• 한국산학기술학회논문지
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• 제19권2호
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• pp.125-136
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• 2018

대설 재난은 한국에서 태풍 및 호우 다음으로 두 번째로 많은 자연 재해라고 할 수 있다. 대설 재난으로 인한 2005년에서 2014년 사이의 연 평균 경제 피해액은 약 80억원이다. 심각한 경제적 피해에도 불구하고 한국에서 대설 재난에 대한 경제 효과 연구는 거의 없다. 본 연구의 목적은 다중 회귀모형을 이용하여, 대설 재난의 경제적 피해액과 강설량, 강설일, 인구밀도, 비도시지역 비율 및 수도권 더미 변수 등 간의 연관성을 확인하는 것이다. 2005년부터 2014년 사이의 대설 재난 피해액 관련 데이터는 행정안전부 (국민안전처)에서 발행하는 자연 재해 연보를 이용하였으며, 강설량 및 강설일과 같은 날씨 관련 데이터는 기상청에서 수집하였다. 인구와 비도시 관련 데이터는 지자체 통계 데이터를 사용하였다. 연구 결과 강설일, 강설량, 비 도시면적 비율 등이 대설 재난 피해에 영향을 주는 것으로 나타났다. 본 연구의 결과는 한국의 대설 재난 관리 정책에 적용될 수 있다.

• 대한의생명과학회지
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• 제27권4호
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• pp.248-254
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• 2021

Ulcerative colitis (UC), chronic inflammatory bowel disease, is characterized by severe inflammation in the colon. Tea is one of the most popular beverages consumed worldwide. Pu-erh tea, a unique Chinese tea produced by microbial activities, possesses a broad range of health-promoting effects, including anti-aging, anti-Alzheimer's disease, antioxidation and anti-obesity. However, the inhibitory effect of Pu-erh tea on intestinal inflammation and the underlying mechanism remain unclear. The present study was designed to evaluate the regulatory effect of Pu-erh tea extract (PTE) on dextran sulfate sodium (DSS)-induced colitis clinical signs by analyzing the weight loss and colon length in mice. The inhibitory effects of PTE on inflammatory mediators, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α, and the activation of nuclear factor-κB (NF-κB) were also determined in DSS-treated colitis tissue. We observed that PTE treatment significantly inhibited the DSS-induced clinical symptoms of weight loss, decrease,in colon length, and colon tissue damage in mice. Moreover, PTE attenuated the DSS-induced levels of IL-6 and TNF-α in colon tissue. We also demonstrated the anti-inflammatory mechanism of PTE by suppressing the activation of NF-κB in DSS-treated colon tissues. Collectively, the findings provide experimental evidence that PTE may be effective in preventing and treatment of intestinal inflammatory disorders, including UC.

• 한국자원식물학회지
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• 제32권6호
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• pp.714-722
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• 2019

Oxidative DNA damage negatively affects humans and the research is currently ongoing to find ways to reduce oxidative stress. Oxidative stress has been identified as a key factor in triggering various diseases. Thus, its alleviation is important for human health. Broussonetia kazinoki (B. kazinoki) has been used in traditional Korean medicine as a dermatological therapy to treat burns, pruritus, and acne. B. kazinoki is generally segregated into peeled root (PR), root bark (RB), peeled stem (PS), and stem bark (SB). To assess these components for their antioxidant activity and protection against DNA damage, their ethyl acetate fractions were examined by 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assay. As a result of confirming the expression of factors involved in attenuating DNA damage, the protective effect of SB on oxidative stress suppressed the expression of p-p53 and γ-H2AX. Additionally, the levels of p53 and H2AX mRNA were significantly downregulated. In conclusion, these results indicated that the SB component of B. kazinoki had the potential to be used as an effective natural antioxidant compared to the other parts of the plant.

• Journal of Korean Neurosurgical Society
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• 제64권6호
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• pp.873-881
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• 2021

Objective : Peripheral nerve injuries occur mostly as a result of mechanical trauma. Due to the microvascular deterioration in peripheral nerve damage, it becomes challenging to remove free oxygen radicals. Gallic acid is a powerful antioxidant with anti-inflammatory effects and a free radical scavenger. The purpose of the study is to show that gallic acid contributes to the restorative effect in mechanical nerve damage, considering its antioxidant and anti-inflammatory effects. Methods : Thirty male Sprague Dawley albino mature rats were included in the study. Ten of them constituted the control group, 10 out of 20 rats for which sciatic nerve damage was caused, constituted the saline group, and 10 formed the gallic acid group. Post-treatment motor functions, histological, immunohistochemical, and biochemical parameters of the rats were evaluated. Results : Compared to the surgery+saline group, lower compound muscle action potential (CMAP) latency, higher CMAP amplitude, and higher inclined plane test values were found in the surgery+gallic acid group. Similarly, a higher nerve growth factor (NGF) percentage, a higher number of axons, and a lower percentage of fibrosis scores were observed in the surgery+gallic acid group. Finally, lower tissue malondialdehyde (MDA) and higher heat shock protein-70 (HSP-70) values were determined in the surgery+gallic acid group. Conclusion : Gallic acid positively affects peripheral nerve injury healing due to its anti-inflammatory and antioxidant effects. It has been thought that gallic acid can be used as a supportive treatment in peripheral nerve damage.

