인발 성형 공정을 이용한 carbon-glass hybrid composite 제작

박상윤,최원종,강길호,문초록,김세영 한국항공대학교 항공우주산업기술연구소 2002 航空宇宙産業技術硏究所 硏究誌 Vol.12 No.-

단면이 일정한 구조용 복합재료 제조공정에 널리 사용되고 있는 pultrusion 공정을 이용하여 glass-carbon fiber hybrid composite을 제조하였다. 열분석을 통하여 모재의 경화온도와 경화시간을 분석한 후 금형의 온도와 pulling speed를 결정하였다. 다양한 섬유 비율의 hybrid composite를 제작하였으며 flexural modulus를 측정한 결과 rule of mixture를 이용한 예상치 보다 높은 값을 보였다. Glass-carbon hybrid composite was manufactured by pultrusion process. The major processing conditions such as temperature of heating die and pulling speed have been fixed from thermal analysis results. Hybrid composites with various carbon fiber content were manufactured and flexural modules of each hybrid composite as measured. Compare with rule of mixture, positive hybrid effect was observed.

로케트 工學에 관한 硏究 : 第1報 : 亞音速 亂流流動에서 飛行翼模型의 剝離現象 Ⅰst Report : Separation of Airfoils in Subsonic Turbulent Flow

朴煥奎,金鍾一,金鎭興,李茂錫,朴吉文,鄭洛奎,李行男,李東起 조선대학교 동력자원연구소 1984 動力資源硏究所誌 Vol.6 No.2

Separation, pressure and velocity distributions were studied fully developed two dimensinonal, incompressible flow over a flat airfoil in subsonic wind tunnel. Velocity and turbulence were measured with a two channel constant temperature hot wire anemometer and pressure with a pitot tube and pressure tranducer system. The experimental results were obtained as follow: (1) Turbulent intensity of shear layer just outside the separation point is considered to affect the size of separation bubble. (2) Static pressure coefficient is separated into three regions according to its value change. (3) Separation point is varied with the change of attack angle. (4) Velocity distributions and boundary layers normal to airfoil surface are changed as variation of attack angle of airfoil.

경부에 발생한 의인성 괴사성 근막염의 증례

문철,권혁도,이동근,박경옥,성길현,이재은 大韓顎顔面成形再建外科學會 1994 Maxillofacial Plastic Reconstructive Surgery Vol.16 No.1

Necrotizing fascitis is a severe soft tissue infection characterized by extensive necrosis of superficial fascia, suppurative fascitis, vascular thrombosis, widespread undermining of surrounding tissues. Accociated systemic problems are widespread undermining of surrounding tissues, Accociated systemic problems are common, with chronic alcoholism and diabetes being most prominent. Most commonly this disease presents in the extremities, trunk, and perineum. Necrotizing fascitis of dental origing is rare and its fulminating clinical course is not well documented in the dental literature. The present report is a case of necrotizing fascitis following vital extirpation of the pulp in a patient with uncontrolled diabetes mellitus and liver cirrhosis. Originally throught to be caused by hemolytic streptococcus organism or stphylococcus aureus, advances in anaerobic culturing have shown it to be a synergistic bacterial infection involving aerobic and ovligate anaerobes. it is relatively rare in relatively rare in haea and neck regions. If it was not diagnosed and treated in early stages, necrotizing fascitis can be potentially fetal, with a mortality rate approaching 40%. It's treatment requires early recognition, prompt and aggressive surgical debriment and proper supportive cares, such as, antibiotic therapy, fluid resuscitation and correction of metabolic and electrolyte disorder, resolving of the underlying systemic disease. Recently, we experienced two cases of necrotizing fascitis in cervicofacial region, One patient was 60 years old male with uncontrolled Diabetes Mellitus and other patient was 48 years old with steroid therapy during 30 years. Local surgical wound healing was successful but, patients were died after admission, because of lung abscess, gastrointestinal bleeding, septic shock and respiration hold.

4각덕트의 입구영역에서 난류진동유동의 유동특성에 관한 연구

박길문,조병기,고영하 조선대학교 동력자원연구소 1996 動力資源硏究所誌 Vol.18 No.1

The flow characteristics of developing turbulent oscillatory flow are investigated experimentally in the entrance region of a square duct (40 ㎜ X 40 ㎜ and 4,000 ㎜). Experimental results of mean velocity profiles, turbulence intensity and entrance length are measured by using a hot-wire anemometer system together with data acquisition and processing systems. For turbulent oscillatory flow, the turbulent components in the velocity waveforms increase as the dimensionless transverse position approaches the wall. Velocity distribution are not change fully developed region. Inflow and outflow are nearly symmetrical form in the fully developed region such as x/D_h≥40. Turbulence intensity increases as the dimensionless transverse position increases from the center to the wall of the duct, and is slightly smaller in the accelerating phase than in the decelerating phase for the developing turbulent oscillatory flows. The entrance length of the turbulent oscillatory flow is about 40 times as large as the hydraulic diameter in the present experimental conditions.

