• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제14권4호
• /
• pp.275-282
• /
• 1992

Maxillofacial war injures is specific representative of severe hard and soft tissue defect. This type of injuries were different from the trauma because it may be fatal. The purpose of this study was to evaluate the injury type base on the retrograde medical record in the 104 patients from Feb. 1991 to Aug. 1992 in Korea Veterans Hospital. The obtained results were as follows. 1. Among 104 cases, 51 cases(49.0%) were classified as mandibular defects only, and 53 cases (51.0%) were classified as maxillary with mandibular defect (combined). 2. The etiologic factors of injury were gunshot, artillery and grenade or shell: 33 cases, 14cases, and 10 cases respectively in Korea War, 19 cases, 5 cases, and 8 cases respectively in Vietnam War. 3. In 57 cases of mandibular partial defect, the angle area showed the highest frequencies, 18 cases(31.6%). 4. In 42 cases of mandibular segmental defect, the area between the 1st molar and the ascending ramus showed the highest frequencies. 17 cases(40.4%), and almost all cases were unilateral defect (40 cases, 95.0%) 5. Reconstruction method performed for segmental mandibular defect were wire or plate(15 cases, 35.7%) and soft tissue closure only(12 cases, 28.7%), respectively.

• 한국분말재료학회지
• /
• 제17권4호
• /
• pp.302-311
• /
• 2010

In this research, the refinement behavior of the coarse magnesium powders fabricated by gas atomization was investigated as a function of milling time using a short duration high-energy ball milling equipment, which produces fine powders by means of an ultra high-energy within a short duration. The microstructure, hardness, and formability of the powders were investigated as a function of milling time using X-ray diffraction, scanning electron microscopy, Vickers micro-hardness tester and magnetic pulsed compaction. The particle morphology of Mg powders changed from spherical particles of feed metals to irregular oval particles, then platetype particles, with increasing milling time. Due to having HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, resulting in producing plate-type powders. With increasing milling time, the particle size increased until 5 minutes, then decreased gradually reaching a uniform size of about 50 micrometer after 20 minutes. The relative density of the initial power was 98% before milling, and mechanically milled powder was 92~94% with increase milling time (1~5 min) then it increased to 99% after milling for 20 minutes because of the change in particle shapes.

• 동력기계공학회지
• /
• 제16권4호
• /
• pp.30-36
• /
• 2012

A scroll expander has been designed to produce a shaft power from a R134a Rankine cycle for electricity generation. Heat was supplied to the Rankine cycle through a heat exchanger, which received heat from another cycle of water. In the water cycle, water was heated up in a boiler using biogenic solid fuel. The designed scroll expander was a horizontal type, and a trochoidal oil pump was employed for oil supply to bearings and Oldham-ring keys. For axial compliance, a back pressure chamber was created on the backside of the orbiting scroll base plate. Numerical study has been carried out to estimate the performance of the designed scroll expander. The expander was estimated to produce the shaft power of about 2.9 kW from a heat supply of 36 kW, when the temperature of R134a was $80^{\circ}C$ and $35^{\circ}C$ at the evaporator and condenser of the Rankine cycle, respectively. The expander efficiency was about 70.5%. When the amount of heat supply varied in the ranges of 7.5~55 kW, the expander efficiency changed in the range of 45.6~70.5%, showing a peak efficiency of 70.5% at the design shaft speed.

• International Journal of Korean Welding Society
• /
• 제2권2호
• /
• pp.26-31
• /
• 2002

Considering the fuel consumption of car, a light structure of aluminum alloys is desired fer car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. In the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6NO 1 alloy welds. Aluminum alloy plate of 2.Omm in thickness with filler metal bar was welded by twin beam Nd: YAG laser facility (total power: 5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 1/min was used. The defocusing distance is kept at 0 mm. At travel speeds off 3 to 9 and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