• 전기학회논문지P
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• 제58권3호
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• pp.257-262
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• 2009

Capacitor is basically used for the power-factor compensation and sometimes as the passive filter to reduce harmonics of nonlinear load. Since the impedance of capacitor is inversely proportional to the frequency. The harmonic current may result in the problems of voltage distortion and resonance. Capacitor has easily fall under by two harmonic components, a nonlinear load and a distorted utility voltage. The amplified harmonic current and voltage may damage power capacitor. Hence the pre-investigation of harmonic is needed before designing and application the power factor for reducing fault rate. In this paper, we analyzed that voltage and current with harmonics components act on the capacitor under the resonance condition. we concluded that both voltage and current harmonics have an bad effect on the capacitor and current harmonics is a bitter rather than effect by voltage harmonics.

• 한국식품영양과학회지
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• 제33권7호
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• pp.1133-1138
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• 2004

본 연구는 streptozotocin(STZ)을 투여하여 고혈당이 유발된 생쥐(UM군)에 생지황(Rhemanniae Radix) 전탕액의 투여(5.0 mL/kg/day, RR군)효과를 밝히기 위하여 수행하였다. STZ로 유발된 생쥐에 생지황 전탕액을 6주 동안 구강 투여한 후 혈당과 당내성 검사 및 췌장섬의 면역조직화학 검사를 하였다. 혈당수준은 RH군이 HM군에 비하여 2, 3, 5, 6주에서 유의성 있게 낮았으며, 당내성 검사 또한 RR군이 HM군에 비하여 우수한 결과를 보여 주었다. 6주 후 insulin-양성 5-세포들과 insulin-like growth factor-II 양성 물질들은 HM군에 비하여 RR군에서는 보다 높게 나타났다. HM군에서는 apoptosis 면역반응성 과립들이 췌장섬 전반에 걸쳐 관찰되었으나, RR군에서는 일부 세포들의 핵에서 면역반응성을 보여주었다. HM군에서는 대부분 췌장섬들이 파괴되어 소수 관찰되었으나 RR군은 다수 관찰되었다. 이와 같은 결과로 보아 생지황 전탕액은 STZ로 유발된 손상으로부터 췌장섬을 회복시키는 효과가 있는 것으로 사료된다.

• Environmental Analysis Health and Toxicology
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• 제21권3호
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• pp.229-238
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• 2006

Although, mercury (Hg) is not a naturally abundant element in the environment, residues frequently occur in many environmental compartments because of widespread contamination from industrial and agricultural practices. This research evaluated Hg-B concentrations of general population who was not occupationally exposed. And also evaluates the association between life factor and health effect with Hg-B concentration of general adult through interrelationship estimation and index about kidney function and oxidative damage that appeared by questionnaire survey and medical examination. Average concentration of Hg-B was 3.19 $\mu$g/L (ND$\sim$8.64 $\mu$g/L), and persons who exceed mercury exposure level (5 $\mu$g/L) presented in WHO (1990) appeared by 16 (7.0%). High-risk group (smoking and meat main intake group) had significantly higher Hg-B concentration than low-risk group (non-smoking and vegetable diet main intake group) (p < 0.05, low-risk group: 3.30 $\mu$g/L (ND$\sim$8.64 $\mu$g/L), high-risk group: 4.27 $\mu$g/L (ND$\sim$7.84 $\mu$g/L).

• 한국지반신소재학회논문집
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• 제9권4호
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• pp.75-84
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• 2010

본 연구에서는 띠형 섬유보강재의 인장특성, 크리프 변형, 내시공성 및 내구성을 평가하기 위한 일련의 장기성능 평가시험을 수행하였다. 또한 시험결과를 바탕으로 장기설계인장강도 산정을 위한 강도감소계수를 평가하였다. 먼저, 크리프 변형 특성을 평가하기 위해 단계 등온법과 시간-온도 중첩법을 이용하였으며, 크리프 감소계수는 1.6을 적용하는 것이 바람직한 것으로 평가되었다. 다음으로 입도 조정된 화강풍화토를 성토재로 사용하여 수행한 내시공성 시험 결과, 보강재의 강도특성에 영향을 미치는 원사의 손상이 거의 없는 것으로 확인되어, 장기설계인장강도에 큰 영향을 미치지 않을 것으로 분석되었다. 마지막으로 내구성 평가 결과, 내화학성, 내미생물 및 내후성을 고려한 강도감소계수는 1.1을 적용하는 것이 합리적인 것으로 평가되었다.

• 한국재료학회지
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• 제3권2호
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• pp.197-204
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• 1993

Plastic기 복합재료의 파괴거동에 미치는 원공크기오 판폭의 영향을 검토하기 위하여 단축인장시험을 행하였다. 점응력파손조건에서의 특성길이 $d_o$는 원공크기 및 판폭에 의존하며, 이를 기초로 파손강도를 예측하기 위한 수정 점응력 파손조건식을 제안하였다. 이 파손조건의 예측값은 실험값과 잘 일치하였다. 파손 강도는 원공선단의 손상비의 증가에 따라 증가하며, 이는 손상영역의 형성으로 인한 응력완화현상으로 설명되어 진다. 또한 불안정 파괴시의 최대균열길이 $a_c$는 특성길이 $d_o$의 약 2배의 값을 나타낸다. 파괴인성에 대응하는 한계에너지해방율 $G_c$의 변화는 원공선단의 손상영역의 증가에 의한 응력완화가 주요한 원인이라고 할 수 있다.

• 한국정밀공학회지
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• 제22권2호
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• pp.113-119
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• 2005

A crack emanating from an internal electrode or a conducting damage path in ferroelectric ceramic actuators is analyzed. The boundary of the domain switching zone near the edge of the internal electrode in a ceramic multilayer actuator is determined based on the nonlinear electric theory. The stress intensity factor induced by a ferroelectric domain switching under small scale conditions is numerically obtained for flaws of various sizes near the electrode edge. It is found that stress intensity factor near the crack tip depends on the material property of the electrical nonlinearity.