• Korean Journal of Materials Research
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• v.4 no.5
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• pp.600-607
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• 1994

Optimum exper~mental conditions were established for the growth of heteroepitaxial GaAs layers on InP using liquid phase epitaxy (LPE) technique. Results showed that the optimum growth temperature was $720^{\circ}C$ at a cooling rate of $0.5^{\circ}C$/min. Surface morphology of the grown layers significantly improved by addition of about 0.005wt% Se to the Ga growth melt, which effectively suppressed melt-back of InP substrates into the melt during the initial stage of growth. It was observed that the quality of GaAs layers also improved substantially when the substrates patterned with grating structure were used, as determined by the (400) double crystal X-ray diffraction. The transmission electron microscopy observation indicated t.hat the misfit dislocations interact with each other at the grating region, resulting in a lower dislocation density in the upper GaAs layer.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.165-170
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• 2020

In this paper, it was confirmed that scopoletin inhibits neuroinflammation induced by amyloid beta oligomer (Aβ_1-42) in microglial BV-2. The mechanisms of inflammatory cytokines and inflammatory mediators by scopoletin were identified. Alzheimer's disease is the most common neurodegenerative disease, but it is a disease whose specific etiology is unknown, and many studies are trying to solve it. We first measured the cell viability with the CCK-8 assay method to confirm that scopoletin and Aβ_1-42 are toxic to BV-2 cells. Expression levels of interleukin 1 beta (IL-1β), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and nuclear factor-κB (NF-κB) in inflammatory reactions induced by Aβ_1-42 with western blot were analyzed. The ANOVA assay was used to compare protein expression differences between BV-2 cells treated with Aβ_1-42 alone and BV-2 cells pretreated with Aβ_1-42 and scopoletin. Therefore, this study suggested that scopoletin is worth developing as a neuroinflammatory protection agent for Alzheimer's disease in the future.

• Journal of Life Science
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• v.28 no.12
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• pp.1432-1437
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• 2018

Clara cell secretory protein (CCSP) plays an important role in protecting the lungs from inflammation. This research focuses on identifying the cis-element for binding the repressor of CCSP gene expression. A DNase I footprinting experiment revealed three protected regions between -812 and -768 bp (45 bp) of the mCCSP promoter. One motif (D3: GCCTGGGAA) was 100% conserved across rat, hamster, and human. The addition of excess amounts of the D3 motif exhibited high competition within that 45 bp range in an electrophoretic mobility shift assay. However, when mutated D3 ($G{\underline{AA}}TG{\underline{TT}}AA$) was used, the competition was significantly reduced. This demonstrates that the D3 motif within that 45 bp region of the mCCSP promoter is an important site for the protein-DNA interaction. Transient transfection assays with -756 Luc resulted in highly decreased expression of CCSP than those with -812 Luc, suggesting that the 45 bp could function as a binding site for the repressor. Co-transfection of KLF4 exhibited significant repression of the -812 Luc but not the -768 Luc which clearly shows that KLF4 might function as a repressor for the CCSP gene and also suggests that the D3 motif is strongly involved in the binding of KLF4. In addition, when anti-KLF4 antibody was added, super-shifted bands were observed. This result demonstrates that KLF4 could function as a repressor by binding to this 45 bp region of the CCSP promoter and that the D3 motif might be involved in the specific binding of KLF4.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.1
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• pp.75-84
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• 2021

In this study, we investigated inhibitory effect of Tripeptide against particulate matter (PM)-induced damage in human keratinocytes. PM-induced cell death was inhibited by Tripeptide and the activity of aryl hydrocarbon receptor (AhR) also inhibited by Tripeptide resulting in reduced expression of its downstream targets, cytochrome P450 family 1 subfamily A member 1 (CYP1A1) and cyclooxygenase-2 (COX-2), which are responsible for toxic metabolites production and inflammation. Furthermore, PM-induced expressions of pro-inflammatory cytokines, matrix metalloproteinase-1 (MMP-1) and apoptosis-related factors were decreased by anti-oxidant activity of Tripeptide. From these results, it has been shown that the Tripeptide has protective effect against PM-induced skin damage not only through the inhibiting of keratinocyte death but also through the inhibiting the secretion of several damage-inducing factors to adjacent skin tissue. And the results suggested that Tripeptide with anti-pollution effect could be applied as a new functional cosmetic material.

