http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : 황중기(Joong-Ki Hwang) (검색결과 22 건)
- 무료
- 기관 내 무료
- 유료
-
-
-
-
-
골격성 제III급 부정교합 환자에 대한 상악골 전방견인 장치의 치료효과
황충주,경승현,임중기,Hwang, Chung-Ju,Kyung, Seung-Hyun,Lim, Joong-Ki 대한치과교정학회 1994 대한치과교정학회지 Vol.24 No.4
Before 1970, mandibular overgrowth was known as main cause of skeletal Class III malocclusion in growing children ; however, recent study reports that many skeletal Class III malocclusion patients also show maxillary deficiency. Since 1972, when Delaire re-accommodated Protraction Head Gear (P.H.G.), many researchers have reported that skeletal Class III discrepancies could be corrected through use of P.H.G., which induces anterior movement of maxilla and change in mandibular growth pattern into infero-posterior direction ; nevertheless, it is very difficult to predict resultant changes of orofacial region. The purpose of this study was to find out what treatment effect P.H.G. has on different study samples. Author divided 51 skeletal Class III malocclusion patients with maxillary deficiency who were treated with P.H.G. into different study groups depending on sex, treatment beginning age, intraoral appliance, and facial growth pattern. By doing so, following results were obtained. 1. Treatment beginning age and Sex Four age groups (5.8 to 8 year-old, 8 to 10 year-old, 10 to 12 year-old, 12 to 14 year-old) were compared, and no significant difference was observed. (p<0.05) There was no significant difference between the sex groups, either. (p<0.05). 2. Intraoral appliance Treatment effects of study groups that used R.P.E.(mean age of 10.2) and Labio-Lingual appliance(mean age of 8.9) were compared. There was no significant difference depending on the type of intraoral appliance that was used. (p<0.05) 3. Facial growth pattern 1) Amounts of SNB and ANB corrections were smaller in clockwise growth pattern group than those in normal or counterclockwise growth pattern group. (p<0.05) 2) Amounts of increase in Wits appraisal and mandibular plane angle were greater in counterclockwise growth pattern group than those in normal or clockwise growth pattern group. (p<0.05) 3)Amounts of increase in articular angle were greater in counter lockwise growth pattern group than those in clockwise growth pattern group. (p<0.05)
-
Joong-Ki HWANG(황중기),Min-Soo SUH(서민수) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.06
Heat pipe generally transfer thermal energy from one regime to another essentially evaporator to condenser. Superalloy envelope with alkali-metal (sodium, potassium) working fluid for high temperature heat pipe (HP). Na-AMTEC convert between thermal energy and electrical energy, in specific terms, the static energy conversion subjected to electrochemical reaction mainly depending on its chemical kinetics and temperature. In particular, Na-AMTEC convert energy between heat and electricity transpired via ionization of natrium as known as reduction and oxidation (REDOX) which is differentiate it from the dynamic energy conversion. In specific terms, 1) the input of thermal energy is converted into electrical energy as same as a thermoelectric cell, 2) the input of thermal energy is converted into the sum of electrical energy P<sub>e</sub> and thermal energy P<sub>th</sub>, as same as a combined heat & power (CHP) and 3) the input of electrical energy is converted into thermal energy as same as an electrochemical heat pump. Na-AMTEC could highly utilized in aforementioned objectives with efficiencies potentially near Carnot theorem. In case of thermal energy in both of Na HP and Na-AMTEC, the alkali-metal is an energy medium of heat transfer (HF) and heat transfer fluid (HTF). The purpose of Na HP is transferring thermal energy from source to sink with maximizing heat transfer rate and minimizing the heat loss to ambient surroundings. Similarly, the purpose of Na-AMTEC, alkali-metal based thermopower HP, is to convert thermal source into electricity in order to reduce several conventional stages of conversion processes e.g. thermal energy loss during phase change of HTF, energy loss in terms of temperature and pressure during the energy transportation and energy loss during relative mechanical motion results from energy loss and materials squander due mainly to friction and wear. This study is to report the development efforts of Na HP and thermopower HP fabricated for high grade to low grade temperature power generation.
