이음면 이격이 확장형 단부판 이음부 성능에 미치는 영향에 대한 실험적 연구

김철환,이명재,김희동,김사빈,Kim, Cheol Hwan,Lee, Myung Jae,Kim, Hee Dong,Kim, Sa Bin 한국강구조학회 2016 韓國鋼構造學會 論文集 Vol.28 No.6

This study is experimental research for the effect of gap at the end plate on the performance of extended end-plate type splice. For this research, simple beam type specimens by using extended end-plate type splice are planned. Main variables are the initial gap between end-plates, the installation of finger shim plate before the installation of high tension bolts, the final gap between end-plates, and the installation of finger shim plate after the installation of high tension bolts. The static loading tests results show that the maximum bending strength of splice is not dependent on the gap, but the vertical displacement, initial stiffness and elastic stiffness are affected by the gap. In addition to that, the possibility of brittle fracture is increased when the torque of high tension bolt is used to control the gap. Thus, careful consideration is needed in this case. 두본 연구는 실험적인 방법을 통하여 단부판 이음부의 이음면에서 초기 오차로 발생하는 이격이 이음부의 내력 및 거동에 미치는 영향을 평가한 연구이다. 이를 위하여 총 5가지의 단순보형 실험체를 확장형 단부판 이음부를 이용 계획하였고 주요 변수로는 이음면 초기 이격(gap) 여부, 고력볼트 채결 전 끼움판(finger shim plate) 설치 유무, 고력볼트 체결 후 이음면 이격, 고력볼트 채결 후 끼움판 삽입 여부를 적용하였다. 정적가력실험 결과 이음판의 이격은 이음부의 최대휨강도에 미치는 영향은 제한적이나 수직변형과 초기 및 탄성강성에는 영향을 미치는 것으로 나타났으며, 이격을 제어하기 위해 고력볼트 장력을 이용할 경우 고력볼트의 취성파괴 우려도 있는 것으로 나타나서 이들에 대한 충분한 고려가 필요할 것으로 판단된다.

2영역 모델을 이용한 EGR사용 직접분사식 디젤엔진의 Nox생성예측

김철환,이진호,전광민,이교승,Kim, Cheol-Hwan,Lee, Jin-Ho,Chun, Kwang-Min,Lee, Kyo-Seung 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.3

In this study, numerical calculation is carried out to investigate the influence of injection timing, fuel amount, intake $O_2$ concentration, and EGR on Nitric Oxide(NO) formation using a two-zone model in a diesel engine. Results can be summarized as follows. The NO formation is very sensitive to the burned gas temperature, so multi-zone model must be applied to combustion process to predict the burned gas temperature exactly. Since the burned gas temperature increases rapidly during the premixed combustion, most NO is formed within 20 crank angle degrees after ignition. As the injection timing is retarded, the combustion occurs later in the expansion process which causes the decrease of burned gas temperature and, as a result, NO formation decrease. The increase of fuel amount results in the increase of earlier formation of NO in the engine. As the intake $O_2$ concentration increases, the maximum pressure and burned gas temperature increase due to activate combustion. And, [O] mole fraction of equilibrium combustion products also increase. Therefore NO exponentially increases. If exhaust gas is recirculated, the burned gas temperature decreases which results in NO decrease. If exhaust gas is cooled, more NO can be decreased.

Strain-induced Local Transport Properties in Epitaxial Pr0.7Ca0.3MnO3 Thin Films

김철환,Y. H. Jang,H. B. Moon,J. W. Kim,조진형 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

Pr0.7Ca0.3MnO3 (PCMO) thin films have been deposited on SrTiO3 (STO) substrates by using a pulsed laser deposition (PLD) method. By changing the in-situ annealing condition after the film deposition, we were able to prepare two different sets of films, where coexistence of both strained and relaxed structures was obtained using a synchrotron X-ray diffraction. We observe that the density of the strained structure depended on the cooling condition, as observed from the mesh scan of HL reciprocal lattice. In addition, structural characterizations of the films were carried out, and the local transport properties are discussed in terms of the strain-induced misfit at the grain boundary.

전외측대퇴유리피판 (Anterolateral Thigh Free Flap)을 이용한 구강안면부 결손의 재건

김철환,방대연,황승연,Kim, Chul-Hwan,Bhang, Dae-Yeon,Hwang, Seung-Yeon 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6

Recently, the anterolateral thigh(ALT) flap, based on the septocutaneous vessels or musculocutaneous perforators from the descending branch of the lateral circumflex femoral artery has gained popularity in head and neck soft-tissue reconstruction. It has some advantages in free-flap surgery with respect to the radial forearm free flap, such as low donor site morbidity, availability of different tissues with large amounts of skin, adaptability as a sensate or flow-through flap (with the possibility of harvesting a long pedicle with a suitable vessel diameter). Moreover, the thickness of the flap is adjustable until the subdermal fat level, allowing it to be used as a thin or ultrathin flap. This clinical cases are ALT free flap reconstructions without functional impairment of the donor limbs (transitory and permanent) based on anastomosis with superficial temporal arteries and veins in patient of huge resection defect on face, lip and tongue.

