고려 俗樂歌詞의 세계관 연구

조형호 한국어문연구학회 1986 한국어문연구(구 계명어문학) Vol.2 No.-

중이염 수술에서 실리콘을 이용한 골부 외이도 재건술

조형호,윤태미,이동훈,장철호,조용범 대한이비인후과학회 2005 대한이비인후과학회지 두경부외과학 Vol.48 No.12

후두기관 협착증에 대한 확대 후두기관 성형술

조형호,조재식,임상철 대한이비인후과학회 2003 대한이비인후과학회지 두경부외과학 Vol.46 No.9

Background and Objectives:Laryngotracheal stenosis produces complications of respiratory and phonation difficulties and is one of the most troublesome diseases in the otolaryngological field. The purpose of this study is to determine the therapeutic effectiveness of augmentation laryngotracheoplasty for laryngotracheal stenosis as an operative management. Method:The authors retrospectively studied 16 cases of augmentation laryngotracheoplasty patients for the success rate, graft material, type of stent, number of surgery, and duration of treatment. Results:The sucess rate was 68.7% (1 out of 16 cases). Thre out of 5 cases which failed treatment were under 15 years of age. Decanulation was possible at 8.45 months (2- 45 months) postoperatively on the average and the frequency of surgery was 4.36 times (2- 13 times) on the average. There was no complication such as infection and necrosis. Conclusion:Our results show that augmentation laryngotracheoplasty is an aceptable option for the treatment of laryngotracheal stenosis, but needs multiple surgery and long time to be decannulated. The suces rate of the augmentation laryngotracheoplasty in children is relatively low and a more agresive approach could be selected. We conclude that augmentation laryngotracheoplasty in adult is a safe and effective procedure without major (Korean J Otolaryngol 2003 ;46 :775-9)

포트홀 형상 변화를 고려한 Al멀티셀 튜브 압출공정 해석

조형호,이정민,김동환,김병민 대한기계학회 2005 大韓機械學會論文集A Vol.29 No.8

Prediction of Welding Pressure in the Non Steady State Porthole Die Extrusion of Al7003 Tubes

조형호,김병민,Jung-Min Lee,Seon-Bong Lee 한국정밀공학회 2003 International Journal of Precision Engineering and Vol.4 No.3

This paper describes a numerical analysis of a non-steady state porthole die extrusion, which is useful for manufacturing long tubes with a hollow section. Materials divided through several portholes are gathered within a chamber and are then welded under high pressure. This weldability classifies the quality of tube products and is affected by process variables and die shapes. However, porthole die extrusion has been executed based on the experience of experts, due to the complicated die assembly and the complexity of metal flow. In order to better assist the design of die and to obtain improvement of productivity, non-steady state 3D FE simulation of porthole die extrusion is required. Therefore, the objective of this study is to analyze the behavior of metal flow and to determine the welding pressure of hot extrusion products under various billet temperatures, bearing length, and tube thickness by FE analysis. The results of FE analysis are compared with those of experiments.

AI-Si 합금의 열간압출에 있어서 압출압력에 관한 연구

조형호,Jo, Hyeong-Ho 한국재료학회 1994 한국재료학회지 Vol.4 No.7

현재까지 잘 알려진 압출이론식이 생산현장에 응용될 수 있는가를 조사하기 위하여, Al-Si합금을 대상소재로 하여 각 압출이론식에 나타난 유도응력 $K_f$, 변형저항 $K_w$ , Dead Metal Zone(DMZ)의 경각($\alpha$)등을 측정하였으며, 이들 값을 이용하여 최대압출력을 계산하였다. 550ton의 압출기를 이용하여 측정한 최대 압출력과의 비교분석을 행하였으며, 그 결과 이론식에 의해 최대압출력을 계산하기 위해 측정된 유동응력 및 변형저항 값은 신뢰할 수 있을 것으로 사료되었는데, 이것은 0.5이하에서 결정된 변형효율 $\eta _f$로서 판단 할 수 있었다. 최대 압출력은 Si함량이 증가할 수록 증가하게 되나, 압출온도가 증가할 수록 감소하고 있음을 알 수 있었다. Siebel식으로부터 계산된 최대압출력은 본 실험을 통하여 얻어진 최대압출력에 비교적 근접하고 있으나. Geleji식으로부터 계산된 최대압출력은 DMZ의경각 $\alpha$가 $50^{\circ}$일 경우 , 본 실험에 의해 얻어진 실제의 최대압출력에 급접하고 있었다. Geleji의 식은 DMZ의 경각에 매우 민감하고, 대상재료마다. DMZ를 일일이 측정해야 하는 번거로움 때문에 생산현장에서는 Siebel의 식을 이용하는 것이 보다 편리할 것으로 사료된다. To investigate that the theoretical formulas for extrusion forces are applicable to the manufacturing plant, the maximum extrusion forces were calculated from Siebel's and Geleji's formulas and also measured using 550 ton extrusion press. Parameters such as flow stress, $K_f$, angle of dead metal zone, $\alpha$ were obtained experimentally in order to calculate the maximum extrusion forces by the the theoretical formulas, and it was showed that the results were reliable as the deformation efficient factor, $\eta _f$ was determined to be less than 0.5. The maximum extrusion forces calculated from Siebel's formula and Geleji's formula for the angle of dead metal zone, $\alpha = 50^{\circ}$ were approached to the experimental results. However, it was found that Siebel's formula is more useful to apply to the manufacturing plant.

