• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.85-94
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• 2002

Computational flow dynamics(CFD) has been frequently applied to the waste incinerators to understand the flow performance for various design and operating parameters. Though it needs many simplifications and complicated flow models, the reasonability of its results is not fully evaluated. For example, the inlet condition is calculated from an arbitrarily assumed properties of combustion gas release from the waste bed, since the combustion in the bed is difficult to be predicted. In this study, the computational modeling and calculation procedures of CFD for the grate type waste incinerator were evaluated using comparative simulations. Though the assumption method on the generation of the combustion gas directly affected the temperature and gas species concentrations, the overall flow pattern was dominated by the secondary air jets. The gaseous reaction could be included by assuming the release of the products of incomplete combusion from the bed. However, the reaction effficiency cannot not be directly evaluated from the species concentration, since it is not possible to simulate the actual co-existence of fuel rich or oxygen rich puffs over the bed. In predicting the turbulence, the higher order model, such as Reynolds stress model, gave difference shape of local recirculation zones, but similar results was acquired from the standard $k-{\varepsilon}$ model. Introducing radiation model was required for accurate temperature prediction, but it also caused heat imbalance due to the fixed temperature of the inlet, i.e. the waste bed. Thus, the computational modeling procedures on incinerators and the analysis of the predicted results should be progressed carefully. Though not validated experimentally, current simulation method is capable of comparative evaluation on the flow-related parameters such as the furnace shape and secondary air injection using identical inlet conditions. Quantitative analysis using measures of the residence time and mixing is essential to compare the flow performance efficiently.

• 한국수산과학회지
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• 제9권1호
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• pp.74-78
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• 1976

연료분사시기와 회전속도를 일정하게 했을때 3종류의 연료를 사용하여 압축비와 기관의 성능관계를 조사한 결과 다음과 같은 것이 밝혀졌다. 1. 4 cycle디젤기관의 압축비는 기관마력과 연료소자율과의 관계에서 A, B, C 3종류의 연료에 대해 각각 16, 18, 19의 최적압축비가 존재했으며, 이보다 압축비를 높이면 오히려 기관성능이 저하하고 최대출력도 감소한다. 2. 매시공급열량을 일정하게 했을때 연료 A, B에 대해서 16, 18의 최적압축비가 존재했으며 연료 C에 대해서는 정할수 없었다. 따라서 저 cetane number의 연료에서는 출력에 관계없이 가장 좋은 압축비는 결정할 수 없었다. 3. 발화지연은 압축비가 높을 수록 작았고, 감소율은 압축비가 클수록 작았다.

• 폴리머
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• 제27권2호
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• pp.113-119
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• 2003

폴리(에틸렌 테레프탈레이트) (PET)의 열처리 조건들 즉, 상대 습도, 온도 그리고 시간 등에 따라 나타나는 PET의 열적 특성과 결정화 거동에 대해서 연구하였다. PET샘플에 열처리를 수행한 후 수분 함유량, 유리 전이온도($T_g$), 그리고 결정화 온도($T_{\propto}$) 등의 변화를 조사하였다. 그리고 열처리된 PET시편에 대해서 결정화를 시키고 결정화도에 따른 열변형 온도(HDT)를 측정하였다. 또한 사출 성형으로 제작된 PET샘플의 열처리 후 잔류 응력의 완화를 편광 필름을 통하여 조사하였다. 열처리 시의 상대 습도, 온도, 그리고 시간이 증가함에 따라 PET샘플 내의 수분 함유량은 최대 6000 ppm이상 까지 증가하였다. $T_g$와 $T_c$는 시편 내에 수분 함유량이 증가할수록 감소하였다. PET샘플의 결정화도는 수분의 함유량이 증가함에 따라 증가되었다. 그러나 같은 양의 수분 함량에서 결정화도는 열처리의 조건에 따라 다르게 나타났다. PET샘플 내의 잔류응력의 완화는 열처리 조건에 따라 다르게 나타났으며, PET샘플 내에 잔류 응력이 감소할수록 최대 결정화도는 증가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.764-767
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• 2003

The characteristics of diesel spray have much effect on the engine performances such as power. fuel consumption rate and emissions. Therefore, the measurement of fuel spray characteristics is very important for the improvement of heat engine. The factors which control diesel spray characteristics are injection pressure, ambient temperature and density etc. Spray behaviors are visualized by using the high speed video camera and spray angle, spray penetration are measured. Experimental equations of spray penetration and spray angle were derived by using the experimental results. 1) Ambient temperature and density influence on the characteristics of diesel spray. 2) Experimental equation of spray penetration is expressed as follows 0＜t＜ $t_{b}$ ; $S_1$=11.628$\Delta$ $P^{0.485}$ $\rho$$_{a}$ $^{-0.478}$ $t^{1.337}$, $t_{b}$ ＜t; $S_2$=7.457$\Delta$ $P^{0.523}$ $\rho$$_{a}$ $^{-0.382}$ $t^{0.548}$ 3) Experimental equation of spray Angie is expressed as follows $T_{a}$ =293K; Tan($\theta$/2)=059($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.437}$, $T_{a}$ =473K; Tan($\theta$/2)=0588($\rho$$_{a}$ / $\rho$$_{f}$ )$^{0.404}$_{f}$ )$^{0.404}$

