연료전지로 구동되는 TIG-용접기용 DC-DC 컨버터 개발

민명식(Myung-Sik Min),박상훈(Sang-Hoon Park),전범수(Byum-Soo Jeon),원충연(Chung-Yun Won) 한국조명·전기설비학회 2009 조명·전기설비학회논문지 Vol.23 No.8

본 논문은 연료전지스택을 입력전원으로 하는 TIG-용접기용 전력변환장치를 제안하였다. 일반적으로 TIG-용접기의 전원공급장치는 상용전원을 이용한 다이오드 브리지 정류회로를 사용한다. 이런 회로의 경우 다이오드 정류기와 용량이 큰 캐패시터를 사용하게 되므로 부피가 커지고, 입력전류는 맥동성분과 고조파를 포함하게 된다. 또한, TIG-용접기는 상용전원의 사용이 여의치 않은 도서산간지역이나 특수한 환경에서는 소형 경량의 이동성이 수월한 전원장치 및 전력원을 필요로 하게 된다. 따라서 본 논문의 TIG-용접기용 전력변환장치는 고체고분자형연료전지(PEMFC)를 입력전원으로 사용하고, 부스트 컨버터의 기능과 인버터 용접전원의 기능을 하나의 풀-브리지 컨버터로 구성하였다. 제안한 연료전지를 이용한 TIG-용접기용 전력변환장치는 컴퓨터 시뮬레이션과 실험을 통하여 성능을 검증하였다. This paper presents the power conversion system for TIG-welder using the fuel cell stack. Generally, power supply for TIG-welder uses the front-ended diode bridge rectifier by common AC power source. In this case, power supply of TIG-welder increases in volume because of using bulky capacitor and diode-rectifier. Also, input current includes ripple and harmonics. Moreover, TIG-welder will be demand the power supply with lightweight and easy movement in the areas like as the islands and mountainous areas or the special environment are not use common AC power source. Thus, input power of the power conversion system for TIG-welder is used PEMFC(Polymer Electrolyte Membrane Fuel Cell), and the power conversion system is comprised of full-bridge converter with function of boost converter and inverter welding source, in this paper. The proposed power conversion system which is power supply for TIG-welder was verified by computer simulations and experiments.

6061-T6 알루미늄 합금 판재에 대한 FSW와 TIG의 교차 용접부에서 용접 순서가 기계적 특성 및 미세조직에 미치는 영향

임영빈,이광진 한국기계기술학회 2021 한국기계기술학회지 Vol.23 No.2

알루미늄합금 6061-T6 판재에 대하여 마찰교반용접과 텅스텐 이너트 가스 용접의 교차 용접부의 미세조직과 기계적 특성에 있어서 용접 순서의 영향을 분석하기 위한 시험편을 성공적으로 제작하였다. FSW-ED 시험편이 다른 조합들보다 가장 좋은 기계적 특성을 나타내었다. 흥미롭게도, TIG-FSW ED 시험편이 FSW-TIG ED 시험편보다 높은 인장강도를 나타내었다. 용접부 경도의 경우, FSW 시편이 TIG-FSW 및 FSW-TIG 시험편보다 높은 값을 나타내었고, TIG-FSW 시험편이 FSW-TIG 시험편보다 높은 값을 나타내었다. FE-SEM을 이용한 인장 파면에 대한 관찰을 통하여, 모든 시험편에서 연성파괴를 나타내는 다양한 크기의 딤플들이 관찰되었다. FSW-TIG 시험편의 파면에서는 용융지(熔融池) 표면 영역에서 기공들이 관찰되는 반면, TIG-FSW 시험편에서는 기공의 형성은 관찰되지 않았다. 경도와 미세조직의 결과를 통해 TIG-FSW 공정이 FSW-TIG 공정보다 높은 인장강도를 확보할 수 있는 공정임을 확인하였다. The cross-welded joints for 6061-T6 aluminum alloy sheets were successfully manufactured through friction stir welding(FSW) and tungsten inert gas(TIG) welding methods to reveal the effect of welding sequence on microstructure and mechanical properties of the joints. Results revealed that FSW-ED joint shows maximum joint strength compare to other combinations. Interestingly, TIG-FSW joint shows much higher tensile strength than FSW-TIG joint. It is seen that the average hardness in SZ of friction-stir-welded specimen is comparatively higher than that of TIG-FSW and FSW-TIG joints. TIG-FSW specimen also shows higher hardness compare to FSW-TIG. Through FE-SEM observation for tensile fracture surface, various size of dimples clearly observed indicating ductile type of failure mode in all specimens. In case of FSW-TIG process, several voids were observed at the surface region of weld pool. On the contrary, no as such void formation has been observed in TIG-FSW process. The micro hardness and microstructural results clearly justify the higher tensile strength in TIG-FSW process.

