• 대한한방내과학회지
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• 제11권2호
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• pp.148-169
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• 1990

The Present experiment was designed to investigate the effects of Soo Jeom San on the function of heart and digestive organs. And thus it was analyzed the total acidity, recovery effect, and the other various enzyme activities such as ATPase, Creatine kinase, Aspartate transaminase, and Lactate dehydrogenase. The results were obtained as follows : 1. The Total acidity decreased after Soo JeomSan administration for 6 days, however the total acidity inoreased after the drug administration for 9 days, these phenomena demonstrate that Soo Jeom San acts as a dual factor. The mechanism of decreasing the total acidity was considered to the inhibition of ATPase activity used for HCI active transport from parietal cells. 2. Soo Jeom San recovered the islets of Langerhans which was disrupted by streptozotocin. The recovery mechanism was suggested that Soo Jeom San stimulates the ${\beta}-cell$ proliferation. 3. Soo Jeom San inhibited the enzyme activities such as Creatine kinase and Aspartate transaminase, however the drug activated Lactate dehydrogenase. According to the obtained results, Soo Jeom San may be used for curing gastric ulcer and myocardiac infarction.

• Journal of Power Electronics
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• 제9권6호
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• pp.823-834
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• 2009

This paper proposes a high-efficiency single-stage ac/dc converter. The proposed converter features low voltage stresses and reduced switching losses. It operates at the boundary of discontinuous- and continuous-conduction modes by employing variable switching frequency control. The turn-on switching loss of the switch can be reduced by turning it on when the voltage across it is at a minimum. The voltage across the bulk capacitor is independent of the output loads and maintained within the practical range for the universal line input, so the problem of high voltage stress across the bulk capacitor is alleviated. Moreover, the voltage stress of the output diodes is clamped to the output voltage, and the output diodes are turned off at zero-current. Thus, the reverse-recovery related losses of the output diodes are eliminated. The operational principles and circuit analysis are presented. A prototype circuit was built and tested for a 150 W (50V/3A) output power. The experimental results verify the performance of the proposed converter.

• 한국생산제조학회지
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• 제20권4호
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• pp.440-445
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• 2011

This paper presents a new regenerative brake system of electric vehicles that employs a continuous variable transmission(CVT) and a flywheel. The developed device has advantages over existing regenerative brakes from a standpoint of reliability and versatility in actual driving conditions. The system consists of a CVT, two wheels, a flywheel, a coupling and auxiliary powertrain components. The CVT is designed as a combination of two cones and a roller, which causes the velocity difference between the wheel and the flywheel. The power flow of the flywheel system is controlled by the CVT roller and the coupling through step motors. A prototype has been developed and then its performance has been investigated for various operating conditions. Results show that the storage efficiency of the flywheel is much affected by the vehicle's velocity and it is reduced below 20% for high speed, as compared to the 25% efficiency for an ideal condition. The CVT is a primary factor for lowering the flywheel efficiencies due to large friction and slipping between the cone and the roller.

• 한국미생물·생명공학회지
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• 제23권5호
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• pp.609-616
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• 1995

Effects of lactate concentration, temperature, counter ions, pH as well as voltage (current) in batch electrodialysis (ED) experiments with a 3-compartment unit were investigated. The applied voltage was found to be the most critical factor as expected. The electrodialysis rate increased with the lactate concentration of the source solution. The amount of lactate transferred was limited by the lactate concentration difference between cathode and permeate compartments. The electrodialysis rate did not heavily depend on temperature change. The electrodialysis rate of NH$_{4}$-lactate was faster than that of Na-lactate and both lactates showed the highest electrodialysis rate at a pH of 4.0. A little amount of non-ionic glucose diffused through the anionic membrane to the permeate compartment. To test the effectiveness of the in situ recovery of lactic acid from fermentation broth by ED, three cases of batch culture were carried out; pH control only, ED only, and pH control and ED. The case with both pH control and ED was more efficient than that with pH control only in the aspects of productivity and product yield.

• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1101-1108
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• 2009

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제30권4호
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• pp.339-344
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• 2004

The purpose of this study was to evaluate neurosensory disturbance associated with implant surgery performed by implant practitioner (n=47) composed of trained oral surgeon, periodontist, prosthodontist. The incidence, type and duration of sensory disorder were investigated. Anatomical factor of the patient and experience of operator were also evaluated. The result revealed high incidence of inferior alveolar nerve damage (45%) regardless of experience of implant practitioner. The sensory disturbance sustained within 6 months for 61% of cases, which revealed almost normal recovery of nerve function. Initial neurologic sign after nerve damage was not coincide with their consequence of recovery. Half of the practitioners tried surgical intervention to the implants such as removing the fixture, partial unscrewing or re-implant shorter fixture, of which trial regarded as effective measure for 53% of cases. The result indicates that the objective method of sensory nerve evaluation should be introduced to the implant practitioners and the importance of informed consent for possibility of nerve damage in mandibular implant fixation.

