• 대한한방내과학회지
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• 제19권2호
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• pp.88-106
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• 1998

This study was designed to elucidate the antiinflammatory, cardiovascular, antithrombotic, and analgesic effect of Sambitang. The antiinflammatory effects was measured by the method of carrageenin induced edema, protein leakage test using CMC-pouch, and the effect of Sambitang on the cardiovascular system was observed by the change of flow rate of Ringer solution in the vascular system in the ear of rabbit, and the contraction and dilatation of rat tail artery. Death rate, platelet aggregation, plasma coagulation activity was observed for the measurement of the anticoagurative effect of Sambitang, and the analgesic effect was measured by the acetic acid method and hot plate method. The result was as follows: 1. Sambitang administration, edema and protein leakage was significantly decreased. 2. The drug increased the auricular blood flow in rabbit. 3. The drug relaxed the artery contraction by pretreated norepinephrine in rat. 4. The drug inhibited the death rate of mouse which was led to thromboembo- lism by serotonin and collagen. 5. The drug inhibited the platelet aggregation in rat. 6. The drug prolonged the prothrombin time and activated partial thromboplastin time on the test of plasma coagulation factor activity in rat, but was not valuable. 7. The slight anagesic effect of Sambitang extract was confirmed by the observation of writhing syndrome, paw licking time, and escape time.

• 대한기계학회논문집B
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• 제28권2호
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• pp.135-145
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• 2004

An experimental study is conducted to investigate the flow and heat transfer characteristics of a multi-tube inserted impinging jet. Four different multi-tube devices are tested for various nozzle-to-plate distance. Flow visualization by smoke-wire method and velocity measurements using a hot-wire anemometer are applied to analyze the flow characteristics of the multi-tube insert impinging jet. The local heat transfer coefficients of the multi-tube inserted impinging jet on the impingement surface are measured and the results are compared to those of the conventional jet. In multi-tube inserted system the multi-tube length plays an important role in the flow and heat transfer characteristics of the jet flow. With multi-tube insert of I3d4 and I6d4 which has relatively longer tube length than the multi-tube-exit of I3d1 and I6d1, the flow maintains its increased velocity far downstream due to interaction between adjacent flows. For the small H/D of 4, the local heat transfer coefficients of multi-tube inserted impinging jet are much higher than those of the conventional jet because the flow has higher velocity and turbulent intensity by the use of the multi-tube device. At large gap distance of H/D=12, also higher heat transfer rates are obtained by installing multi-tube insert except multi-tube insert of I3d1.

• 열처리공학회지
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• 제28권5호
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• pp.239-249
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• 2015

Various amount of NbC carbide was intentionally formed in a matrix-type cold-work tool steel by controlled amount of Nb and C addition. And the effect of NbC addition on the mechanical properties was investigated. Four alloys with different Nb and C contents were cast by vacuum induction melting, then hot forging and spheroidizing annealing were conducted. The machinability of the annealed specimens was examined with 3 different cutting tools. And tensile tests at room temperature were conducted. After quenching and tempering, hardness and impact toughness were measured, while wear resistance was evaluated by disk-on-plate type wear test. The increasing amount of NbC addition resulted in degraded machinability with increased strength, whereas the absence of NbC also led to poor machinability due to high toughness. After quenching and tempering, the additional NbC improved wear resistance with increasing hardness, whereas it deteriorated impact toughness. Therefore, it could be found that a moderate addition of NbC was desirable for the balanced combination of mechanical properties.

• 터널과지하공간
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• 제8권3호
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• pp.184-193
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• 1998

방사성 폐기물의 안전한 처분을 위해서는 암반의 역학적, 열적, 유체 거동 뿐 아니라 암반과 물 사이의 물리 화학적 상호작용을 이해할 필요가 있다. 또한 지질구조, 지하현지응력, 습곡, 열수작용, 마그마의 관입, 판구조 등과 같은 많은 조건을 모델링하고 예측하기 위해서는 암석의 역학적, 수리적 특성을 알아야 한다. 이 연구는 심부 암반에 폐기물 처분과 관련된 암석역학적인 사항들에 대해 연구들에 기초하고 있다. 이 논문은 변하는 온도 상태에서 암반의 역학적 수리적 거동, 암반의 열-수리-역학적 상호작용 해석과 불연속 암석의 거동 특성 등을 포함한다. 역학적 특성은 Interaken 암석역학 시험 시스템으로 측정되었으며, 수리적 특성에는 순간 증압 투수계수 측정 시스템이 사용되었다. 모든 결과에서 암석 특성은 온도 변화에 민감함을 보였다.

• Biomolecules & Therapeutics
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• 제22권5호
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• pp.445-452
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• 2014

The purpose of this study was to investigate the therapeutic effects of DA-9801, an optimized extract of Dioscorea species, on diabetic peripheral neuropathy in a type 2 diabetic animal model. In this study, db/db mice were treated with DA-9801 (30 and 100 mg/kg, daily, p.o.) for 12 weeks. DA-9801 reduced the blood glucose levels and increased the withdrawal latencies in hot plate tests. Moreover, it prevented nerve damage based on increased nerve conduction velocity and ultrastructural changes. Decrease of nerve growth factor (NGF) may have a detrimental effect on diabetic neuropathy. We previously reported NGF regulatory properties of the Dioscorea genus. In this study, DA-9801 induced NGF production in rat primary astrocytes. In addition, it increased NGF levels in the sciatic nerve and the plasma of type 2 diabetic animals. DA-9801 also increased neurite outgrowth and mRNA expression of Tieg1/Klf10, an NGF target gene, in PC12 cells. These results demonstrated the attenuation of diabetic peripheral neuropathy by oral treatment with DA-9801 via NGF regulation. DA-9801 is currently being evaluated in a phase II clinical study.