-
황중기(Joong-Ki Hwang) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
자동차 연비 향상을 위해 고강도 선재제품에 대한 요구가 지속적으로 있어 왔으나, 기존의 선재제품 사용 소재는 높은 수소취성파괴 민감도로 인해 더 이상 제품의 고강도화 어려운 상황이다. 또한 이들 소재들은 낮은 가공성으로 인해 제품 생산을 위해 다양한 열처리가 필요하여, 제품 원가가 높고, 환경 파괴의 원인이 되는 오염물질을 발생시킨다. 상기 문제점을 해결하기 위해 Hwang [1] 은 고강도, 고연성, 낮은 수소취성파괴 민감도를 나타내는 Twinning-induced plasticity (TWIP) steel을 선재제품에 사용할 것을 제안했다. TWIP 강은 가공중 발생하는 기계적 쌍정에 의해 높은 가공성과 가공경화지수를 나타내게 된다 [2]. 이러한 TWIP 강의 높은 가공성은 선재제품 생산시 필요한 annealing 열처리를 생략하게 하고, 높은 가공경화지수는 quenching/tempering 열처리를 생략할 수 있게 한다. Recently, improving the fuel efficiency and safety standards is one of the major issues in the wire rod industry for automotive applications to save the energy and environment. Therefore, there is a great need for the development of new materials having high strength without the degradation of other properties, such as ductility, toughness, and resistance to hydrogen-delayed fracture (HDF). Hwang [1] reported that one of the candidates meeting such property requirements is the twinning-induced plasticity (TWIP) steels having combination of high tensile strength and extraordinary ductility [2]. They recommended that TWIP steels have many advantages in comparison with the ferritic, pearlitic and tempered martensitic steels that are commercially used for wire rod products and can be the suitable material for high strength wire rod products: higher strength, outstanding ductility, better HDF resistance, and elimination of post heat treatments.
-
황중기(Joong-Ki Hwang) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
The effect of drawing speed on temperature rise and microstructure distribution in twinning-induced plasticity (TWIP) steel during wire drawing has been investigated to improve drawability for wire rod applications. Although wire drawing process is performed at room temperature, heat is generated due to the plastic deformation and friction at the wire-die interface. The steel wires subjected to the low drawing speed (LD) of 0.5 m/min and the high drawing speed (HD) of 5.0 m/min were analyzed using the numerical simulation and electron backscatter diffraction (EBSD) techniques. Interestingly, the specimens subjected to the HD had a higher drawability by about 18% compared to the LD, which is totally different from the general behavior of plain carbon pearlitic steels. The LD wire had uniform temperature distribution along the radial direction during wire drawing. In contrast, the HD wire had a temperature gradient along the radial direction due to the higher frictional effect at surface: the minimum temperature of 58℃ at center area and the maximum temperature of 143℃ at surface area. The higher stacking fault energy (SFE) of HD wire at the surface area due to the high temperature rise retarded twinning rate, resulting in the prevention of fast exhaustion in ductility in comparison with the LD wires since the earlier depletion of twins at surface area is known as the main reason for the fracture of TWIP steel during wire drawing. Consequently, HD process delayed the fracture strain of wire and increased the uniformity of microstructure and mechanical properties along the radial direction.
-
황중기(Joong-Ki Hwang),손일헌(Il-Heon Son),이덕락(Duk-Lak Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
A coupled thermal and metallurgical mathematical model and off-line simulator have been developed to simulate the Stelmor process for controlled cooling of steel wire rod. In order to solve one-dimensional transient heat transfer equation including the heat evolved from phase transformation, a finite difference method coupled with thermodynamic and kinetic analysis was employed. This model takes into account the temperature-dependent heat transfer and thermophysical properties and stresses the importance of the enthalpy of transformation. A developed model and off-line simulator have been shown to simulate the complex heat flow in the Stelmor process excellently and calculated results were in good agreement with measured temperature.
-
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