Investigations of the Structural, Thermal, and Magnetic Properties of Ca3-xYxCo2O6

김철환,김복기,A. I. Ali,백현종,조진형,K. H. Kim,S. H. Park 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

We have studied the structural, thermal, and magnetic properties of Y-substituted Ca3Co2O6. The parent system, Ca3Co2O6, undergoes two magnetic transitions due to the competition between the intrachain ferromagnetic interaction and the interchain antiferromagnetic interaction. There is a notable variation in both inter/intrachain interactions as x increases up to 1.0 in Ca3.xYxCo2O6. A gradual, but unique, change in the ground state from ferrimagnetic to nonmagnetic has been observed in the heat capacity and in the ac magnetic susceptibility, and is also reflected in the change in the lattice constant, as determined from the X-ray measurement. The origin of experimental results is with the spin configuration of the Ca3.xYxCo2O6 by using a crystal-field-splitting model.펥궔띎 We have studied the structural, thermal, and magnetic properties of Y-substituted Ca3Co2O6. The parent system, Ca3Co2O6, undergoes two magnetic transitions due to the competition between the intrachain ferromagnetic interaction and the interchain antiferromagnetic interaction. There is a notable variation in both inter/intrachain interactions as x increases up to 1.0 in Ca3.xYxCo2O6. A gradual, but unique, change in the ground state from ferrimagnetic to nonmagnetic has been observed in the heat capacity and in the ac magnetic susceptibility, and is also reflected in the change in the lattice constant, as determined from the X-ray measurement. The origin of experimental results is with the spin configuration of the Ca3.xYxCo2O6 by using a crystal-field-splitting model.

방산물자 수출 활성화 방안

김철환,Kim, Cheol-Hwan 한국방위산업진흥회 2003 國防과 技術 Vol.- No.291

현재 방산업체 위주의 방산물자 수출 수주활동은 한계에 직면하고 있으며 우리가 향후 수출하려는 장갑차, 전차, 초등/고등 훈련기, 신형 자주포, 함정 등과 같은 고가의 시스템 장비는 방산업체의 노력만으로는 수주성공이 어려워 정부의 적극적인 지원이 요구된다고 할 수 있다. 그 동안 우리 정부에서도 방산물자 수출의 중요성과 정부의 역할을 인식하고 상당한 노력을 기울여 왔음에도 불구하고 아직까지도 정부차원의 방산물자 수출전담 지원기구가 없으며, 방산물자 수출을 위한 금융지원제도의 미약, 국제 방산 협력의 미흡, 독자적인 수출전략 품목의 부족, 그리고 해외시장에 대한 정보획득 제한 등의 문제점으로 인해 정부.군.업체가 공동으로 수출 마케팅을 수행하기 어려운 상황이다.

구강암 수술 및 재건 환자에서의 C-Reactive Protein 수치의 변화

김철환,황승연,Kim, Chul-Hwan,Hwang, Seung-Yeon 대한악안면성형재건외과학회 2010 Maxillofacial Plastic Reconstructive Surgery Vol.32 No.5

Purpose: The aim of this study is that we evaluate the change of the White Blood Cell(WBC) count, Absolute Neutrophil Count (ANC), Erythrocyte Sedimentation Rate (ESR) and C-reactive Protein (CRP) values, and try to make standardization for postoperative sequels before and after the oral cancer resection and reconstructive surgery. Materials and Methods: The study was comprised of 34 patients (male 15, female 19) who were diagnosed as an oral cancer and had performed ablation and reconstructive surgery at Dankook university dental hos-pital. Each blood specimen was collected from patients and estimated WBC count, Neutrophil count, ESR, CRP on first, third, fifth, seventh day efore and after surgery and analyzing inter relationship between each value. Classifying Group I (resection with reconstructive surgery patients) and Group II (resection without reconstructive surgery patients). Also classifying group A (below 4 hours of operation time), Group B (4 to 8 hours of operation time), Group C (above 8 hours of operation time), each group was analyzed and compared. The Following results were induced. Results: (1) In coefficient of correlation, the CRP and WBC has highest value except WBC count and Neutrophil count. (2) There was no significant difference any lapse in the progress between Group I and II of WBC count, Neutrophil count, but the CRP shows statistically higher level in group I than group II at immediate postoperative day, and 1 to 5 days after surgery. (3) There is no significant difference any lapse in the progress between Group A, B, C of WBC count, Neutrophil count, but CRP shows statistically significant difference in 1 day, 3 days after surgery Conclusion: It should be suggested that, determination of CRP is most valuable parameter for postopera-tive management and determination of postoperative clinical changes than other parameter such as WBC count, neutrophil count, and ESR values in oral cancer patient after resection and reconstructive surgery, based on the results of this study.

항공기산업의 CALS 체제 도입방안

김철환,Kim, Cheol-Hwan 한국항공우주산업진흥협회 1996 航空宇宙 Vol.40 No.-

항공기산업의 CALS 체제 도입방안

김철환,Kim, Cheol-Hwan 한국항공우주산업진흥협회 1996 航空宇宙 Vol.39 No.-

CALS의 개념은 과거에는 군의 무기 체계를 지원하는 개념에서 출발하였으므로 일반적으로 "무기체계의 설계, 제작 및 군수유통체계 지원을 위해 디지털 기술의 통합과 정보 공유를 통한 신속한 자료처리 환경 구축"으로 정의할 수 있다. 그러나 현재는 "제품의 생산으로부터 폐기에 이르는 모든 활동을 디지털 정보기술의 통합을 통해 구현하는 산업화 전략"이라는 표현으로 확장되고 있으며, 제품의 총체적 관리를 위한 기술 정보 통합 전략이라고 표현되고 있다.

제3세계의 조기경보

김철환,Kim, Cheol-Hwan 한국방위산업진흥회 1987 國防과 技術 Vol.- No.104