• 한국자동차공학회논문집
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• 제7권8호
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• pp.17-23
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• 1999

This paper presents the characteristics of the gas flow in the engine cylinder under various intake flow conditins. The particle tracking velovimetry(PTV) was used to anlayze the gas flow pattern and flow field in the cylinder. Effects of tumble intensifying valve(TIV), swirl intensifying valve(SIV) and one-valve deactivated condition on in-cylinder flow patterns were compared with the baseline engine udner 600rpm motoring condition. In addtion, tumbel ration was estimated rwith results of in -cylinder flow fields. Base on experimental results, the tumble ration of in-cylinder flow field has the maximum value at the bottom dead center for the different four inlet conditions. In TIV condition, the tumble ration is 1.35 times larger than that of baseline engine and 1 intake valve deactivated condition is effective to improve in-cylinder swirl motion.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.265-270
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• 1999

At this study, we investigated the chemical component and the mineral granular composition of sedimentary rock and others where were distributed in Taegu area and compared correlations with each data through the various physicla and mechanical characteristic test. As the result, d and E, they are kinds of granite, which contain much albite than others were proved to be strong by mechanical tests and the correlation moduli were proved to be more than 0.8 except P wave velocity-Poisson's ration relation when examined Elastic moduluous -Poisson's ration, P, wave velocity-Uniaxial compression strength, Elastic modulous -Uniaxial compression strength and Uniaxial compression strength-Poisson's ration correlation function graph.

• 한국진공학회지
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• 제7권s1호
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• pp.30-36
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• 1998

The plasma-spray technique is currently the most frequently used method to produce calcium phosphate coatings. Hydroxyapatite(HAp), one form of calcium phosphate, is preferred by its ability to form a direct bond with living bone, resulting in improvements of implant fixation and faster bone healing. Recently, concerns have been raised regarding the viable use and long-term stability of plasma-spray HAp coatings due to its nature of comparatively thick, porous, and poor bonding strength to metal implants. Thin layers (maximum of few microns) of calcium phosphate were formed by an e-beam evaporation with and without ion bombardments. The Ca/P ration of film was controlled by either using the evaporants having the different ration of Ca/P with addition of CaO, or adjusting the ion beam assist current. The Ca/P ration had great effects on the structure formation after heat treatment and the dissolution bahavior. The calcium phosphate films produced by IBAD exhibited high adhesion strength.

• 한국임상수의학회지
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• 제15권1호
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• pp.62-74
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• 1998

In feedlot cattle the abrupt change of diet from roughage to a large quantity of grain for the purpose to improve production often results in increased occurrence of rumen acidosis or acute carbohydrate encouragement enterotoxemia, bloats diarrhea liver abscess and laminitis or robot disease. The common management practice to control these problem is to increase the amount of concentrates in the diet in a stepwise manner until the animals are adapted to a high-grain ration. However this practice requires at least about 3 weeks adaptation period and specially prepared adaptation rations which contain various amount of concentrates. Present experiment was undertaken in order to findout the more simple and rapid adaptation method of cattle to a high grain ration. Nineteen Korean calves aging from four to six month were fed artifical hay (Youngchoun Chuk-Hyup, Korea) which contains 10% of concentrates or alfalfa and rye grass hays for two months and randomly alloted to three experimental groups and two control groups. The experimental group-1 was inoculated by stomach tube for two days with li500 ml/day of ruminal fluid fished from Korean beef cattle that had been previously adapted to a high-energy ration. The experimental group-2 was inoculated by trocalization for two days with the same ruminal fluid. The experimental group-3 was inoculated by trocalization with 1,500 ml/day of bacterial culture which contained 2$\times $10$^{9}$/m1 of Gram-negative bacteria derived from adapted luminal fluid. The two control groups were treated with normal saline solution by the same methods. All animals were fed high-energy ration that contained 80% of grain ad libitum for 30-74 days beginning on the third of the treatment. The effect of the inoculation on the adaptation was observed clinicopathologically with the following results; All of the experimental calves inoculated with the ruminal fluid or Gram-negative bacterial culture derived from adapted cattle did not show any signs of rumen acidosis or other related diseases, while most of the control calves did show diarrhea and bloat and a calf laminitis. The average daily weight gain and feed efficiency of experimental calves were slightly improved compared with control calves. Following the feeding of high-grain rational the pH of the ruminal fluid was lowered in both the experimental and control groups. However severe acidosis with the pH of below 5.0 was observed in only a control group-2. The protozoal number in ruminal fluid was markedly decreased during the high-grain feeding in both the experimental and control calves. However the decrease was mere severe in control calves compared with the experimental calves. The activation of the protozoa were completely disappeared within nine hours at the refrigerator temperature (4"C). No significant differences in heamatological and blood chemical values between the experimental and control calves were recognized. However in one control calf which showed clinically laminitis marked elevations of serum glutamic oxaloacetate transaminase and lactic dehydrogenase activities and a decrease of serum glucose level were observed. From these results it would be concluded the intraruminal transplantation of unadapted calves with the adapted ruminal fluid from cattle previously adapted to a high-energy ration prevents disease problem associated with high-grain feeding and improve weight gain and feed efficiency.ency.

