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장창수,김종영,김영준,Jang, Chang-Su,Kim, Jong-Yeong,Kim, Yeong-Jun 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.5
Heat transfer in linear motor driven stages for surface mounting device applications was investigated. A simple one-dimensional thermal resistance model (TRM) was introduced. In order to reduce three-dimensional nature to one-dimensional, a few assumptions and simplifications were employed suitably. A good agreement with a finite element heat transfer analysis in temperature profile was obtained. For validation, the analysis was compared with the measurement with respect to motor driving power. Overall discrepancy was less than 7$^{\circ}C$. The influence of two high thermal resistance parts, insulation sheet and thermal contact between the coil assembly and the mounting plate, was examined through the analysis. Additionally, the thermal resistance analysis was applied to another stage including an internal cooling-air passage, and was found available for this system as well. After validation, the cooling effect was surveyed in terms of motor power, and cooling-air and -water flow rate.
와이어 본더용 Horn-Holder Assembly의 접촉 해석
장창수,안근식,김영준,곽동옥,부성운,Jang, Chang-Soo,Ahn, Geun-Sik,Kim, Young-Joon,Kwak, Dong-Ok,Boo, Seong-Woon 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.10
Joint structure of a transducer horn-holder assembly fur a wire bonder was examined through FEM contact analysis. A three dimensional modeling and analysis was carried out to survey the internal physics of this structure and to prove the accuracy of a computation compared to a measurement. After validation, a simple two dimensional model was built fur various parametric study considering the efficiency and speed of the computation. Several factors such as boundary conditions, a modeling boundary, mesh density and so on, were considered to obtain consistency with three dimensional analysis. An arc angle and a position of each holder boss were chosen as design parameters. A design of experiment was applied to find out an optimized design of the holder geometry. As a result, a guideline for holder boss design was suggested and main factors and their influence on stress concentration in the transducer horn were surveyed.
[가솔린엔진] 고압 선회분사기 노즐의 성능-전산유체 해석
장창수(C.S. Jang),배충식(C.S. Bae),최상민(S.M. Choi) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
A computational fluid dynamic tool was used to predict the performance of a prototype high-pressure swirl injector nozzle with respect to design parameters. Performance of the' prototype nozzle was investigated in terms of the flow rate and the initial spray angle. Design parameters included needle lift. needle-seat angles. orifice diameter and length. and needle-seat contact diameter. The most important parameter was found to be the orifice diameter. Transient flow rate was also examined. The needle-opening time was found to have influence on the linearity of the dynamic flow rate
4행정 직접분사식 성충화 엔진용 2유체 분사기의 운전조건에 대한 성능연구
장창수(C. S. Jang),김승수(S. S. Kim) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_1
The spray characteristics of a 2-phase injector intended to be installed on a direct-injection stratified-charge engine were studied using TV imaging system. The measured SMD of the spray was found to be around 15μm under various operating conditions. The higher the air supply pressure, air-liquid ratio, and ambient air density, the more finely atomized sprays were obtained from the injector. Experimental correlations obtained for the spray tip penetration and droplet SMD exhibited very similar tendencies to those from diesel injectors. Log-Bolzman function was turned out to be the best fitting one for the drop-size distribution. The secondary poppet bouncing, an unwanted characteristics observable from the current 2-phase injector and, yet, controllable with the adjustment of the spring constant, was shown to give a seriously detrimental effect on spray atomization.<br/>
4행정 직접분사식 성층화 엔진용 2유체 분사기의 운전조건에 대한 성능연구(Ⅱ)
장창수(C.S.Jang),김승수(S.S.Kim) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_2
The spray characteristics of a 2-phase injector for a 4-stroke DISC engine were studied following the previous study under identical title. While the previous experiments emphasized the macroscopic performances of the developed injector, microscopic view was concentrated on in the present paper to obtain more helpful basic data for the application to a real engine. The overall shapes of sprays from the 2-phase injector were captured using a TV imaging system. They included those informations on SMD of fuel droplets and fuel mass distributions at the end of an injection. The variances of the spray characteristics to the measuring positions and times were also investigated. As a result there were observations made on the effects of instantaneous ALR on the overall ALR. Two types of poppet bouncing, i.e., cyclic and secondary bouncing, were examined. While the former exhibited a beneficial effect on the atomization, the latter displayed a detrimental influence.<br/>
장창수(C.S.Jang),김승수(S.S.Kim),최상민(S.M.Choi) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_1