• 복식문화연구
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• 제13권6호통권59호
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• pp.896-909
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• 2005

In need of studies on the kinds and structure of thread, the biggest variable factor in knitwear patterns, this study attempts: to examine the physical properties by thread type to basically establish systematic data in order to utilize various mixture and structure of yarn and to contribute to the development of optical patterns by building a systemic and scientific methods to produce knit wear patterns though a statistical analysis of the relation between the variations and physical properties. The results is as follows: with time, a feature of knit, which causes instability making it difficult to maintain the original shape, related to material properties, the weight and expansibility recovery rate have the greatest influence on the variation of wale lengths, though the amount varies by material. The variation of course contraction is closely related to density, the dense fabrics showing the highest values, due to the bust of the human body, the wale length variation of the front is greater than that of the back, by a regression analysis of material properties and the variations is obtained showing the weight, density and expansibility recovery rate have the greatest influence on the wale extension and course contraction of knit.

• 한국통신학회논문지
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• 제22권10호
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• pp.2246-2255
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• 1997

디지털 수신기의 타이밍 복원 방법 중, 영점교차검출을 이용하는 다양한 접근 방법이 알려져 있다. Gardner는 BPSK/QPSK 신호에 적합한 타이밍 복원 방법을 제안하였으나 이를 다중레벨 PAM 신호에 적용할 경우 자체잡음의 증가 때문에 다중레벨 PAM 신호에 사용하기 부적합하다. 본 논문에서는 Gardner 방법을 다중레벨 PAM신호에 적용하였을 경우 타이밍 지터의 증가로 인한 성능 저하 현상을 분석하고, 이를 해결하기 위한 타이밍 함수를 제안한다. 제안된 타이밍 함수는 다중레벨 PAM 신호가 천이할 때 영점을 교차하도록 주위의 신호를 사용하여 보정하였고 이에 의하여 타이밍 지터의 크기가 현저하게 감소되었다. 제안된 타이밍 함수의 이론적 성능 분석을 통해 타이밍 함수의 계수를 최적화하고, 전산 모의 실험에서 추가 대역폭(roll-off factor)과 SNR 등을 변화시키며 Gardner 방법과 제안된 방법의 성능을 비교한다.

• Journal of Advanced Marine Engineering and Technology
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• 제11권4호
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• pp.59-74
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• 1987

In this dissertation, a complete model of commutatorless static Kramer type slip power recovery system of 3.phi. induction motor has been designed and tested in the laboratory, and the experimental results are compared with the numerical values. The main results of this study are summerized as follows. (1) Maintenance and repair of the mechanical commutator is obviated by adopting a thyristor commutator in place of the mechanical commutator in the conventional Kramer system. (2) The experimental results of developed torque, and stator current are generally coincided with the numerical values obtained by the derived equation, proving their validity. (3) This system is simulated and the following operational characteristics are obtained with suitable design values : (a) The speed control range of 7:1 is obtained when the turn ratio of induction motor is lowered to about 3:1 to 4:1 and the generating constant of auxiliary synchronous motor is increased to 120-175 range. (b) Its efficiency can be increased to 75-85%, the range for static Scherbius system and its power factor takes values in the range of 65-85%, which is twice of the range for static Scherbius system.

• Journal of the Korean Wood Science and Technology
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• 제27권4호
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• pp.20-29
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• 1999

Temperature has important effect on mechanical properties of wood. These effect needs to be understood and taken into account in the structural use of wood. Furthermore, the effect of cooling after exposing to high temperature must be explained. In this study, the effect of temperature, exposure time, specific gravity, and cooling on bending properties were investigated. The boundary temperatures at which bending MOE and MOR reduced rapidly were approximately $200^{\circ}C$ and $150^{\circ}C$, respectively. This boundary temperature was nearly constant with independence of species(specific gravity), exposure time, and cooling. Above the boundary temperature, the effect of exposure time was increased with temperature and the reduction of bending MOE and MOR for Japanese Larch with relatively higher specific gravity was smaller than that of Hem-fir. The recovery of bending MOE and MOR after cooling was also more significant above the boundary temperature than below. The degree of cooling effect was larger for MOR than MOE. Consequently, bending properties of wood in elevated temperatures should be considered in terms of the boundary temperature, $200^{\circ}C$ for bending MOE, $150^{\circ}C$ for MOR, and these boundary temperatures must be considered an important factor. Furthermore, to evaluate the safety of structure, the recovery after cooling should be considered.