• 대한기계학회논문집
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• 제18권2호
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• pp.432-445
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• 1994

From a theoretical analysis point of view, the 2-stage precipitator is decomposed into two units: charging cell and collecting cell. Collection efficiency predictions of the two-stage parallel-plate electrostatic precipitator have been performed theoretically incorporating with the charging and the collecting cells. Particle trajectorise passing the charging cell have been modeled as a simple one. Particle charge distribution at the outlet of the charging cell is calculated through integration of the present unipolar combined charging rate along the entire particle trajectory, and average charge of particles at the outlet of the charging cell is obtained from the particle charge distribution. As for the collecting cell, the diminution of particle concentration along the longitudinal direction of the collecting cell is investigated considering the conventional Deutsch's theory and the laminar theory. One should note that the collection efficiency formula derived is based on monodisperse aerosols. It has been confirmed through the analysis that predictions of particle charge by applying White's unipolar diffusion charging theory overpredict actual cases in the continuum regime, while predictions by Fuch's unipolar diffusion charging theory indicate the reasonable result in the same regime. Theoretical predictions of collection efficiency are also compared with the available experimental results. Comparisons show that the experimental results are consistently located in the collection efficiency region bounded by the two limits, the Deutsch and the laminar collection efficiencies. Finally design parameters of the 2-stage electrostatic precipitator have been investigated systematically through the one-variable-at-a-time method in terms of collection efficiency. Applied voltages on the corona wire of the charging cell and the plate of the collecting cell, and the average air velocity have been selected as the design parameters.

• 대한예방한의학회지
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• 제9권1호
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• pp.49-63
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• 2005

Objectives : Ojayeonjonghwan(五子衍宗丸) is composed of Polygonum multiflorum THUNB, and some medical herbs that are known as formula of senescence delay effects. The purpose of this study is to investigate th effect of Ojayeonjonghwan on antioxidant enzyme activities, such as Thiobarbituric acid reactive substance(TBARS), Superoxide dismutase(SOD), Catalase(CAT), Glutathione preoxidase (GSH-px) in rat erythrocytes and blood plasma. Methods : Sprague-Dawley rats were divided into 3 groups, Normal group (supplied enough water and feeds only, Normal Group), D-galatose administered group(injected D-galatose 50mg/kg, 1time/day for 6 weeks, Control Group) and Ojayeonjonghwan administered group (D-galactose 50mg/kg and Ojayeonjonghwan extracts 245.0mg/200g 1time/day for 6 weeks, OJY Group). Rats were sacrificed and TBARS, SOD, CAT, GSH-px, Plasma total lipid, Plasma triglyceride and cholesterol were measured in rat erythrocytes and blood plasma. Results : TBARS in plasma concentration of OJY group was significantly lower than that of control group. Red blood cell(RBC) SOD activity of OJY group was significantly higher than that of control group(F=16.057, p=0.0001, ANOVA test), RBC GSH-px activity of OJY group was increased(F=4.271, p=0.034, ANOVA test). RBC catalase activities of all experimental group were not significantly different. Total lipid and triglyceride concentration in plasma of all experimental groups were not significantly different. Total cholesterol concentrations in plasma of OJY group were significantly lower than those of control group(F=4.387, p=0.032, ANOVA test). Conclusions : According to the above results, it is considered that Ojayeonjonghwan is effective in inhibiting lipid peroxidation and increasing antioxidative enzyme activities in D-galactose induced aging rat.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.134-141
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• 2005

Semi-Spherical Continuously Variable Transmission(SS-CVT) is the CVT which transmits power by rolling friction between dry metals, and its outstanding advantage is the ability of realizations of neutral, forward and reverse states without relying on any other devices. A spherical shaped variator transmits power and also changes gear ratio where keeping contact with a output disk. The frictional direction to transmit power and the other direction to change gear ratio are perpendicular to each other, so we can describe that two dimensional rolling friction is occurred in the contact point between the variator and the disk. Since magnitudes or relations of the two forces are completely unknown, they were analyzed by the experiments in this study. We determined the variables related with the friction phenomena by the dimensional analysis, and manufactured the SS-CVT test bench which could measure the related variables. Finally, the empirical formula for evaluating the two friction forces was proposed based on the experimental results.