• 한국산림과학회지
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• 제60권1호
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• pp.37-44
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• 1983

요소수지(尿素樹脂)의 변성제(變性劑)로서 열가망성(熱可望性)의 아세톤수지(樹脂)를 첨가(添加)하고 합판(合板)의 접착력(接着力) 및 목파율(木破率)에 미치는 영향(影響)을 조사(調査)하였다. 결론(結論)을 요약(要約)하면 다음과 같다. 1) 합판(合板)의 접착력(接着力)과 목파율(木破率)은 열판온도(熱板溫度) $120^{\circ}C$에서 제조한 것이 가장 좋은 값을 보였으나 아세톤수지(樹脂)의 혼합비율(混合比率)이 증가(增加)함에 따라서 그 값은 점차 감소(減少)되었다. 2) 아세톤수지(樹脂)의 몰비율(比率)은 합판(合板)의 접착력(接着力) 및 목파율(木破率)에 영향(影響)을 미치지 않았다. 3) 아세톤수지(樹脂)를 혼용(混用)한 합판(合板)은 요소수지(尿素樹脂)만으로 접착(接着)된 합판(合板)의 접착력(接着力) 및 목파율(木破率)을 능가하지 못했다. 따라서 아세톤수지(樹脂)는 요소수지(尿素樹脂)의 변성제(變性劑)는 부적당(不適當)하였다.

• The Korean Journal of Physiology and Pharmacology
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• 제14권5호
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• pp.285-289
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• 2010

In the present study, the antinociceptive profiles of $Campanula$ $punctata$ extract were examined in ICR mice. The $Campanula$ $punctata$ contain a large dose of saponin. $Campanula$ $punctata$ extract administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate tests. In addition, $Campanula$ $punctata$ extract attenuated the writhing numbers in the acetic acid-induced writhing test. Furthermore, the cumulative nociceptive response time for intrathecal (i.t.) injection of substance P ($0.7{\mu}g$) was diminished by $Campanula$ $punctata$ extract. Intraperitoneal (i.p.) pretreatment with yohimbine (${\alpha}_2$-adrenergic receptor antagonist) attenuated antinociceptive effect induced by $Campanula$ $punctata$ extract in the writhing test. However, naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist) did not affect antinociception induced by $Campanula$ $punctata$ extract in the writhing test. Our results suggest that $Campanula$ $punctata$ extract shows an antinociceptive property in various pain models. Furthermore, this antinociceptive effect of $Campanula$ $punctata$ extract may be mediated by ${\alpha}_2$-adrenergic receptor, but not opioidergic and serotonergic receptors.

• 에너지공학
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• 제24권2호
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• pp.72-78
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• 2015

본 연구에서는 가스 터빈의 효율을 증대시키는데 사용되는 리큐퍼레이터의 성능에 대한 실험적 연구를 수행하였다. 본 연구에서 채택한 리큐퍼레이터는 오프셋 스트립 휜을 가지는 대항류 열교환기이다. 기존에 제시된 상관식 및 이상상태 사이클 해석을 통하여 최적화된 리큐퍼레이터의 형상을 결정하였다. 리큐퍼레이터의 성능을 평가하기 위해 실험연구를 수행하였다. 특히 리큐퍼레이터의 고온부 입구 온도를 변화시키면서 실험을 수행하였다. 또한 실험 결과를 기존에 제시되어 있던 상관식들과 비교를 하였다. 그 결과 압력강하는 실험결과와 상관식이 잘 맞지 않았지만 유용도는 실험결과와 상관식이 잘 일치하는 것을 확인하였다.

• Tribology and Lubricants
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• 제33권1호
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• pp.15-22
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• 2017

Because the running speed of vehicles is increasing and a shorter braking distance is required, high heat-resistant brake pads are needed to satisfy the requirements of customers and car makers. In the near future, hazardous materials such as Cu, Cr, Zn, and Sb will be restricted from use in friction materials. Ceramic composites reinforced by carbon fibers are good candidates for eco-friendly friction materials. In this study, we develop ceramic composite friction materials. The friction materials are composed of carbon fibers, Si, SiC, graphite, and phenol resin and are prepared by hot forming and heat treatment at high temperatures. The density, void ratio, and compressive strength are $1.59-1.66g/cm^3$, 16.6-20, and 70-90 MPa, respectively. Friction and wear tests are performed using a pin-on-plate-type reciprocating friction tester at 25, 100, and $200^{\circ}C$. The counterpart material is a CrMoV steel extracted from a KTX brake disc. Friction coefficient, wear amount, and wear mechanism are measured and examined. We determine that the friction coefficients depend on the temperature and the fluctuation of the friction coefficients is larger at higher temperatures. The amount of wear increases with the surface temperatures of the specimens. The tribological properties of the developed composites are similar to those of a Cu-based sintered friction material. Through this study, it is confirmed that ceramic composite materials can be used as friction materials.

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