• 한국농공학회지
• /
• 제16권2호
• /
• pp.3430-3437
• /
• 1974

.It is very importaut to know the water consumption of crops in planning irrigation works and practicing suitable soil moisture management. For the purpose of making it clear that how much water be consumed to cultivate the Chinese cabbage, Chamber method has been applied. Main equipments in the transpiration chamber are flowers, manometer and electric thermograph. The chamber made of vynyl plate has a small entrance at the base and an exit at the top, and the ventilation in the chamber was carried out by a flower through the entrance and exit. Air-flow adjusted by an orifice manometer enters the chamber from the outside over the crop canopy through the pipe like a chimney and finally goes out to the outside. Two sets which consist of a pair of dry and wet bulb made by thermistor are installed in the entrance and exit tube, and record air temperature automatically. Evapotranspiration amount is computed from the air-flow quantity and difference in absolute humidity between at the entrance and exit of the chamber by the following equation: ET=(X2-X1)${\times}$Q where ET=evapotranspiration amount X1=absolute humidity at the entrance(g/㎥) X2=absolute humidity at the exit(g/㎥) Q=air-flow quantity(㎥) This study was carried out at the upland farm of the Institute of Agriculture Engimeering and Utilization, Suwon, Korea. from 1971 to 1973. The results obtained in this experiment are as follows: 1. The total amount of evapotranspiration of Chinese Cabbage that is cultivated in autumn is 408.1mm during growth period. 2. Chinese cabbage rapidly grows up in the second ten days of September, 40th to 50th days after seeding. At the same time, the maximum amount of evaportranspiration of Chinese cabbage is 61.6mm/10 days 3. The correlation between Pan-evaporation and evapotranspiration is high, coefficient of correlation r=0.88**, and can be shown as The following regression equation: ET=0.913E+20.273 4. Evapotranspiration is closely related with meteorological factors: r=0.85**, for insolation, r=0.76** for air temperature, respectively. 5. The percentage of evapotranspiration amount, at the beginning of growth stage, gradually increases in proportion as the Chinese Cabbage grows but is largely affected by meteorological factors after the green cover formation. 6. By Blaney and Griddle formula, evaportranspiration coefficient "K" are within from 0,85 to 1.27.

• 대한미생물학회지
• /
• 제22권4호
• /
• pp.435-443
• /
• 1987

A total of 30 strains of Candida albicans were examined for susceptibility to amphotericin B and ketoconazole using Sabouraud's dextrose broth, Kimmig broth and Supplemented yeast nitrogen base broth media. Furthermore, the growth curve and colony forming units were checked for use of stationary-phase cells and 2-hour incubation cells in the absence of atifungal agents. The viable counts were determined periodically during incubation by standard plate count techniques. The minimum inhibitory concentrations of amphotericin B for use of stationary phase cells were as follows: SDB, $0.09{\sim}0.97mcg/ml$(0.39mcg/ml); Kimmig broth, $0.19{\sim}0.39mcg/ml$(0.42 mcg/ml) and SYNB, $0.19{\sim}0.39mcg/ml$mcg/ml(0.23mcg/ml). In ketoconazole, MICs were value SDB, $3.12{\sim}25.0mcg/ml$(12.5mcg/ml); Kimmig broth, $12.5{\sim}25.0mcg/ml$ (22.5mcg/ml) and SYNB, $3.12{\sim}12.5mcg/ml$(6.71mcg/ml). The MICs of amphotericin B(0.2mcg/ml cone.) for use of 2-hour incubation cells in absence of AMB were, SDB, $0.04{\sim}0.39mcg/ml$(0.11mcg/ml); Kimmig broth, $0.09{\sim}0.39mcg/ml$(0.18mcg/ml) and SYNB, $0.09{\sim}0.19mcg/ml$(0.14mcg/ml) and in KTZ, the value of MICs were SDB, $3.12{\sim}25.0mcg/ml$(12.22mcg/ml); Kimmig broth, $0.78{\sim}25.0mcg/ml$(11.01mcg/ml) and SYNB, $1.56{\sim}12.5mcg/ml$(3.90mcg/ml). The two-log reductions in CFU per milliliter observed when 2 hour preincubation cells were treated with 0.2mcg/concentrations of AMB and 25.0mcg/ml of KTZ. However, AMB treated cells were restored to growth activity, it suggested that the AMB has no active antifungal activity.

• 한국지반환경공학회 논문집
• /
• 제7권6호
• /
• pp.23-34
• /
• 2006

본 연구에서는 보강재의 침하를 허용하는 침하형 보강토 옹벽의 거동을 평가하기 위하여 원심모형실험을 수행하였다. 실험결과는 연결부의 침하를 허용하지 않는 일반형 보강토옹벽에 대한 결과와 비교 분석하여 침하형 보강토 옹벽의 안정성을 평가하였다. 모형실험에서 전면판은 알루미늄판을 사용하였으며, 보강재는 알루미늄 호일을 이용하였으며, 뒤채움지반은 화강풍화토를 사용하였다. 실험결과, 침하자유형 보강토옹벽은 80g의 중력수준에서 완전한 파괴상태에 도달하였으며, 일반형 보강토 옹벽이 69g의 중력수준에서 파괴된 것을 감안하면 침하자유형 보강토 옹벽이 안정성이 우수하다는 것을 확인할 수 있었다. 또한, 69g에서 침하자유형 보강토옹벽 저면에서의 수직토압이 일반형에 비해 16% 정도 크게 측정되었다.

