• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.07a
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• pp.309-316
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• 2003

Generally, sesame are dried on the field after being harvested in Korea. Since harvesting season is rainy autumn and sesame drying is mainly affected sun and natural wind, it is difficult to dry sesame in time. Moreover, sesame threshing by hand is very laborious work. Therefore, tractor mounted sesame thresher which threshes sesame bundles fed in upside down and conveyed along threshing bar was developed to mechanize sesame threshing and to reduce labor cost in this research. the thresher was equipped with a threshing bar which beats sesame bundles and a three layer sieve which screens sesame. The results are summarized as follows ; 1 The sesame thresher was consisted of a hitting-stick, a feeding chain conveyor, a threshing bar, conveyor belt, and the three-layer shaking sieve. 2. In threshing test, prototype thresher showed maximum threshing ratio 98.5%, 98.7% at 14, 17 cpm beating rate respectively. 3. In screening test, prototype sieve showed maximum threshing ratio 97.2% at 12$^{\circ}$ of inclined angle and 220 cpm of sieve vibrating rate. 4. Prototype showed 98.7% of threshing ratio, 1.3% of threshing loss, 97.0% of screening ratio, 0.7% of screening loss on the rest condition of 15 sesame bundles/min of feeding rate, 14 cpm of beating rate, 220 cpm of sieve vibrating rate. 5. The working performance of prototype was 0.5hr/10a. It was 9.6 times more efficient than manual work. And, operation cost of prototype was saved by 45.9% compared to manual work.

• Journal of Chest Surgery
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• v.33 no.5
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• pp.398-406
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• 2000

Background: Cardiac atrium is an endocrine gland secreting a family of natriuretic peptides. The secretion of atrial natriuretic peptide(ANP) had been shown to be controlled by variable factors. The change in atrial dynamics have been considered as one of the most prominent stimuli for the stimulation of ANP secretion. Hypoxic stress has been shown to increase cardiac ANP secretion. However, the mechanism by which hypoxia increases ANP secretion cardiac ANP secretions. However, the mechanism by which hypoxia increases ANP secretion has not to be defined. Therefore, the purpose of the present study was tow-fold: to develop a protocol to defined the effect of hypoxia on ANP secretion in perfused beating rabbit atria and to clarify the mechanism responsible for the accentuation by hypoxia of ANP secretion. Material and Method: Experiments have been done in perfused beating rabbit atria. ANP was measured by radioimmunoassay. Result: Hypoxic stimulus with nitrogen decreased atrial stroke volume. The decrease in atrial stroke volume recovered basal level during the period of recovery with oxygen. ANP secretion and the concentration of perfusate ANP in terms of extracellular fluid(ECF) translocation which reflects the rate of myocytic release of ANP were increased by hypoxia and returned to basal levels during the recovery. Changes in ECF translocation paralleled by hypoxia and returned to basal levels during the recovery. Changes in ECF translocation paralleled to that of atrial stroke volume. At the start of recovery in atrial storke volume, ECF tranalocation incrased for several minutes. The above responses were stable and reproducible. Glibenclamide treatment prevented the recovery in atrial stroke volume. Increments by hypoxia of ANP secretion and ANP concentration were suppressed by glibenclamide. Conclusion: These results indicate that hypoxia incrased atrial myocytic ANP release and that the mechanism responsible for the accentuation is partially related to the change in K+ATP channel activity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.212-217
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• 1998

Reynolds equation, which describes behavior of fluid film in journal bearing, basically satisfies mass conservation. But, boundary conditions usually used with this equation, e.g. half Sommerfeld or Reynolds boundary conditions, cannot fulfill this natural law of conservation. In the case of connecting rod bearing, where applied load is dynamic and its magnitude is relatively large, such unrealistic boundary conditions have serious influence on calculation results, especially on lubricant flow rate or power dissipation which are important parameters in thermal analysis. Another important factor in the analysis of connecting rod bearing is elastic deformation of bearing support structure which is relatively flexible. In this paper, EHL analysis of connecting rod beating is performed using mass-conserving boundary condition. Elastic deformation of bearing support structure and application of mass-conserving boundary condition have significant effects on the performances of connecting rod bearing.