원관내 비정상 유량계측에 관한 연구

박선종,박길문,강형선 조선대학교 생산기술연구소 1996 生産技術硏究 Vol.18 No.1

A new instantaneous unsteady flowmeter for hydraulic pipelines using cy lindrical chokes is studied experimentally. The instantaneous flowmeter is predicted in real time from measurement of pressure difference on both sides of cylinderical choke through the numerical operation of the transfer function between flowmeter and pressure drop. The sampling frequency can be set at 50Hz and 30Hz to maintain high response employing exclusive parallel operating circuits for multiplications and sums. Under unsteady laminar flow condition. the estimated flow rate waveforms are in good agreement with those measured by CCFM. Particularly. the dynamic response accuracy of the extrapolation method are experimentally investigaated in detail.

곡관 덕트내 난류 비정상유동의 압력분포

박길문,이행남,백대우,손현철 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1

In this study, Flow characteristics of turbulent unsteady flows in a square-sectional 180°curved duct were experimentally investigated. Experimental studies for air flow were conducted to measure pressure distributions in the square-sectional 180°curved duct by using a magnehelic differential pressure gage. The experiment were conducted in nineteen sections from the inlet (ø=0°) to the outlet(ø=180°) of the duct at 10°intervals. The results obtained from the experimentation are summarized as follows. (1) In the turbulent oscillatory flow, the pressure distribution was the largest in the accelerating and decelerating region of the bend angle of 90°and the pressure difference of the inner and outer walls was the largest before and after the bend angle of 90°. (2) In the turbulent pulsating flow, the pressure difference was the largest near the region of bend angle of 90°in the case of the middle region, and since then the pressure difference of the inner and outer walls became smaller.

통신사업자의 멀티미디어 사업영역 설정에 관한 연구

윤문길,박계두 한국항공대학교 경영연구소 1997 경영연구 Vol.4 No.1

The businesses of computing, communications, and content are converging or collapsing to create a new industry sector: multimedia industry. This new industry is the engine of the new economy and will be critical to leading a successful transition Synergy in the fields of telecommunication, information technology, consumer electronics and content providers is me of the key factor in making multimedia services and products a reality today. The convergence of these traditionally independent sectors is giving a great improvement to the multimedia market, providing the end users with new tools and services, almost unrealizable only a few yews aga In this paper, at a point of telecommunication carriers view, we address a business domain for multimedia market, which contains the scope of the multimedia business to be adopted and the integration strategy of the related business Based on the analysis for each multimedia industry, we recommend some suggestion for deciding the multimedia business domain of telecommunication carriers.

안전관리와 안전사고 모형에 관한 연구

오재화,박영길,김문채 朝鮮大學校 建設技術硏究所 2002 建設技術硏究 Vol.22 No.1

Bigger in the size, more diverse in the style, recently, the interest and necessity of effective safety consciousness during construction has been increased in the construction field. Through the literature reviews and questionnaire survey, this study proposes a realities of the effective safety consciousness in the construction field. The cause of safety supervision which influence safety prevention are diverse, among them, especially, the safety consciousness have great impact on the safety accident. According to, safety accidents can be protected through safety education and safety awareness of each employee. Ultimately, prevention and recognition against safety accident are changed depending on employed category of construction field, it is necessary to educate and confidence considering each employed category of construction work for safety supervision rather than to uniform education about safety consciousness.

油壓曲管路에서 非定常流의 壓力降下에 관한 硏究

李茂錫,朴吉文,曺秉崎 조선대학교 생산기술연구소 1984 生産技術硏究 Vol.6 No.2

The pressure props of coiled tubes were studied experimentally with hydraulic oil Gulf Harmony 32 for unsteady flows. In addition, friction factors are investigated as function of Curvature ratio(a/R), Reynolds number (Re), Dean number(De), and frequency parameter(α). The three coils were used with curvature ratio (a/R) of O.1, O.04, and O.02, and the total length of coiled tube is 11.3m, respectively. The experimental results are obtained as follows; 1). Pressure drops of straight tubes agree with Hagen-Poiseuille fomula. 2). Ratio of friction factors (fc/fs) is more than 1, and increases with Reynolds number. 3). Friction factor increases as curvature ratio (a/R) and number of coil are higher. 4). The ratio of friction factor (fc/fs) is higher when frequency parameter is of about 2∼3.

자동차용 시로코팬의 유동특성에 관한 연구

이행남,박길문,이덕구,정한별,김건일,설재림 朝鮮大學校 機械技術硏究所 2005 機械技術硏究 Vol.8 No.1

The sirocco fan is used to get low noise, and it has been applied to a lot of industry field like the heat engine, the fluid instrument power plant, the food industry, environment industry etc... because there are not problems even it is mixed with a any kind of liquid, gas, and solid. The flow characteristics in sirocco fan are investigated by PIV. The experiment using PIV measurement for Test section's flow characteristics acquired velocity distribution, Condition : when sirocco fan in automobile air controller maximum 1450RPM, and a revolution is a variation (l)950RPM, (2)l100RPM, (3) 1250RPM. The agreement a experiment shows the validity of this study and the results of this study would be useful to the engineers who design for the flow systems