• The Journal of Advanced Prosthodontics
• /
• 제6권3호
• /
• pp.207-214
• /
• 2014

PURPOSE. This study characterized the synthesis of a modified PMMA (Polymethyl methacrylate) denture acrylic loading platinum nanoparticles (PtN) and assessed its bacterial inhibitory efficacy to produce novel antimicrobial denture base material. MATERIALS AND METHODS. Polymerized PMMA denture acrylic disc ($20mm{\times}2mm$) specimens containing 0 (control), 10, 50, 100 and 200 mg/L of PtN were fabricated respectively. The obtained platinum-PMMA nanocomposite (PtNC) was characterized by TEM (transmission electron microscopy), SEM/EDX (scanning electron microscope/energy dispersive X-ray spectroscopy), thermogravimetric and atomic absorption spectrophotometer analysis. In antimicrobial assay, specimens were placed on the cell culture plate, and $100{\mu}L$ of microbial suspensions of S. mutans (Streptococcus mutans) and S. sobrinus (Streptococcus sobrinus) were inoculated then incubated at $37^{\circ}C$ for 24 hours. The bacterial attachment was tested by FACS (fluorescence-activated cell sorting) analysis after staining with fluorescent probe. RESULTS. PtN were successfully loaded and uniformly immobilized into PMMA denture acrylic with a proper thermal stability and similar surface morphology as compared to control. PtNC expressed significant bacterial anti-adherent effect rather than bactericidal effect above 50 mg/L PtN loaded when compared to pristine PMMA (P=.01) with no or extremely small amounts of Pt ion eluted. CONCLUSION. This is the first report on the synthesis and its antibacterial activity of Pt-PMMA nanocomposite. PMMA denture acrylic loading PtN could be a possible intrinsic antimicrobial denture material with proper mechanical characteristics, meeting those specified for denture bases. For clinical application, future studies including biocompatibility, color stability and warranting the long-term effect were still required.

• 한국패류학회지
• /
• 제5권1호
• /
• pp.1-9
• /
• 1989

A scanning electron microscopic study on the glochidium and glchidial encystment of Anodonta grandis on the guppy was conducted. The shape of the glochidium is apparently triangular and its averge size is 0.45mm X0.4mm when closed, The two glochidial shell valves are of the same size, kept together by a ligament of 120${\mu}{\textrm}{m}$ in length and 7 ${\mu}{\textrm}{m}$ in width. Each of the glochidial shell valves has a 16 ${\mu}{\textrm}{m}$ long hook sitdded with many spines on the superior face. A large area to the apex of the valve surrounding the base of the hook is provided with numerous small spines which become progressively smaller towards the periphery of the area, The external surface of the glochidial shell valve is covered with numerous small processes showing successive change in the shape and the pattern of destribution by part. Besides the processes, there are a number of niches scattered all over the exterior surface. The glochidial shell valve has two layers. One is the outer thin membrane bearing the processes and the niches and the others is the inner layer bearing numerous holes which any accessory structure and 2.65 ${\mu}{\textrm}{m}$ in diameter, emerges from a canal located at center of ventral plate of the mamtle, A total of three types of the hair cells are observed. In present artificial infection of the glochidium to the guppy, it took about three to four hours to complete an early cysts, During the period of encystment, The epithelial cells of the host fish actively migrated toward the attached glochidium and covered it.

• 대한조선학회논문집
• /
• 제29권1호
• /
• pp.1-13
• /
• 1992

본 논문은 선박의 초기설계와 중앙단면 설계용 지식베이스 시스템을 개발하고 지식공학이 선체구조 설계 분야에 매우 효율적으로 적용될 수 있음을 검토하는데 그 목적이 있다. 이를 위하여 첫째 구조설계에 적합한 지식베이스 전문가 시스템 개발용 도구(tool)인 E.1을 개발하였다. E.1은 C언어로 작성되었고 구조설계 과정을 효율적으로 뒷받침해주기 위해서 자동 반복 계산과 재추론 기능을 갖고 있다. 둘째 살물선의 초기설계시 주요치수 추정과 중앙단면 설계를 위한 지식베이스를 개발하였다. 이 지식베이스들은 통계적 경험식, 선급 규정, 경험적 지식 등을 rule, fact, table로 표현하여 구성하였다. 셋째 지식베이스의 추론을 통하여 중앙 단면 최적 설계 프로그램의 입력 자료를 생성하고 최적화 프로그램을 수행시키는 통합(hybrid) 시스템을 구축하였다. 넷째 보강판 설계용 지식베이스 시스템을 개발하기 위해 최적화 결과의 회귀분석을 이용하는 간이 설계법을 적용해 보았다. 이 시스템을 사용하여 살물선과 보강판의 설계과정을 보이고 그 결과를 검토해 보았다. 앞으로 E.I와 성능 개선과 더 우수한 지식베이스가 축적됨에 따라서 선체 구조설계에 사용되는 기존의 CAD 시스템의 성능이 크게 보완될 것으로 기대된다.