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임정인,김형순,유리알,김은희,공호영 병원간호사회 2014 임상간호연구 Vol.20 No.3
Purpose: To improve professional intensive care by analyzing admission causese, causes of death, disease conditions, and treatment processes in patients with hematological malignancies admitted to intensive care units (ICUs) in South Korea. Methods: This was retrospective study approved by IRB, and conducted on admission with 559 adults, in the hematology ICU of a hospital located in Seoul. The study was carried out from April 2009 to March 2012. Data were analyzed using SAS. Results: Pneumonia was the most frequent cause of ICU admission and death, followed by sepsis. The consition at discharge was death (53.6%), recovery (39.9%), or hopeless (5.1%). Mortality of patients in states of incomplete remission was higher than that of patients with complete remission and of patients with multifle myeloma, severe aplastic anemia, and lymphoam. Conclusion: Results show that pneumonia and sepsis are the most frequent causes of ICU admission and for the death of patients with hematological malignancies. The most frequent causes of ICU admission and for the death of patients with hematological malignancies. the most frequent status at discharge of patients with hematological malignancies was death (53.6%), with mortality of patients at Incomplete Remission status, of mechanically ventilated patients, and of patients on continuous renal replacement therapy (CRRT) being higher than others.
1180MPa급 강판 대상 점용접 및 레이저 용접 대체를 위한 다양한 아크 플러그 형상 용접부 접합강도 및 접합특성 비교 연구
박영도,김두영,아룬 랄라찬,공호영,김경영,신지영,허민 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Advanced high strength steels have been used in automotive structures due to their superior mechanical properties. Lap joining of these sheets can be done using different welding processes. In this study lap joining of 1180 MPa steel sheet of thickness 1.0 mm was done using resistance spot welding (RSW), Arc plug welding and Laser welding processes. To have a comparative evaluation between the resultant welds, similar effective interfacial weld size was obtained for all joining and tensile shear performance of the welds was conducted. Resistance spot welding was found to be more productive with highest mechanical properties among all processes for welding 1180 MPa steel sheets. Additionally, the lap shear fracture modes of these joints were analyzed and joint characteristics that affecting the fracture behavior was discussed.
시트 백 프레임 적용 1180 MPa 급 강판 아크 플러그 용접부 적용 솔리드 와이어 종류에 따른 접합부 미세조직 및 파단특성 비교
박영도,아룬 랄라찬,김두영,공호영 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11
최근 전기자동차의 보급이 확대 및 차량 경량화를 위한 차체 및 샤시 부품 고강도 강판의 적용이 증가함에 따라 자동차 시트 부품 중 충돌 강성이 요구되는 백 프레임에 적용 된 기존 아크플러그 용접의 용접부 불량에 따른 차량 내구성 저하가 큰 문제가 되고 있다. 또한 기가급 고강도 강판을 시트 백 프레임에 적용이 검토되면서 아크 플러그 용접부에 기존 연강 및 50 Kg급 고장력강용 솔리드 와이어 적용 시 용접부 품질 및 고강도 와이어 적용 필요 여부 등에 대한 연구가 요구되며 이에 따른 용접부 물성 비교 평가가 요구되었다. 적용된 용접와이어는 AWS 규격의 ER-70S 및 ER-110R 두가지이며 440 MPa급 부터 1180 MPa급 강재에 6.0 mm 직경의 원형 플러그 용접을 각각 적용 후 용접부 기계적 특성 및 전단인장 시험 후 파단특성을 평가하였다. 590 MPa급 이상의 강재에서는 고강도 ER-110 와이어 적용 시 약 1.0 kN 전후의 전단인장 강도의 증가가 확인되었으나 파단위치는 ER-70 와이어의 경우 용착 금속부에서 발생 한 반면 ER-110 와이어의 경우 모두 조대열영향부로 파단 위치가 변경되었다. 따라서 원형 아크 플러그 용접의 경우 전단인장 시험 시 전단인장 하중 방향의 원형 용접부 국부적인 위치에서 응력 집중이 발생하므로 기가급 강재의 경우 고강도 와이어 적용 시 용착금속부의 경도가 증가하여 전단인장 시험 시 응력집중을 지탱 가능하므로 파단이 대부분 열영향부에서 발생하는 것으로 판단된다.