두경부 종양에서 TIG1 유전자의 Hypermethylation

선동일,김민식,조광재,방충일,유영화,배민영,조승호 대한이비인후과학회 2005 대한이비인후과학회지 두경부외과학 Vol.48 No.2

Background and Objectives:Decreased expression and growth suppression of Tazarotene-Induced Gene 1 (TIG1) were reported in prostate cancer. In this study, we examined the possibility of TIG1 transcriptional silencing by hypermethylation in head and neck cancer. Subjects and Method:We extracted DNA and total RNA from five head and neck cell lines (O11, O12, O19, O22 and O28), and three prostate cell lines (PC3, LNCap and DU145). We checked the methylation status of TIG1 by methylation-specific PCR (MSP) and RT-PCR. We also examined primary cancer tissues of 32 head and neck cancer, 31 prostate cancer and 10 normal samples. Results:We found that all of five head and neck (100%) cell lines and two of three prostate (66.7%) cell lines were methylated. RT-PCR analysis confirmed the absence of TIG1 expression in six cell lines with methylation. We checked primary cancer by MSP and found TIG1 methylation in 16 of 32 (50%) head and neck cancers, and 17 of 31 (54.8%) prostate cancers. Normal head and neck and prostate tissues were free of methylation. Conclusion:Our results support the notion that methylation might be an important mechanism of TIG1 inactivation and a target event in head and neck cancer. (Korean J Otolaryngol 2005;48:247-52)

고숙련 용접사의 수동 TIG 공정 데이터 수집 및 모델링

오선호,김덕원,조상명 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

TIG용접은 아주 높은 품질이 얻어지므로 고가의 소재와 고급 부품의 조립에 주로 사용된다. 그러나 수동TIG용접의 경우, 한 손에는 아크를 일으키는 토치를 잡고, 다른 한 손으로는 용접봉을 용융지로 삽입하기 때문에, 양손 작업이 필요하여 고기능이 요구된다. 고숙련 TIG 용접사의 손동작을 디지털 측정하여 데이터로 확보하여 초보자의 수동용접 기능 훈련할 때나 실제 초보 수동용접사가 작업할 때 가이드 자료로 화면에 제시하는 AR은 큰 도움이 되는 것으로 밝혀졌다. 본 연구의 목적은 고숙련 TIG 용접사가 수동용접할 때의 위빙 데이터, 진행각과 아크길이 데이터를 측정하여 데이터 베이스로 작성하는 것이다. 실제로 8명의 고숙련 TIG 용접사가 수동 TIG용접으로 STS304 파이프 50A와 150A에 아래보기자세와 수평자세로 용접한 공정을 디지털로 전환하였다. 데이터의 측정을 위하여 TIG용접 모니터링 시스템(전류, 전압)과 2대의 용접전용 카메라(Top view, Side view) 및 이미지를 디지털로 전환하는 소프트 웨어 등을 사용하였다. 카메라를 이용하여 얻어진 동영상을 통해서 위빙 폭, 위빙 주기 등을 수집하여 데이터로 전환하였다. 용접 전압을 통해서는 아크길이를 판단하였다. 그 결과 8명의 고숙련용접사들은 그 기능의 차이가 현저하게 나타났다. 다만, 용접속도라고 하는 생산성 지표를 포함시키면 그 기능의 순위가 크게 바뀌는 경향이 나타났다. 아래 사진은 수동용접사가 좌우로 위빙할 때 그 폭을 측정하여 디지털로 전환하기 위한 이미지 모델이다. [사진은 본문 참조]

