• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.93-98
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• 2000

Unpredictable failures can occur due to the DHC (delayed hydride cracking) or the degradation of fracture toughness by hydride embrittlement in CANDU pressure tube which can result from the absorption of hydrogen or deuterium in the high temperature coolant. To investigate the hydride embrittlement of CANDU Zr-2.5Nb pressure tube, the transverse tensile test and the fracture toughness test were performed from room temperature to $300^{\circ}C$ using three different specimens which have an AR (As Received), 100, and 200 ppm hydrogen. As the amount of absorbed hydrogen was increased, the transverse yield strength and the ultimate tensile strength were also increased. In addition, as the test temperature became higher they were decreased linearly. While, at room temperature, the hydrogenbsorbed specimens represented the embrittlement which resulted in sudden decreasing of fracture toughness, the fracture characteristics became ductile such as AR specimen at high temperatures. Through the observation of fracture surface using SEM, it was found that the stress state of mixed mode could be related to the fissure which was believed to decrease the global fracture toughness.

• Archives of Plastic Surgery
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• 제47권4호
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• pp.297-300
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• 2020

Hyaluronidase, an enzyme that breaks down hyaluronic acid, has long been used to increase the absorption of drugs into tissue and to reduce tissue damage in cases of extravasation of a drug. With the increasing popularity of hyaluronic acid filler, hyaluronidase has become an essential drug for the correction of complications and unsatisfactory results after filler injection. For this reason, when performing procedures using hyaluronic acid filler, a sufficient knowledge of hyaluronidase is required. In order for hyaluronidase to dissolve a hyaluronic acid filler, it must interact with its binding sites within the hyaluronic acid. The reaction of a filler to hyaluronidase depends on the hyaluronic acid concentration, the number of crosslinks, and the form of the filler. Hyaluronidase is rapidly degraded and deactivated in the body. Therefore, in order to dissolve a hyaluronic acid filler, a sufficient amount of hyaluronidase must be injected close to the filler. If the filler is placed subcutaneously, injection of hyaluronidase into the filler itself may help, but if the filler is placed within a blood vessel, it is sufficient to inject hyaluronidase in the vicinity of the vessel, instead of into the filler itself. Allergic reactions are a common side effect of hyaluronidase. Most allergic reactions to hyaluronidase are local, but systemic reactions may occur in infrequent cases. Since most allergic responses to hyaluronidase are immediate hypersensitivity reactions, skin tests are recommended before use. However, some patients experience delayed allergic reactions, which skin tests may not predict.

• 한국물환경학회지
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• 제31권3호
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• pp.253-261
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• 2015

The purpose of this study is the efficient biological treatment of highly concentrated nitrate nitrogen by calcium ion control present within the pickling wastewater. In laboratory scale's experiments research was performed using a sequencing batch reactor and the evaluation of denitrification reaction in accordance with the injection condition of calcium ions, the surface properties of microorganisms, and the evaluation of sludge precipitability were performed. Results of the study showed that the denitrification reaction was delayed when injecting more than 600 mg/L of the calcium ion within the denitrification process. In addition, we observed the absorption form of calcium ions absorbed on the surface of microorganisms following an increase in the calcium ion dose. It was found that as the calcium ion dose increased the sludge precipitability also increased continuously and it is judged that a smooth denitrification induction is possible when treating the nitrate nitrogen by the calcium ion control of pickling waste water and the shortening of precipitation time enables a liquid operation to increase the reaction time.

• 한국식품조리과학회지
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• 제19권1호
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• pp.107-113
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• 2003

In a previous study, a dietary supplement was developed in our lab using natural herbal extracts against digest enzyme activity in GI tract for weight control. This natural herbal extracts could regulate absorption of glucose and lipid by the inhibition of digest enzyme activity. In this study, we screened the natural herbs that inhibit glucoamylase activity and developed an water extract of cinnamon. The cinnamon extract delayed and decreased the increment of carbohydrate degradation through the inhibition of glucoamylase activity in vitro. Fifty volunteers were subjected to the intake of the herbal extracts by taking twice a day for 60 days. As a result, the treated subjects lost 3 kg of body weight and 3.5 kg of body fat mass after the treatment. Furthermore, the body mass index and waist size were significantly decreased during the experimental period. Above results suggested that the administration of the dietary additives composed of cinnamon and natural herbal extract improves the obesity by the decrement of body weight and body fat mass.