TWB 핫스탬핑 공법 적용을 통한 일체형 사이드아우터 부품 개발
김소연(Soyoun Kim),공호영(Hoyoung Kong) 대한용접·접합학회 2015 대한용접·접합학회지 Vol.33 No.6
In the automotive industry, TWB hot stamping process is broadly adapted to reduce weight of the car and improve fuel efficiency. However, the process faces a problem of weakened strength of the welded zone after hot stamping process, due to the fact that Al-Si elements of the coating layer penetrating the welded zone. In this study, filler wires with high percentages of carbon and manganese is adapted during laser welding process to secure the strength of the fusion zone. In addition, wire feeding speed and laser welding speed are optimized by sample test.
박시영(Siyoung Park),김도회(Dohoi Kim),공호영(Hoyoung Kong) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
The B-pillar with TRB (Tailor Rolled Blank) is developed for weight reduction of car body. The reinforcements in the typical B PLR can be replaced by one TRB part which has continuous thickness changes. TRB thickness profile is modified for satisfying IIHS side impact test. The free fall tests have been carried out. The results show that the new B PLR with TRB is 15% lighter than typical structure and has equivalent crashworthiness.
Studies on the Coating Materials for Forming Dies of Advanced High Strength Steel Sheets
Sungchul Cha(차성철),Hoyoung Kong(공호영),Iksoo Kim(김익수),Kunuk Park(박건욱),Hyundal Park(박현달) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
To increase the safety and lighten the weight of car body and chassis, the application of advanced high strength steel (AHSS) is being rapidly expanded. Current forming dies with thermal diffusion (TD) of vanadium carbide or coatings (AlTiCrN+MoS2, TiAlN) don’t have enough wear resistance and durability. The coatings shall have complex material properties, e.g. wear, temperature, fatigue resistance and low friction property. The main concept of coating and layer development is to add the low friction property through carbon addition to temperature resistant elements. The toughness, fatigue resistance and bonding are realized through nitrided layer, CrN or TiN and multilayer structure. Total 18 coatings are compared and discussed in this work. As conclusion, TiAlCN and AlTiCrN+CN show the competitive solutions.
ARUN LALACHAN,SIVA PRASAD MURUGAN,김경영,신지영,김두영,공호영,박영도 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Efforts to reduce the vehicle weight and improve the crash performance have led to the increased application of advanced high strength steels (AHSS) into the automotive architecture. Although resistance spot welding and laser welding are mainly used for joining thin sheets in the car body. However, the joining methods poses a problem of reachability in chassis part. To overcome this issue, arc plug welds are invented as a novel method for joining steel sheets in chassis part. To address this shift in joining procedure to arc plug welds, consequently propelled the need to the understanding of the plug weldability of various steel sheets. In this study, to investigate the plug weldability, a comparative evaluation of six steel sheets ranging from 440MPa to 1500MPa with similar thickness of 1.0 mm has been done by using ER110S wire in 8:2Ar CO2 atmosphere with a hole of 6 mm. The mechanical properties and microstructure of these arc plug welds with similar effective interfacial weld diameter of 6mm are detailed. It was found that the AHSS consistently achieved high tensile shear strength compared to the conventional steel grades. The differences in failure mode are attributed due to the HAZ softening and weld metal hardness.
Study of optimal weld design for arc plug welding of advanced high strength steels
ARUN LALACHAN,SIVA PRASAD MURUGAN,김경영,신지영,김두영,공호영,박영도 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11
The incorporation of Advanced high strength steels (AHSS) into the automotive architecture have led to reduction of the vehicle weight and improve the crash worthiness. Majorly Resistance spot welding and laser welding have been employed for joining car-body joining. However, these joining techniques poses an issue of reachability in chassis part. To resolve this issue, arc plug welding was introduced as a novel method. The transition of the welding process to arc welding process requires knowledge of the weldability of the arc plug welding. In this study, an experimental method for the selection of the optimal plug welding shape in 1180MPa AHSS with the equivalent effective weld area to the 6.0mm nugget diameter in spot welds was performed. The arc plug welding was performed with 3 different plug hole shapes namely circle plug (6φ) and elliptical plug (4x9 and 3x12mm) to define the optimum weld shape design for plug welding. The optimized welded sample were subjected for mechanical characterization like hardness and Tensile shear performance. The experimental results confirm that the Elliptical plug welding of 4x9 hole showed 68% increase in TSS performance with the low strength wire (ER70S-6) than the resistance spot welding counterparts and poses a possible replacement for securing weld robustness.