항파상풍 면역 글로부린의 효과

김옥준,하영록,최옥경,심호식,장석준,정성필,이경룡,박인철,김승환,구홍두,이정운 대한응급의학회 1994 대한응급의학회지 Vol.5 No.2

Despite the progress in treatment modality, tetanus still has a high mortality rate. However, the morbidity of tetanus can be decreased through proper prophylactic measures. Although Center for Disease Control(CDC) recommands Td or Td/TIG injection depending on prior immunization state and wound character, TIG alone is being injected to patient with open wound for tetanus prophylaxis in Korea. Therefore, we studied antitetanus antibody titers after injecting 250IU of TIG to evaluate TIG's duration of immunization effect, in vivo. TIG 250IU was injected to 42 healthy adult volunteers and their antitetanus antibody titers were measured at prior to TIG injection, 1 week and 4 weeks after infection. Antibody titers were measured by using ELISA assay with IMMUNOZYM-TETANUS and their results were verified by using the standard t-test. Mean antitetanus antibody titers were 0.167±0.031IU/mL, 0.211±0.031IU/mL and 0.186±0.031IU/mL at before injection, 1 week and 4 weeks after injection, respectively. Antibody titers showed significant difference between values at before injection and 1 week after injection. However, no difference was found between the values before injection and 4 weeks after injection. The practice of injecting TIG 250IU alone for prophylaxis has little effect on maintaining an increased antitetanus antibody titer until 4 weeks after injection.

STS 304의 TIG용접과 PLASMA용접에 따른 기계적 특성에 관한 연구

이광영 ( Lee Gwang Yeong ),정재욱 ( Jeong Jae Ug ),박원조 ( Park Won Jo ),허선철 ( Heo Seon Cheol ),이강길 ( Lee Gang Gil ) 경상대학교 해양산업연구소 2003 해양산업연구소보 Vol.16 No.-

TIG처리에 따른 하중비전달형 필렛용접부의 피로특성

정영화,경갑수,홍성욱,김익겸,남왕현,Jung, Young Hwa,Kyung, Kab Soo,Hong, Sung Wook,Kim, Ik Gyeom,Nam, Wang Hyone 한국강구조학회 2000 韓國鋼構造學會 論文集 Vol.12 No.5

이 연구에서는 하중비전달형 필렛용접부를 대상으로 순수휨상태에서 TIG 처리에 따른 피로강도 향상정도 및 피로특성을 정량적으로 평가하기 위해서 4점 휨실험을 실시하였다. 피로실험결과 용접후처리를 실시하지 않은 시험체는 국내 외에서 규정하는 피로강도등급을 만족하고 있고 TIG 처리한 시험체는 용접후처리를 실시하지 않은 시험체보다 $2{\times}106$회 피로강도가 상회하는 것을 알 수 있었다. 또한 비치마크실험결과 피로균열은 용접지단부의 비드접선각도 및 곡률반경이 최소로 되는 점에서 다발적으로 발생하며, 반타원형 균열로 성장, 합체되어 파단에 이르는 것을 확인할 수 있었다. 한편 유한요소해석결과 용접지단부의 응력집중계수는 용접지단부의 비드접선각도 및 곡률반경과 밀접한 관계가 있으며, 이 중에서 곡률반경이 용접지단부의 응력집중계수에 보다 큰 영향을 미치는 것을 알 수 있었다. 한편 파괴역학적 해석결과 a/t가 0.4 이하인 경우에 기하학적형상보정계수가 균열보정계수에 가장 지배적인 영향을 미치는 인자임을 알 수 있었다. 또한 유한요소해석결과로부터 산정한 응력확대계수범위와 피로균열성장속도의 관계식으로부터 피로수명을 비교적 정확하게 산정할 수 있었다. In this study, the 4-point bending test has been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for non load-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strength of as-welded specimens has been satisfied the grade of fatigue strength prescribed in specifications of domestics and AASHTO & JSSC, and fatigue strength at $2{\times}106cycles$ of TIG-dressing specimens has been increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks have been occurred at several points, where the radius of curvature and flank angle in the weld bead toes are low, and grown as semi-elliptical cracks, then approached to fracture. As a result of finite element analysis, stress concentration factor in weld bead toes has been closely related to the flank angel and radius of curvature, and between these, the radius of curvature has more largely affected in stress concentration factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has been largely affected on stress gradient correction factor in case a/t is below 0.4. From the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