• 대한한방부인과학회지
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• 제31권4호
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• pp.128-146
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• 2018

Objectives: This study was performed to analyze the prescriptions of Korean herbal medicine which had been commonly used during postpartum period. Methods: We searched literature on postpartum cares with Korean Herbal medicine in 4 domestic search engines. After that, we conducted eligibility screening based on inclusion and exclusion criteria. Results: 1. We selected total 48 studies. There were 40 clinical studies (25 case reports and 15 case series) and 8 animal experimental studies. 2. Of the 40 clinical studies, other treatments were used together with herbal medicine : acupuncture (28), chuna manipulation (3), and pharmacopuncture (5). 3. Of the 25 case reports, the most common symptoms were musculoskeletal symptoms (8), followed by mental disorders including postpartum depression (5). Various prescriptions of herbal medicine were used depending on the diseases or symptoms. 4. In 15 case series, 665 subjects in 11 case series had taken Saenghwa-tang-gagam within 1~2 weeks after childbirth, and the average duration of Saenghwa-tang-gagam administration were $9{\pm}4.97$ days. 498 subjects in 9 studies were breast-feeding, and there were no side effects reported. 5. All experimental studies were about the recovery, the immunity and the breast-feeding associated puerperal characteristics. Also, 3 studies used Saenghwa-tang as an intervention. Conclusions: Saenghwa-tang can be commonly used for the purpose of prevention and care of the postpartum symptoms within the first 1~2 weeks after childbirth for 10 days. Also, various prescriptions of herbal medicine may be used depending on the diseases or symptoms, and can be conducted with other treatments like acupuncture, cupping, moxibustion, pharmacopuncture and chuna manipulation.

• 한국재료학회지
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• 제24권2호
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• pp.87-92
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• 2014

The Notched Ring Test(NRT) has proven to be very useful in determining the slow crack growth behavior of polyethylene pressure pipes. In particular, the test is simple and an order of magnitude shorter in experimental times as compared to the currently used Notched Pipe Test(NPT), which makes this method attractive for use as the accelerated slow crack growth test. In addition, since the NRT specimen is taken directly from the pipe, having maintained the cross-section, processing induced artifacts that would affect the slow crack growth behavior are not altered. This makes the direct comparison to the slow crack growth specimen in pipe from more meaningful. In this study, for comparison with other available slow crack growth methods, including the NPT, the stress intensity factor equation for NRT specimen was developed and demonstrated of its accuracy within 3% of that obtained from the finite element analysis. The equation was derived using a flexure formula of curved beam bending along with numerically determined geometric factors. The accuracy of the equation was successfully tested on 63, 110, 140, 160, 250, and 400 mm nominal pipe diameters, with crack depth ranging from 15 % to 45 % of the pipe wall thickness, and for standard dimensional ratio(SDR) of 9, 11, and 13.6. Using this equation the slow crack results from 110SDR11 NRT specimen were compared to that from the NPT specimen, which demonstrated that the NRT specimen was equivalent to the NPT specimen in creating the slow crack, however in much shorter experimental times.

• Steel and Composite Structures
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• 제27권4호
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• pp.509-523
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• 2018

This paper presents experimental results on the residual bond-slip behavior of high strength concrete-filled square steel tube (HSCFST) after elevated temperatures. Three parameters were considered in this test: (a) temperature (i.e., $20^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$, $800^{\circ}C$); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 HSCFST specimens were designed for push-out test after elevated temperatures. The load-slip curves at the loading end and free end were obtained, in addition, the distribution of steel tube strain and the bond stress along the anchorage length were analyzed. Test results show that the shape of load-slip curves at loading ends and free ends are similar. With the temperature constantly increasing, the bond strength of HSCFST increases first and then decreases; furthermore, the bond strength of HSCFCT proportionally increases with the anchoring length growing. Additionally, the higher the temperature is, the smaller and lower the bond damage develops. The energy dissipation capacity enhances with the concrete strength rasing, while, decreases with the temperature growing. What is more, the strain and stress of steel tubes are exponentially distributed, and decrease from the free end to loading end. According to experimental findings, constitutive formula of the bond slip of HSCFST experienced elevated temperatures is proposed, which fills well with test data.

• 대한화학회지
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• 제24권2호
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• pp.91-100
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• 1980

축방향대칭을 갖는 팔면체 $[Ti(III)A_3B_3]$형태 착물의 자기모멘트를 계산하는 식을 유도하여 distortion parameter$({\delta})$, 스핀-궤도 상호작용상수$({\zeta}')$ 및 orbital reduction factor의 실험치를 사용하여 이들 착물의 자기모멘트를 계산하였다. 축방향으로 일그러진 팔면체 $[Ti(III)A_3B_3]$형태 착물의 계산한 자기모멘트가 실험치와 비교적 일치하였다. 팔면체로부터 축방향 일그러짐이 커짐에 따라 그리고 orbital reduction factor가 감소함에 따라 계산한 자기모멘트의 값이 크게 감소하였다. 축방향대칭보다 낮은 리간드장으로 일그러진 팔면체착물의 자기모멘트를 계산하는 방법을 발전시켰으며 계산한 자기모멘트를 기초로 하여 일그러진 팔면체 $[Ti(III)A_3B_3]$형태 착물의 구조를 논의하였다.