• Archives of Pharmacal Research
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• v.17 no.3
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• pp.150-153
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• 1994

Ethanolic extract of Daucus carota (DC) at the dose of 10-100 mg/kg caused a dose-dependent fall in systolic and diastolic arterial blood pressure in nomotensive anesthetized rats. These effects were not blocked by atropine (1 mg/kg) and pretratment with DC did not alter the pressor response to norepinephrine indicating that cardiovascular effects of DC are independent of cholinergic or adrenergic recptors involvement. In spontaneously beating guinea-pig paired atria, DC induced a concentration-dependent (03-5 mg/ml) decrease in force and rate of atrial contractions. In rabbit thoracic aorta, DC caused inhibition of $K^+$-induced contractions at similar concentrations. These results suggest that the extract may exhibit $Ca^{2+}$ channel blocking-like direct relaxant action on cardiac and smooth muscle preperations and this action may be responsible for its hypotensive effect observed in the in vivo studies.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1263-1266
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• 1996

We have experienced a case of coronary artery bypass surgery without extracorporeal circulation through limited anterior thoracotomy. The lesion was a single vessel disease involving the take off of the left anterior descending artery(LAD) which showed tubular lesion with irregular contour and eccentric stenosis of more than 95% luminal narrowing. Percutaneous transluminal coronary angioplasty(PTCA) seemed to have moderate success rate and moderate complication rate. A segment of left internal mammary artery(LIMA) from the second rib down to the sixth rib was harvested through the bed of resected fourth costal cartilage. Anastomosis between LIMA and LAD was performed under beating condition. The patient was extubated in the operation room and showed excellent postoperative course without complications. The coronary angiography on the postoperative 7th day revealed good patency at the anastomosis site.

• Journal of Chest Surgery
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• v.29 no.4
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• pp.365-372
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• 1996

In an attempt to evaluate the effect of St. Thomas' hospital cardioplegic solution (STH) I and II on the cultured rat myocardial cells, beating rate, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (Irtrazolium MTT) and lactate dehydrogenase activity were investigated, and also light and electron microscopic studies were carried out. After rat myocardial cells were cultured for 72 hours, cells were treated with STH I or with STH H solution for 30 and 120 min. and thereafter myocardial cells were cultured in control medium for 24 hours. The results obtained were as follows : 1. Beating rate was 154 times per min. in control group, 141 times per min. in STH I solution(for 2. 120 min.)-treated group and 145 times in STH ll solution (for 120 min.)-treated group. MTT absorbances by MTT assay were 102% in STH I solution (for 120 min.)-treated group and 93% in STH ll solution (for 120 min.)-treated group compared with control group. 3. The amount of lactate dehydrogenase released into the medium were 123% in STH I solution (for 120 min.)-treated group and 109% in STH H solution (for 120 min.)-treated group compared with control group. 4. In the light microscopy examination, myocardial cells showed no differences between experimental and control groups in their number and shape. 5. In the electron microscopy examination, myocardial cells treated with STH I solution showed fewer destroyed mitochondria compared to STH ll solution-treated group. These results suggest that both 51. Thomas'cardioplegic solution STH 1 and STH H have no cytotoxicity on cultured rat myocardial cells, but STH H solution has more protective effect on myocardial cells compared to STH I solution.

• Korean Journal of Clinical Pharmacy
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• v.21 no.1
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• pp.6-13
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• 2011