Corrosion Characteristics of Welding Zones by Laser and TIG Welding of 304 Stainless Steel

( Kyung Man Moon ),( Myung Hoon Lee ) 한국부식방식학회(구 한국부식학회) 2010 Corrosion Science and Technology Vol.9 No.6

Two types of welding methods were performed on austenitic 304 stainless steel: laser welding and TIG welding. The differences of the corrosion characteristics of the welded zones from the two welding methods were investigated with electrochemical methods, such as measurement of the corrosion potential, polarization curves, cyclic voltammogram, etc. The vickers hardness of all laser-welded zones (WM:Weld Metal, HAZ:Heat Affected Zone, BM:Base Metal) was relatively higher while their corrosion current densities exhibited a comparatively lower value than those which were TIG welded. In particular, the corrosion current density of the TIG-welded HAZ had the highest value among all other welding zones, which suggests that chromium depletion due to the formation of chromium carbide occurs in the HAZ, which is in the sensitization temperature range, thus it can easily be corroded with an active anode. Intergrenular corrosion was also observed at the TIG-welded HAZ and WM zones. Consequently, we can see that corrosion resistance of all austenitic 304 stainless steel welding zones can be improved via the use of laser welding.

용접지단부 TIG처리에 의한 피로강도향상 및 피로특성

정영화,김익겸,남왕현,장동휘 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A

The 4-point bending tests have been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for nonload-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strengths of as-welded specimens have satisfied the grade of fatigue strength prescribed in specifications of korea, AASHTO and JSSC. Fatigue strength at 2 million cycles of TIG-dressing specimens have increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks occurred at several points, where the radius of curvature and flank angle in the weld bead toes were low, and grew as semi-elliptical cracks, then approached to fracture, As a result of finite element analysis, stress concentration factor in weld bead toes has closely related to the flank angle and radius of curvature, and between these, the radius of curvature has more largely mechanics approaches, the crack correction factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has largely affected on stress gradient correction factor in case a/t is below 0.4 from the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.

용접지단부 TIG처리에 의한 피로강도향상 및 피로특성

정영화(Jung Young Hwa),김익겸(Kim lk Gyeom),남왕현(Nam Wang Hyone),장동휘(Chang Dong Huy) 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.1

The 4-point bending tests have been performed in order to estimate the effect of TIG-dressing on fatigue strength and fatigue characteristics quantitatively for nonload-carrying fillet welded joints subjected to pure bending. As a result of fatigue tests, fatigue strengths of as-welded specimens have satisfied the grade of fatigue strength prescribed in specifications of korea, AASHTO and JSSC. Fatigue strength at 2 million cycles of TIG-dressing specimens have increased compared with as-welded specimens. As the result of beachmark tests, fatigue cracks occurred at several points, where the radius of curvature and flank angle in the weld bead toes were low, and grew as semi-elliptical cracks, then approached to fracture, As a result of finite element analysis, stress concentration factor in weld bead toes has closely related to the flank angle and radius of curvature, and between these, the radius of curvature has more largely mechanics approaches, the crack correction factor than flank angle. As a result of fracture mechanics approaches, the crack correction factor of test specimens has largely affected on stress gradient correction factor in case a/t is below 0.4 from the relations between stress intensity factor range estimated from FEM analysis and fatigue crack growth rate, fatigue life has been correctly calculated.