• 약학회지
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• 제41권2호
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• pp.247-254
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• 1997

The proteinase-activated receptor (PAR-2) belongs to the family of seven transmembrane region receptors, like the thrombin receptor, it is activated by specific proteolytic clea vage of its extracellular amino terminus and a synthetic peptide (SLIGRL). The earthworm protein fraction (EPF) extracted from Lumbricus rubellus elicted dose- and endothelium-dependent relaxations in phenylephrine-contracted rat thoracic aorta, whereas heat inactivated EPF (0.5 ${\mu}g$ /ml) had no effect. In the presence of the nitric oxide synthase inhibitor NG-methyl-L-arginine (1.8 micro M), EPF (0.5 ${\mu}g$ /ml)-induced relaxations were partially inhibited. Furthermore, EPF (0.5 ${\mu}g$ /ml) dramatically caused relaxation of thrombin-desenstized rat thoracic aorta. These results indicate that EPF activates PAR-2 in vascular endothelial cell. Intravenous injection of EPF (20 mg/kg, bolus) into anesthetized rats produced a marked depressor response. EPF (0 ~ 80 ${\mu}g$ /ml, gradient) was very effective on increasing of perfusion volume in rabbit ear vessel preparations. These results imply the usefulness of EPF as a vascular smooth muscle relaxant and indicate that the activation of PAR-2 may be a mechanism of EPF on hemokinetic improvement.

• 한방안이비인후피부과학회지
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• 제29권4호
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• pp.114-130
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• 2016

Objectives : This study is performed to investigate the therapy on tinnitus through the literature of Eastern and Western medicine. Methods : This study review the definition, etiology, classification, internal and external methods of treatment of tinnitus based on 50 articles of Eastern medicine, 16 articles of Western medicine about the treatment of tinnitus. Results : The results were as follows. 1. In Eastern medicine, the cause and mechanism of disease of tinnitus arose from the state of qi-blood deficiency, internal dampness-heat and depression stagnation. In Western medicine, there are mainly caused by damage to the auditory system the lower induced changes in the upper. 2. In Eastern medicine, differentiation of syndromes classifies clinical aspects, and cause and mechanism of disease. In Western medicine, it divides into an generating region, clinical and associated symptoms aspects. 3. In Eastern medicine, internal method of treatments of tinnitus are divided into four treatments. In Western medicine, internal methods of tinnitus are vasodilators, blood-flow improvers, Metabolism improvers etc. 4. In Eastern medicine, external method of treatments of tinnitus are paste preparation method, powder preparation method, pill preparation method, acupuncture & moxibustion method. In Western medicine, external method of treatments of Tinnitus are divided into injection, other surgical therapies and adjuvant therapy. Conclusions : Until now, there is no perfect, effective single treatment. We think that Eastern medicine approach and treatment can be helpful to overcome the limitations of tinnitus cure.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.807-816
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• 2012

The Three Mile Island Unit 2 (TMI-2) accident has been studied extensively, as part of both post-accident technical assessment and follow-up computer code calculations. The models used in computer codes for severe accidents have improved significantly over the years due to better understanding. It was decided to reanalyze the severe accident scenario using current state of the art codes and methodologies. This reanalysis was adopted as a part of the joint standard problem exercise for the Atomic Energy Regulatory Board (AERB) - United States Regulatory Commission (USNRC) bilateral safety meet. The accident scenario was divided into four phases for analysis viz., Phase 1 covers from the accident initiation to the shutdown of the last Reactor Coolant Pumps (RCPs) (0 to 100 min), Phase 2 covers initial fuel heat up and core degradation (100 to 174 min), Phase 3 is the period of recovery of the core water level by operating the reactor coolant pump, and the core reheat that followed (174 to 200 min) and Phase 4 covers refilling of the core by high pressure injection (200 to 300 min). The base case analysis was carried out for all four phases. The majority of the predicted parameters are in good agreement with the observed data. However, some parameters have significant deviations compared to the observed data. These discrepancies have arisen from uncertainties in boundary conditions, such as makeup flow, flow during the RCP 2B transient (Phase 3), models used in the code, the adopted nodalisation schemes, etc. In view of this, uncertainty and sensitivity analyses are carried out using simulation based techniques. The paper deals with uncertainty and sensitivity analyses carried out for the first three phases of the accident scenario.