• 콘크리트학회논문집
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• 제13권4호
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• pp.305-313
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• 2001

본 연구에서는 콘크리트 열전도율의 영향인자에 대하여 TLPP원리를 응용한 QTM-D3 장비를 이용하여 실험을 실시하였고, 이들 실험결과를 이용하여 콘크리트의 열전도율을 예측하는 모델식을 제안하였다. 본 연구를 통하여 얻은 결론은 다음과 같다. 콘크리트, 모르타르 및 페이스트의 열전도율에 미치는 주요 영향인자를 구명하기 위해 본 연구에서 선택된 실험변수는 재령, 골재 함유량, 시멘트 함유량, 결합재 종류, 잔골재율, 시편의 온도 및 함수상태로 총 7가지이다. 이중에서 골재 함유량과 함수상태가 콘크리트 열전도율의 주요 영향인자임을 알 수 있었다. 그리고 시멘트 사용량이 많은 페이스트나 모르타르의 경우 시멘트 함유량이나 결합재 종류에 의해서도 열전도율이 영향을 받고 있다. 그러나 재령은 콘크리트의 열전도율에 큰 영향을 미치지 않음을 알 수 있었다. 콘크리트 열전도율에 주요 영향인자인 골재 함유량, 잔골재율, 시편의 온도 및 함수상태를 이용하여 콘크리트의 열전도율을 계산할 수 있는 모델식을 제안하였다.

• 대한기계학회논문집A
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• 제41권4호
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• pp.321-327
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• 2017

본 연구에서는 수평 자세에서의 TIG 용접 시 반응표면법(RSM)을 이용하여, 최적의 이면비드 형상을 구하는 연구를 진행하였다. 입력변수로는 베이스 전류, 피크 전류, 용접속도를 선정하였고, 이면비드 폭을 용접품질에 관한 출력변수로 하여 목표값을 5.4 mm로 설정하였다. Box-Behnken 실험계획법에 따라 실험을 진행하였고, 비드 폭에 관한 2차 회귀모형을 구한 후, F-테스트를 이용하여 회귀모델을 검정하였다. 그리고 망목특성의 호감도 함수를 사용하여 이면비드 형상을 평가함으로써 최적화를 수행하였다. 이렇게 도출된 최적의 용접조건은 코드화된 값으로 베이스 전류; 0.9204, 피크 전류; 0.8676, 용접속도; 0.3776이었다. 검증실험 결과 목표값에 근접한 5.38 mm의 이면비드 폭을 얻을 수 있었다.

• 한국농공학회지
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• 제23권2호
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• pp.35-44
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• 1981

This experiment was conducted to find out the consumptive use of irrigated water for calculation of duty water in paddy rice. Tall statured Japonica rice varieties, Nongbaek (early), Jinheung (medium) and Akibare (late), and short statured Tongil typed varieties, Josaeng Tongil(early), Suweon 264 (medium) and Suweon 258(late) were planted on the experimental farm of Kon-Kuk University in 1979. The results obtained in this study were as follows: 1. During the experimental period, the daily mean temperature was almost similar, the relative humidity was higher as much as 2.8%, the amount of rain fall was 100mm less and the pan evaporation was 70mm less compared with those of 30 years average, respectively. 2. The paddy soil was silty loam, which was suitable for the rice cultivation. 3. Varietal differences were find out for plant height, culm length, number of tillers, number of panicles, heading date, matured grain ratio, 1000-grain weight and rough rice yield. This difference might he the cause of varietal difference of the consumptive use of irrigated water during the rice growing period. 4. The evapotranspiration was gradually increased after transplanting and showed the peak from booting to heading stage of rice varieties. The average evapotranspiration through the whole growing period was 5.67-5. 80mm/day for tall statured Japonica varieties, and 5.99-6. 39mm/day for short statured Tongil typed varieties. 5. The ratio of evapotranspiration to pan-evaporation through the whole growing period was 1.49-1.50 for Japonica varieties, and 1.60-1.66 for Tongil typed varies. 6. Average amount of percolation in paddy field was 3. 62mm/day through the whole growing period of rice plant. 7. K-value in Blaney & Criddle formula was 0.94-0.98 for Japonica varieties and 1.02-1.08 for Tongil typed varieties, and coefficient consumptive water use (Kc-value) was 0.95-1.02 for Japonica varieties and 1.04-1.12 for Tongil typed varieties in this study. The modified coefficient for consumptive water use, which was calculated from data collected through the country including this study, was as follows;