• Journal of Life Science
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• v.32 no.8
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• pp.647-658
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• 2022

Particulate matter (PM) is known to be involved in the onset and progression of various diseases by promoting oxidative and inflammatory reactions as air pollutants containing various small particles that are harmful. In this study, the protective efficacy of herbal medicines was evaluated in human corneal epithelial cells (hCECs) to select natural products that can protect the eye, the primary organ directly exposed to external pollutants from PM. As a result, five candid ate herbal medicines [Cheonmundong, Asparagus Rhizome; Seokchangpo, Aciru Gramineri Rhizoma; Hwangryeon, Coptidis Rhizoma; Gamgug, Chrysanthemi Indici Flos; and Geumjanhwa (Marigold flower petals)] which showed inhibitory efficacy on PM_2.5-induced cytotoxicity, were selected from among 12 candidate herbal medicines. To evaluate the antioxidant activity of these candidate substances, the reactive oxygen species (ROS) scavenging ability was investigated, and it was found that the extracts of Seokchangpo, Cheonmundong and Hwangryeon showed a significant inhibitory effect on PM_2.5-induced ROS production, which was correlated with the preservation of mitochondrial activity. In addition, it was confirmed that they could block DNA damage caused by PM_2.5 through analysis of 8-hydroxy-2'-deoxyguanosine generation and phosphorylated-H2A histone family member X (γ- H2AX) expression. Furthermore, the increase in inflammasome activity and inflammatory response in PM_2.5-treated hCECs was also canceled in the presence of these extracts. Although additional studies are needed, the results of this study will be used as primary data to find novel natural compounds that protect hCECs from PM.

• Journal of Life Science
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• v.32 no.10
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• pp.771-777
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• 2022

Dopaminergic (DA) cell death in Parkinson's disease (PD) has been attributed to multiple, distinct genetic and environmental factors. In rare familial PD loss of parkin function mutations play a key role in nigral DA neuron-specific pathogenesis primarily via endoplasmic reticulum (ER) stress. In more prevalent sporadic PD, environmental exposure to pesticides has a significant epidemiological role. However, it is largely unknown how environmental exposure to xenobiotics is etiologically linked with the known etiology in familial PD. In the present study biochemical evidence for a common pathogenic mechanism between sporadic and familial PD has been identified employing the recently characterized mesencephalic DA cell line, N27-A. Dieldrin, an organochlorine pesticide epidemiologically implicated in sporadic PD, induced the markers of ER stress response such as a chaperone BiP/Grp78, heme oxygenase-1 and especially, parkin. Accordingly, dieldrin activated the ER resident Caspase-12, a mediator of ER stress-specific apoptosis, during cell death of N27-A cells. Of great interest the dieldrin-induced DA neuronal cell death was synergistically rescued by the overexpression of ER resident neuroprotective proteins, parkin and Bcl-2. The present findings implicate that accumulation of ER stress could be one of common pathogenic mechanisms in idiopathic and familial PD, and some ER proteins, such as parkin and Bcl-2 may effectively attenuate ER stress-mediated N27-A DA cell death.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.39 no.9
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• pp.41-51
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• 2010

건물의 배수 및 통기시스템에서 나타나는 현상중에 확실한 내용이 아직 밝혀지지 않은 부분이 몇 가지 남아 있다. 이것은 19세기 말엽의 근대 위생공학의 시작 단계에서부터 잘 알려진 사실이다. 건물의 배수 및 통기시스템 운용에 대한 내용은 일반 공학과 특정 유체역학의 범위 내에서 가장 잘 이해할 수 있다. 건물의 배수 및 통기시스템의 운영에 종사했던 초기의 기술진들은 이러한 점을 잘 알고 있었으며 유체역학에 적합하게 응용한 많은 사례를 확인할 수 있었다. 제2차 세계대전이 끝나고 이에 대한 많은 연구가 진행되어 왔으며 특히 유럽에서 시작된 전후 재건 붐을 통해 배수 및 통기시스템의 설계에 좀 더 효율적인 접근이 진척되게 되었다. 이러한 배수시스템의 중심에는 배수관 내부의 오염된 공기가 배수구 또는 위생기구를 통하여 주거 공간으로 유입되는 것을 방지하는 트랩(Water Trap)이 있다. 배수트랩의 주요 기능인 봉수는 일반적으로 깊이가 40 mm에서 50 mm 정도로 위생기구의 종류에 따라 봉수의 깊이는 다소 차이가 있다. 배수관내 공기의 흐름이 중요한 것처럼 트랩의 봉수 메커니즘이 중요하기 때문에 이 메커니즘을 소홀히 여긴다면 안전한 배수시스템의 운영을 기대하기는 어렵다. 배수관 내의 공기의 흐름은 배수에 의해 유입되거나 또는 배출된다. 배수관에서 내부 압력의 불규칙한 변화로 인하여 야기되는 불안정한 배수의 흐름은 트랩의 봉수를 파괴하고 나아가 주거공간으로 오염된 공기가 새어 나갈 수 있는 통로를 제공하게 된다. 관내압력의 천이는 이로 인한 문제가 발생할 가능성이 있는 위치에 그 압력을 완화할 수 있는 장치를 설계단계에 반영하여 적용함으로써 제어할 수 있다. 건물 내부에 상당한 길이의 통기배관을 설치하는 것은 배관의 마찰손실로 인하여 천이 현상을 효과적으로 제어할 수 있는 확실한 방법이 되지는 못한다. 그렇지만 통기밸브를 설치하는 것과 같이 배수관 내로 공기를 공급해주는 유입구를 건물 내부에 분산 설치하는 것이 효율적인 통기방식이 될 수 있고, 정압 천이로 인한 위험을 줄여줄 수 있다. 통기밸브는 정압 발생의 원인이 되지 않으며 단지 정압에 반응하여 더욱 기밀하게 닫히며, 약화된 압력파를 반사할 뿐이다. 고층 건물에서 배수입상관과 평행하게 설치된 통기입상관(Parallel Vent Pipe)의 경우 극히 일부분의 정압 천이 현상을 완화할 수 있다. (통기 배관의 직경이 배수 입상배관과 동일한 경우 대략 1/3 정도임), 그러므로 정압의 천이로 인한 압력 파동은 배수 시스템의 나머지 부분을 통해 전파되어 배수 트랩에 영향을 미치게 된다. 정압의 천이가 예상되는 위치에 정압천이 완화 장치(Positive Air Pressure Transient Alleviation Device)를 사용하면 배관 내부압력의 급격한 상승을 방지하여 연결된 트랩의 봉수를 보호할 수 있다. 이렇게 되면 순간적으로 발생하는 배관내 압력의 급등 현상을 90% 정도까지 완화 시킬 수 있다. 경험적으로 배수시스템에서 배관이 완전하게 막혀 과도한 정압이 발생하는 경우는 거의 없다. 이러한 경우에는 가장 낮은 위치에 있는 배수 트랩의 봉수가 깨지면서 자연스럽게 배수시스템의 압력이 해소되게 된다. 이러한 사례는 통기 방식과 상관없이 발생할 수 있다. 실제와 유사한 시뮬레이션을 통하여 통기 밸브(Air Admittance Valves)는 전면 통기 시스템 (Fully Vented System)에서 최소한 트랩의 봉수 보호용으로 적합한 것이 확인 되었다. 어떤 경우 에는 고층 건물에 더욱 적합하다는 것을 확인할 수 있었다. 부압 해소용으로 통기밸브를 이용하고 정압완화용으로 정압 완화장치(PAPAs: Positive Air Pressure Transient Attenuators)를 사용하는 전면적 능동 제어시스템(Fully Engineered Designed Active Control System)이 사용자에게 육안으로는 확인하지 못하는 기능을 보장하면서 배수 시스템의 안전과 효율성에 대한 효과적인 방법을 제공하고 있다.