• Archives of Pharmacal Research
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• 제28권8호
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• pp.977-982
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• 2005

The aim of this study was to compare two formulations of film-coated pellets containing c1arithromycin after single oral dose study in healthy male volunteers. Two formulations with different coating polymers were prepared: formulation-1 (F-1) was prepared by incorporating three kinds of pH-dependent gradient-release coated pellets into capsules and formulation-2 (F-2) was prepared by coated with an insoluble semiosmotic film. Release profiles of filmcoated pellets were evaluated using paddle method under different conditions. Pharmacokinetic profiles of these formulations were obtained in three healthy male volunteers and compared to commercially available immediate release (IR) tablets. The relative bioavailability based on the $AUC_{0-24h}$ was found to be $96.2\%\;and\;58.7\%$ for F-1 and F-2 compared with IR, and the $T_{max}$ was delayed.

• Earthquakes and Structures
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• 제21권5호
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• pp.445-460
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• 2021

This study experimentally explored the behaviour of 12 concrete filled steel tube (CFST) and steel tube columns subjected to lateral cyclic loading. The L/D ratio was 12.3 while D/t ratios were 45.4, 37.8 and 32.4, classifying these 12 specimens into 3 groups. Each group included 3 CFST and 1 steel tube columns and were tested to failure. The experimental results indicated that CFST specimens reached the state of 'collapse prevention' (drift 4%) prior to the occurrence of local buckling. Strength degradation of CFST specimens did not occur up to the failure by buckling. This showed the favourable characteristic of CFST columns in preventing collapse of structures subjected to earthquakes. The high energy absorption capability in the post collapse limit state was appropriate for dissipating energy in structures. Compared to steel tube columns, CFST columns delayed local buckling and prevented inward buckling. Consequently, CFST columns exhibited their outstanding seismic performance in terms of the increased ultimate resistance, capacity to sustain 2-3 additional load cycles and significantly higher drift. A simple and reasonably accurate model was proposed to predict the ultimate strength of CFST columns under lateral cyclic loading.

• Journal of Pharmaceutical Investigation
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• 제33권3호
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• pp.171-178
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• 2003

Drug interactions with food, on occasion, lead to serious nutritional and functional changes in the body as well as alterations of pharmacological effect. It, therefore, should be necessary to take drug interactions with food into consideration for effective and safe therapeutics. Diabetes mellitus is a heterogeneous group of disorders characterzed by abnormal glucose homeostasis, resulting in hyperglycemia, and is associated with increased risk of microvascular, macrovascular, and neuropathic complications. However, the precise mechanism of diabetes mellitus remains unclear. Three basic objectives in the care of diabetic patients are maintaining optimal nutrition, avoiding hypo- or hyperglycemia and preventing complications. Laminaria japonica is a brown macroalgae which can be used as a functional diet due to high content of diatery fiber. The purpose of this study was to investigate the effect of Laminaria japonica diet on the pharmacokinetics of metformin which are frequently used in the treatment of diabetes. Diabetic rats induced by streptozotocin were employed in this study. Blood concentrations of oral hypoglycemic agent, metformin, were measured by HPLC and resultant pharmacokinetic parameters were calculated by RSTRIP. The mechanisms of drug interaction with food were evaluated on the basis of pharmacokinetic parameters such as $k_{a},\;t_{1/2},\;C_{max},\;t_{max}$, and AUC. Administration of metformin in normal and diabetic rats treated with Laminaria japonica diet showed significant decrease in AUC, $C_{max},\;and\;k_a$, and increase in $t_{max}$, compared to those with normal diet. This might result from adsortion of metformin on components of Laminaria japonica, causing delayed absorption. The oral glucose test showed that Laminaria japonica diet could lower blood glucose level probably through either inhibiting the activity of disaccharidases, intestinal digestive enzymes, or delaying the absorption of glucose. More studies should be followed to fully understand pharmacokinetic changes of metformin caused by long-term Laminaria japonica diet.