• 한국방사선학회논문지
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• 제14권5호
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• pp.597-602
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• 2020

림프관 조영술에 사용하는 리피오돌의 온도에 따른 이동 속도 차이를 분석하여 검사의 효율성을 높이고 환자 및 시술자의 피폭선량을 감소하는 방안을 연구하였다. 0.014 inch Support Catheter에 Balloon Inflator를 이용하여, 일정한 압력으로 리피오돌을 주입하는 장치를 자체 제작한 후 Connecting Tube에 리피오돌을 충전하고 전열 기구를 이용 26 ℃, 36 ℃, 46 ℃의 온도로 주입과 동시에 Fluoroscopy를 촬영하였다. 리피오돌이 Support Catheter에서 20 cm 이동하는 시간을 측정하여 분석하였고, 통계적 유의성 확인 후 리피오돌을 적정 온도로 유지하는 방법을 고안하였다. 46 ℃ 환경에서 이동시간 평균은 11초, 36 ℃에서는 평균 13초, 26 ℃에서는 평균 17초 소요되었다. 리피오돌은 온도 상승에 따라 이동시간이 유의한 차이를 보였으며(p < .001), 온도가 높을수록 이동 속도가 빨라지는 것을 확인하였다. 림프관 조영술 시 상온에 노출된 리피오돌을 바로 주입하는 것보다 일정 온도로 가열하여 사용할 경우 주입속도를 높일 수 있는 동시에 림프관 안에서의 이동 속도를 향상할 수 있다.

• International Journal of Oral Biology
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• 제34권3호
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• pp.157-164
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• 2009

We recently described a novel animal model of trigeminal neuropathic pain following compression of the trigeminal ganglion (Ahn et al., 2009). In our present study, we adapted this model using male Sprague-Dawley rats weighing between 250-260 g and then analyzed the behavioral responses of these animals following modified chronic compression of the trigeminal ganglion. Under anesthesia, the rats were mounted onto a stereotaxic frame and a 4% agar solution ($10{\mu}L$) was injected in each case on the dorsal surface of the trigeminal ganglion to achieve compression without causing injury. In the control group, the rats received a sham operation without agar injection. Air-puff, acetone, and heat tests were performed at 3 days before and at 3, 7, 10, 14, 17, 21, 24, 30, 40, 55, and 70 days after surgery. Compression of the trigeminal ganglion produced nociceptive behavior in the trigeminal territory. Mechanical allodynia was established within 3 days and recovered to preoperative levels at approximately 60 days following compression. Mechanical hyperalgesia was also observed at 7 days after compression and persisted until the postoperative day 40. Cold hypersensitivity was established within 3 days after compression and lasted beyond postoperative day 55. In contrast, compression of the trigeminal ganglion did not produce any significant thermal hypersensitivity when compared with the sham operated group. These findings suggest that compression of the trigeminal ganglion without any injury produces prolonged nociceptive behavior and that our rat model is a useful system for further analysis of trigeminal neuralgia.

• 대한본초학회지
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• 제35권6호
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• pp.29-34
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• 2020

Objectives : Gyejigamchoyonggolmoryeo-tang (GT, Guizhigancaolonggumulitang in Chinese) is a herbal medicine to be prescribed for insomnia caused by anxiety induced by Heart-Heat and elevated Liver-Yang. In the present study, the onset time (sleep latency) and the duration time of sleep were measured to find out the sleep inducing effects of GT. The expression of c-fos immunohistochemistry was also measured at the ventrolateral preoptic area (VLPO) and tuberomammillary nucleus (TMN) site in brain. Methods : The onset time (sleep latency) and the duration time of sleep were measured 30 minutes after thiopental sodium injection. Thereafter, brain tissue was obtained and c-fos immunohistochemistry was performed on the VLPO and TMN sites. Results : GT statistically significantly reduced the sleep latency required to enter sleep, and significantly increased sleep duration time. GT significantly increased the number of c-fos immunohistochemical staining-positive cells in the sleep-inducing center (VLPO), whereas GT significantly decreased the number of c-fos immunohistochemical staining-positive cells in the arousal center (TMN). Conclusions : It could be concluded that the GT shortened the sleep latency and increased the duration time for sleep induced by thiopental sodium. And it was confirmed that the mechanism was to stimulate the sleep-inducing center (VLPO) and suppress the arousal center (TMN) in the brain. The results of this study are considered to be useful as scientific evidence that can be used clinically for the treatment of insomnia caused by anxiety.