Bolus intravenous injection of adenosine resulted the temporal decrease of systemic blood pressure and heart rate in the anesthetized rats. Adenosine also resulted the persistent decrease of contractility and heart rate in the isolated spontaneously beating rat right atria. Both of the above inhibition effets of adenosine were increased by the pretreatment of NBI (nitrobenzylthioinosine), whitch is an adenosine transport inhibitor, but decreased by the pretreatment of 8- phenyltheophy1line, which is an adenosine antagonist. In isolated thoracic aorta ring segment of normotensive rats, intact rings were relaxed by adenosine ($42.3{\pm}8.7%$) and ATP ($85.9{\pm}15.8%$) in the concentration of $10^{-4}M$, but rubbed rings were relaxed by adenosine ($35.2{\pm}1.9%$) and ATP ($11.3{\pm}9.0%$) in $10^{-4}M$. After pretreatment of L-NAME (N-Nitro-Larginine methyl ester), which is an NO inhibitor, adenosine-induced relaxation was not affected, but ATP-induced relax ation was significantly inhibited (P<0.01). Meanwhile, adenosine resulted almost same as vasorelaxation in isolated thoracic aorta of SHR comparing to those of normotensive rats. But, vasodilation responses of ATP in intact rings of SHR are significantly inhibited comparing to those of normotensive rats. Adenosine-induced relaxation is attenuated after 8-phenyltheophylline pretreatment, but increased after NBI pretreatment. However, ATP-induced relaxations are not affected by 8-phenyltheophylline or NBI pretreatment. These results suggested that the hypotensive effects of adenosine was due to the decrease of contractile force and heart rate through the A1 receptor and vasodilation are mediated by A2 receptor of the vascular smooth muscle. And, the heart protective and vasodilation effects of adenosine might suggest that it would be useful in the acute treatment of coronary artery disease.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1076-1081
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• 2003

A new technique for generating millimeter-wave signals from a semiconductor laser is presented. The method multiples the signal frequency by using optical injection of short optical pulses at a sub-harmonic of the cavity round-trip frequency to drive the laser oscillating at its resonant frequency. A 32GHz signal is generated using a multisection semiconductor laser operated under continuous wave conditions, by injection optical pulses at a repetition rate equal to the fourth subhamonic(8GHz). The generated millimeter-wave signal exhibits a large submamonic suppression ratio(＞17 dB), large frequency detuning range (>300 MHz) low levels of phase-noise(-77.5 dBc/Hz), and large locking (>400 MHz)

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.31-36
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• 2005

Use of the high frequency motor spindles are increasing for the high speed machine tools recently. The important problem in the high speed spindles is to reduce and minimize the thermal effect by the motor and ball hearings. Thermal characteristics according to the bearing preload and spindle cooling are studied for the spindle with the oil mist lubrication and high frequency motor. Temperature distribution and thermal displacement according to the spindle speed, preload and flow rate are measured. Temperature distribution and thermal displacement of the high speed spindle system can be estimated reasonably by using the three dimensional model through the finite element method. The results of analysis are compared with the measured data. This study supports thermal optimization and find out more effective cooling condition. This paper show that the suitable preload and spindle cooling are very effective to minimize the thermal effect by the motor and ball bearings.

• Journal of Sasang Constitutional Medicine
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• v.13 no.1
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• pp.70-78
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• 2001

ADR유발성 심근독성에 대한 심근세포의 손상기전을 규명하기 위해 ADR의 독성을 MTT정량, NR정량, LDH활성도 및 심박동을 측정하였다. 배양된 심근세포에서 청심연자탕 전탕액의 심근세포 보호효과는 LDH활성도 측정과 심박동 측정을 통해 관찰할 수 있었다. 이 실험을 통해 다음과 같은 결과를 얻을 수 있었다. 1. ADR은 배양심근세포에서 세포의 생존능력을 떨어뜨렸고, LDH의 활성도를 높였으며, 심박동수를 감소시켰다. 2. 청심연자탕 전탕액은 배양심근세포에서 ADR에 의해 증가된 LDH 활성도를 유의하게 감소시켰다. 3. 청심연자탕 전탕액은 배양심근세포에서 ADR에 의해 감소된 심박동을 유의하게 증가시켰다. 이상의 결과를 통해 ADR은 신생 마우스에서 적출해낸 배양 심근세포에서 독성효과를 나타냈음을 알 수 있었으며, 청심연자탕 전탕액은 ADR에 의해 유발된 심근세포독성에 매우 효과적으로 방어효과를 나타냄을 알 수 있었다.