• 한국방사선학회논문지
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• 제15권2호
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• pp.117-123
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• 2021

본 논문에서는 흉부 저선량 CT와 복부 비조영 CT에서 선량기록을 바탕으로 환자선량에 영향을 줄 수 있는 요인과 상관관계를 확인하여 실질적인 선량 감소 방안의 근거를 마련하고자 하였다. 흉부 저선량 CT와 복부 비조영 CT 검사 시 불필요하게 피폭이 발생하는 원인을 찾기 위해 7가지 요인(나이, 성별, 키, 몸무게, BMI, 환자 상태 (입원, 외래), dose modulation 활성화 유무)과 CT 선량과의 상관관계를 확인하였다. 상관관계 확인을 위해 사용된 통계기법으로는 로지스틱 회귀분석을 사용하였다. 흉부 저선량 CT 검사에서는 키가 클수록, BMI 가 높을수록, dose modulation을 비활성화한 경우에 진단참고수준 (diagnostic reference levels, DRL) 기준치의 초과 위험률이 낮아졌다 (odds ration<1; p<0.05). 또한 여성의 경우와 몸무게가 클수록 DRL 기준치의 초과 위험률이 높아졌다 (odds ration>1; p<0.05). 복부 비조영 CT 검사에서는 몸무게가 클수록, dose modulation을 비활성화한 경우에 DRL 기준치의 초과 위험률이 낮아졌다 (odds ration<1; p<0.05). 이처럼 방사선 피폭에 영향을 주는 다양한 요인에 대한 연구를 수행하여 환자 선량과의 연관성을 찾고 이에 따른 선량을 낮추는 노력이 필요할 것으로 사료된다.

• 한국가금학회지
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• 제15권4호
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• pp.269-275
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• 1988

단백질 수준이 18%인 초생추 사료와 12%인 비육우 후반기 사료를 입자도의 크기에 따라 전 사료의 80%가 1.19mm 이하인 것과 전 사료의 40%가 1.19mm 이하인 것으로 나누어서 40일간 저장후 각 처리구의 영양소 변화를 비교하였다. 영양소 변화를 비교한 후 초생추 사료만을 이용하여 입자의 크기를 다르게 하여 항곰팡이제를 처리한 사료와 처리하지 않은 사료에 대한 병아리의 성장 및 사료이용 정도 그리고 장기의 발달을 비교하였다. 항곰팡이가 처리되지 않은 사료에서는 2개의 다른 단백질 수준에서 공히 지방과 카로틴 함량은 현저히(P＜0.05) 감소를 초래하였다. 항곰팡이제가 처리된 사료에서도 입자 크기가 1.1mm 보다 작은 것이 전체 사료의 40% 이하인 구에서는 지방과 카로틴의 함량이 40일간의 저장 후 에는 감소하는 추세를 보였다. 또 입자가 큰 사료에서 항곰팡이제를 처리하지 않았을 때는 신선한 사료나 항곰팡이제를 처리한 구에 비교하여 병아리의 성장이나 사료 섭취량은 현저히 감소(P＜0.05)를 나타냈다. 사료효율 역시 항곰팡이제를 처리하지 않은 구에서 현저히 맞았다. (P＜0.05), 그러나 각 장기의 무게에는 처리간에 차이를 나타내지 못하였다.

• 한국가금학회지
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• 제15권4호
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• pp.261-268
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• 1988

단백질 수준이 각각 18%(초생추 사료)와 12% (비육우 사료)인 사판 사료를 사료 입자 크기로 나누어서 1.1mm이하가 전사료에 대한양외 80%와 40%인 것으로 만든 다음 각각 다른 단백질 수준과 입자 크기가 배합 사료내에 함유된 항곰광이제(0.1% W/W)의 효능에 어떻게 영향을 미치는지에 관하여 연구하였다. 시험 사료내에 함유된 수분의 함량은 12.6% (초생추 사료)와 12.7%(비육우 사료)였다. 시험 사료를 각 처리 별로 1kg씩 나누어 플라스틱통에 넣은 후 뚜껑을 약간 열어둔 상태로 상대습도가 85% 저장 온도를 $29{\pm}$$1^{\circ}C$ 되게 유지시킨 채 5일에서 40일 동안 보전한 후 곰팡이수, 생성된 탄산 가스양 그리고 생성된 아플라 톡신의 양을 측정하였다. 형성된 곰팡이 수(P＜0.05)와 탄산가스 발생양(P＜0.01)은 항곰팡이제가 가해졌을 때 사료의 입자 크기가 1.1mm이하인 것이 전사료의 40%인 구에서 현저히 높았으나 단백질 수준의 차이는 항곰팡이제의 작용에 영향을 미치지 못했다. 그러나 아플라 톡신의 생성은 사료중의 단백질 수준이 높을 수록 많았고(P＜0.05) 또 입자가 큰 것이 많은 사료일수록 현저히 높았다(P＜0.05).

• The Journal of the Acoustical Society of Korea
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• 제17권4E호
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• pp.41-47
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• 1998

Microphone is the first link in the speech recognition system. Depending on its type and mounting position, the microphone can significantly distort the spectrum and affect the performance of the speech recognition system. In this paper, characteristics of the speech signal for different microphones and microphone distances are investigated both in time and frequency domains. In the time domain analysis, the average signal-to-noise ration is measure ration is measured for the database we collected depending on the microphones and microphone distances. Mel-frequency spectral coefficients and mel-frequency cepstrum are computed to examine the spectral characteristics. Analysis results are discussed with our findings, and the result of recognition experiments is given.

• 한국농공학회지
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• 제41권3호
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• pp.73-80
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• 1999

The objective of this study were to investigate the properties and to improve the disadvantages of the polymer concrete such as brittle fracture, large hardening shrinkage . In this paper, steel fiber reinforced polymer concrete is prepared with various steel fiber aspect ratios(ι/d), contents(vol.%), and their material characteristics were investigated experimentally . The aspect ration (ι/d) of the steel fiber was reversly proportional to slump value, and slump value tended to decrease as increase of steel fiber content . And harding shrinkage and impact resistance tended to be improved as the steel fiber content and aspect ration were increased.

• 대한가정학회지
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• 제5권1호
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• pp.794-814
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• 1966