Correlations for predicting Sauter mean diameter(D32) with respect to operating conditions were obtained by energy considerations in intermittent air-assisted fuel atomization. It represents how each operating parameters such as injection pressure, ambient pressure, air-liquid mass ratio, and injected fuel mass influence atomization quality. A sphere model was introduced to illustrate the initial state of liquid fuel. When modified term including ALR, which had been obtained from an empirical equation of the previous study, was adopted to the original equation instead of ALR, the correlation predicted D32 more exactly. The current correlation exhibited favorable predictions of SMD compared to the prediction by empirical correlations at selected experimental conditions.<br/>
[가솔린엔진부문] 전산유체역학의 고압선회식 분사기 노즐부 내부유동해석 및 노즐설계에의 적용
장창수(Changsoo Jang),최상민(Sangmin Choi) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Although it has many limitation and defects of its own, a CFD approach is an effective way for investigation and prediction of fluid flow, especially for small injector nozzle flow owing to complexities and difficulties of the test nozzle fabrication process and flow measurements. In this study the internal flow of a high pressure swirl injector nozzle was investigated using a CFD tool. The formation of an initial solid jet spray and the irregular pattern at early period of a spray were explained through the interpretation of transient calculations. A method of manipulating the orifice geometry was proposed for enhancing the spray cone angle of the HPSI without swirl momentum control. A diverging orifice and a smaller orifice diameter plate were found to be the effective ones for this purpose. As an example of practical applications, cause identification of spray defects was presented. The results showed that the internal flow calculation could be utilized in nozzle and spray pattern design.
장창수(C.S.Jang),우동기(D.G.Woo),최상민(S.M.Choi) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.11_1
To use in GDI(Gasoline Direct Injection) engine. all parts of HPSI(High Pressure Swirl Injector) are designed and made. This Injector can be operated at 5.0MPa condition. Three types of swirl nozzle is built and tested. Ball type valve has better characteristics then conventional type. High pressure pumping system is constructed. Static and dynamic flow rate and spray angle of HPSI are mearured. Understanding of construction processes and major design factors in HPSI is acquired in this study.<br/>
대학병원 응급실로 내원한 치과 응급환자에 관한 임상적 연구
장창수(Chang-Su Jang),이창연(Chang-Yeon Lee),김주원(Ju-Won Kim),임진혁(Jin-Hyuk Yim),김좌영(Jwa-Young Kim),김영희(Young-Hee Kim),양병은(Byoung-Eun Yang) 대한구강악안면외과학회 2011 대한구강악안면외과학회지 Vol.37 No.6
Introduction: In today’s society, the rapid and appropriate care of the dental emergency patients is much more important. So, a retrospective study on the characteristics of emergency dental injuries and diseases will be very meaningful. Materials and Methods: This retrospective clinical study was carried by reviewing the radiographic films and emergency chart of 11,493 patients who had visited the emergency room of Hallym Sacred heart Hospital and were treated in the Department of Oral and Maxillofacial Surgery from January 2006 to December 2010. Results: The male to female ratio was 1.9:1. The highest monthly incidence was observed in May (10.4%) and June (8.9%) and the peak age distribution was the first decade (56.0%), followed by the second decade (16.0%). Trauma was the most common cause in dental emergency patients, followed in order by toothache, odontogenic infection, temporomandibular joint (TMJ) disorder and oral hemorrhage. Soft tissue injury was most prevalent in the trauma group, followed by tooth injury and facial bone fractures. In the tooth injury group, tooth fracture (56.7%) showed the highest incidence followed in order by tooth subluxation (18.2%), tooth concussion (16.9%), tooth avulsion (11.5%) and alveolar bone fractures (3.7%). In the facial bone fracture group, mandibular fractures (81.8%) showed the highest incidence followed in order by maxilla fractures (15.7%), nasal bone fractures (9.0%), zygomaticomaxillary complex fractures (5.4%), orbital bone fractures (2.5%). In mandibular bone fractures, the most common location was the symphysis (70.1%), followed in order by the mandibular angle (33.0%), mandibular condyle (22.8%) and mandibular body (13.6%). In the infection group, a submandibular space abscess (46.2%) was most common followed in order by a buccal space abscess (17.4%), canine space abscess (16.9%) and submental space abscess (12.3%). TMJ dislocation (89.3%) showed the highest incidence in the TMJ disorder group, followed by TMJ derangement (10.7%). In the other group, a range of specific symptoms due to post operation complications, trigeminal neuralgia, chemical burns and foreign body aspiration were reported. Conclusion: For the rapid and appropriate care of the dental emergency patients, well-organized system should be presented in oral and maxillofacial surgery. And it is possible under analysis of pattern and the variation of the dental emergency patients.