• 한국수산과학회지
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• 제31권5호
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• pp.677-684
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• 1998

Oxolinic acid (OA)를 경구 (80 mg/kg body weight)와 약욕 (20mg/$\ell$)의 방법으로 각기 다른 생리적 상태에 있는 나일 틸라피아 (Oreochromis niloticus)에 투여한 후 어류의 각 장기 내에 분포하는 OA의 농도를 bioassay 법으로 분석함으로써 어류의 생리적 상태가 OA 흡수, 분포 및 배설에 미치는 영향을 조사하였다. 사육수의 온도를 $15^{\circ}C$ 와 $25^{\circ}C$로 한 실험구에 OA를 경구로 투여한 후 약물의 흡수와 배설을 비교해 보면, $15^{\circ}C$ 실험구에서의 약물 흡수와 배설속도는 $25^{\circ}C$ 실험구보다 느렸지만 각장기 내 최고농도는 $25^{\circ}C$ 실험구와 유의성 있는 차이를 보이지 않았다. 그러나 OA를 약욕법으로 투여하는 경우 흡수 및 배설속도 모두 온도차에 의한 명확한 차이를 보여 주었다. 약물투여의 실질적인 목표가 되는 병어에서의 약물분포를 분석하기 위하여 E. tarda에 인위감염된 어류에 OA를 경구와 약욕의 방법으로 투여하였을 때 각조직 내의 약물 분포 및 농도의 변화는 건강어에 대비하여 구별됨을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제24권6호
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• pp.42-49
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• 2020

본 논문은 시멘트계 재료의 표면 및 구체에 소수성을 부여하여 내구성을 향상시키기 위한 기초연구이다. 실란/실록산계 혼합형 발수제를 첨가한 시멘트 모르타르를 제조하고 초기 수화성능 및 유동성능, 재령별 압축강도를 측정하였다. 또한 표면연마 전후의 물접촉각 및 흡수율을 측정하였다. 실란/실록산계 혼합형 발수제를 첨가한 시멘트 모르타르의 플로우는 발수제 첨가량 1.5%까지는 감소하는 것으로 나타났으며 첨가량 3.0%에서는 증가하였다. 실란/실록산계 혼합형 발수제를 첨가할 경우 시멘트 페이스트의 응결시간은 초결 및 종결 모두 지연되는 것으로 나타났다. 압축강도는 발수제의 최대 첨가량 3.0%에서 최대 30%까지 감소하는 것으로 나타났다. 실란/실록산계 발수제를 시멘트 모르타르에 첨가할 경우 접촉각은 커지는 것으로 나타났으며, 표면연마 후 접촉각은 표면연마 전보다 커지는 것으로 나타났다. 실란/실록산계 혼합형 발수제의 첨가는 표면뿐만 아니라 연마로 인하여 손상된 표면과 단면에서도 소수성을 나타내었다. 실란/실록산계 혼합형 발수제를 시멘트 모르타르에 첨가할 경우 흡수율은 낮아지는 것으로 나타났으며, 표면연마 후 흡수율은 표면연마 전보다 커지는 것으로 나타났다.

• 대한토목학회논문집
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• 제34권6호
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• pp.1677-1685
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• 2014

섬유를 콘크리트의 보강재로 소량 혼입한 섬유 보강 콘크리트는 콘크리트의 인장저항 능력과 연성능력을 향상시킬 수 있다. 최근에는 강섬유의 적용성이 확대됨에 따라 강섬유 길이의 연장을 통해 보강의 효과를 증대시키고 있다. 섬유의 길이 연장은 동일한 시공성과 품질성을 위해 섬유 혼입률을 동시에 감소시킬 필요가 있다. 따라서, 본 연구에서는 35mm, 60mm 길이의 강섬유와 화학적인 안정성과 내구성, 경제성 등이 우수한 보강 재료로 평가되어지고 있는 폴리프로필렌 섬유에 대해 섬유혼입률 1.0% 이하에서의 휨 성능을 평가하였다. 강섬유 혼입률이 0.25% 이상, 폴리프로필렌 섬유는 혼입률 0.5% 이상에서 균열강도 도달 후 취성 파괴되는 무보강보의 파괴거동을 개선하는 효과가 나타났다. 다만, 폴리프로필렌 섬유가 혼입된 보강 콘크리트는 균열 이후 deflection-softening 거동을 보였다. 그러나, 0.5%이상의 폴리프로필렌이 혼입된 보강보는 균열 이후 최대강도가 균열강도의 약 60~80%정도 강도회복을 보였으며, 강섬유에 비해 균열 이후 응력감소현상을 지연시키는 경향이 뛰어난 것으로 판단된다. 결론적으로 폴리프로필렌 보강콘크리트는 0.75% 혼입률 이상에서는 충분히 만족할 만한 구조적 휨 성능 향상을 보일 수 있을 것으로 판단된다. 특히, 폴리프로필렌 1.0% 보강 콘크리트의 에너지 흡수 성능은 0.5%, 0.75%가 혼입된 강섬유 보강 콘크리트의 에너지 흡수성능과 거의 비슷한 것으로 평가되었다.