comparisons of amounts of spatter generated are conducted according to the composition of shielding gas in the MIG and CMT processes to find optimal welding parameters.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.216-218
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• 2006

The application of aluminium alloy is increasing for lightweight and high quality transport vehicle. In this study, therefore, it is intended to apply the high speed hybrid welding method for marine grade aluminium alloy(A5083) used for shipbuilding that consists of 3 kW CW Nd:YAG laser and MIG welding process. For this purpose, the characteristics of process parameters(laser & arc combine angle and focal position of hybrid head to specimen) are investigated for hybrid fillet joint. This study also describes determination of heat distribution using finite element model of the T-joint fillet weld using the in-house solver which has been validated for different type of welding problems.

• 보건교육건강증진학회지
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• 제31권4호
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• pp.37-49
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• 2014

Objectives: The aim of this study was to evaluate the effects of a lifestyle modification program for Korean adults with cardiovascular disease risk factors on their health behaviors and health status. Methods: A total of 448 adults with abdominal obesity and additional cardiovascular disease risk factors(high blood pressure, low HDL-cholesterol, high triglyceride or high blood glucose) were randomly assigned to either an intensive intervention group (IIG, n=216) or a minimal intervention group(MIG, n=232). Participants in the IIG received lifestyle modification program which consisted of health counseling with nutrition assessment, health booklet and health diary, while those in MIG received minimal information. Results: The participants in the IIG significantly improved dietary habits(p<.05), retrained eating(p<.001), external eating(p<.01) behaviors, leisure time physical activity(p<.05), dietary self-efficacy(p<.01), exercise self-efficacy(p<.01) and MetS score(p<.001) after 3 months. In addition, the participants in the IIG showed more improvement in dietary habits(p<.05) compared with those in the MIG. Conclusion: The lifestyle modification program was effective in improving some health behaviors, behavioral determinants and cardiovascular risk factors for a short term.

• Journal of Welding and Joining
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• 제14권4호
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• pp.53-61
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• 1996

It was attempted to improve the wear resistance of Al alloy under the load condition by making a formation of the thicker surface hardening alloy layers. The thicker surface hardening alloy layers were formed on 6061 Al alloys overlayed by MIG and TIG welding process with Cu powders feeding. The characteristics of hardening and wear resistance have been investigated in relation to the microstructures of alloyed layers, with a selection of optimum alloying conditions for formation of overlaying layer. The results obtained were summarized as follows With increasing feeding rate of Cu powders by MIG welding, the hardness and specific wear of the overlay weld alloys were increased. It is considered that these high hardness and specific wear of overlay weld alloys were due to the formation of Θ($Al_2Cu$) phases. With increasing feeding rate of Cu powders by TIG welding, the hardness and specific wear of the overlay weld alloys were increased in feeding rates 12 and 18g/min. However, the hardness and specific wear were decreased in the powder feeding rate 38g/min. It is considered that considered that decrease of hardness and specific wear in the powder feeding rate 38g/min due to formation of ${\gamma}$($Al_4Cu_9$) phases.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.331-333
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• 2005

It comes up conversation in automobile industry that some technologies related to production and quality for goods have to be developed to make rationalization of the unit cost of production because material of car muffler is replaced by expensive stainless steel having corrosion-resistance and oxidation-resistance. Quality evaluation and control is direct method for the company producing welded goods in large quantities to increase productivity and to improve quality. It seems that prevention of inferior quality and increasement of productivity will be hard if production design does not have quality evaluation method related to weld assembly, They have been producing welded goods using MIG weld but still do not have not only quality evaluation method but also evaluation criterion for welded joint. In this study, the way for development of quality evaluation method is showed by analysis and calculation of waveform to improve technology related to welding process