인간 유양돌기 골수 유래 간엽줄기세포의 획득 및 신경세포로의 분화

조형호,정한성,장수정,박종성,조휴채,장철호,조용범 대한이비인후과학회 2008 대한이비인후과학회지 두경부외과학 Vol.51 No.5

Reports of neural differentiation of mesenchymal stem cells suggest the possibility that these cells may serve as a source for stem cell-based regenerative medicine to treat neurological disorders. The purpose of this study was to generate neural cells by differentiation of bone marrow-derived mesenchymal stem cells that isolated from human mastoid process. Materials and Method:Human mesenchymal stem cells (hMSCs) isolated from human mastoid process bone marrow during mastoidectomy for chronic otitis media surgery were characterized using fluorescence-activated cell sorter. Induction of neural differentiation from hMSCs was performed using mitogenic factors (basic fibroblast growth factor, epidermal growth factor, forskolin, isobutylmethylxanthine), and the characterization of differentiated hMSCs was performed using immunohistochemistry, RT-PCR and whole cell patch clamp technique. Results:hMSCs from bone marrow of mastoid process were isolated and cultured. Differentiated cells from hMSCs expressed mRNA transcripts for neuron specific markers, TUJ1 and neurofilament proteins (NF-L, NF-M) as determined by RT-PCR, and neuron specific markers, suhc as NeuN, TUJ1, microtubule- associated protein-2 (MAP2) and glial fibrillary acidic protein by immunohistochemistry. These cells showed voltagedependent sodium currents that was blocked by tetrodotoxin. Conclusion:hMSCs, which were isolated from human mastoid process bone marrow, were one of the good sources for stem cell-based regenerative medicine to treat neurological disorders. (Korean J Otorhinolaryngol-Head Neck Surg 2008;51:422-8)

$SiC_p/6061 Al$ 복합재료의 압출가공에 있어서 압출특성

조형호,Jo, Hyeong-Ho 한국재료학회 1994 한국재료학회지 Vol.4 No.8

분말야금법으로 제조된 $SiC_{p}$/6061 Al 복합재료의 열간 압출가공에 있어서 압출성에 미치는 빌렛의 특성과 압출조건의 영향에 대하여 조사하였다. 압출가공성의 난이도를 판단 할 수 있는 기준이 되는 최대압출력과 변형저항 값($K_{w}$)은 350ton 압출기를 이용한 압출압력의 측정과 Watanabe등의 경험식에 의해 도출되었다. 6061Al합금기 복합재료 빌렛의 전단변형저항고 압출압력은 강화재($SiC_{p}$)의 부피분율이 증가함에 따라 증가하고 있으나, 증가되는 비율은$SiC_{p}$인 경두가 $SiC_{w},Al_{2}O_{3f}$/보다 작았다. 강화입자 크기가 작을 수록 변형저항 값이 증가하였고 압출성도 양호하였다. 변형저항 값의 증가는 기지금속의 가공경화에 기인하며, 최대압출력을 나타내는 피이크는 강화재의 입자가 미세할 수록, 즉 가공경호가 클 수록 뾰족한 형상을 나타내었다. 압출온도가 증가할 수록 변형저항 값이 낮아져서 작은 압출력으로도 복합재료의 압출이 가능하나, $500^{\circ}C$이상인 경우 압출재 표면에 극심한 tearing현상이 발생하였다. In order to elucidate the extrusion characteristics of $SiC_{p}$/6061 Al composite, defomation resistance, $K_{w}$ was determined using the empirical formula suggested by Watanabe et al, and also extrusion pressure was measured using the extrusion press with a capacity of 350 ton. The $K_{w}$ which are propotional to extrudability, was increased with increasing volume fraction of reinforcement, $SiC_{p}$, but decreased with increasing the particle size. The peaks of maximum extrusion pressure in curves of extrusion force vs ram stroke were changed sharply with decreasing the particle size. The elevated extrustion temperature resulted in the decreased $K_{w}$ and extrusion pressure, but caused the surface tearing of extrusion composite bars. The results showed that extrudability of the composite billets is depend on the extrusion conditions as well as the characteristics of reinforcement, $SiC_{p}$.

알루미늄 압출산업 동향과 기술개발 방향

조형호,조훈 한국소성가공학회 2003 한국소성가공학회 학술대회 논문집 Vol.2003 No.10

고려 속락가사(俗樂歌詞)의 세계관 연구

조형호 한국어문연구학회(구 계명어문학회) 1986 한국어문연구(구 계명어문학) Vol.2 No.-