• Journal of the Korean Applied Science and Technology
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• v.40 no.5
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• pp.965-976
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• 2023

Reynoutria japonica is a perennate plant belonging to Polygonaceae and grows wild in East Asia containing Korea. Roots of Reynoutria japonica (R. japonica), part of roots of Reynoutria japonica, has been used for anti-inflammation and antispasmodics and contains emodin as active compound. Epidermis of skin is crucial roles to defense our body against stimulants, harmful substance and prevent water loss. In this study, we examined the effect of R. japonica and emodin, its active compound, on skin-barrier and moisturizing on HaCaT cells. First, antioxidant effect of R. japonica was prominent by scavenging ABTS⁺ radicals. Next, we conducted real time PCR and expression of filaggrin mRNA which is crucial role in differentiation of keratinocyte increased by R. japonica and emodin dose-dependently. In addition, R. japonica and emodin significantly elevated the expression of HAS-2 mRNA which play a role in hyaluronic acid synthesis on HaCaT cells. Taken together, R. japonica containing emodin, as active compound has potential as a cosmetic material for enhancing the function of skin-barrier and moisturizing in epidermis.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.664-669
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• 2010

The forest area of domestic is 6370304 ha, which covers 70% of the whole country, and especially Gangwon-do is remarkably larger than other Province. A thick forest of the country has the most basic component among other natural environments as well as it has invaluable worth to human being such as scientific research and educational value. However due to the breakout of forest fire since 1990s, the loss of trees, destruction of natural environment and ecology, economic damage have been occurring and its scale also has become larger. The causes of becoming larger in scale are resulted from forest components which mainly consist of needle leaf trees, wide leaf trees, fallen leaves, herbaceous plants so that it has been a direct cause for forest fire. However, few research on combustion and pyrolysis characteristics has been done in domestic and abroad. The study on the combustion and pyrolysis for Pinus densiflora which are typical needle leaf trees has been tried using TGA. Pinus desiflora started to being ignited at around $162^{\circ}C$ and pyrolysis was done at around $197^{\circ}C$. Differential method was applied to calculate activation energy and frequency factor according to the variation of conversion. Activation energy in pyrolysis was increased from 79 kJ/mol to 487 kJ/mol with increasing conversion and average activation energy was 195 kJ/mol. The activation energy in combustion was decreased from 148 kJ/mol to 133 kJ/mol.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.77-77
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• 2013

최근의 산업활동에서는 신규 원료 개발과 생산 효율성을 높이기 위하여 분체 공정이 증가하고 있는데, 미세 분진의 취급으로 분진운의 형성과 착화가 용이해지므로 분진폭발이나 화재 위험성이 증가하고 있다. 분진을 안전하게 사용하고 저장, 취급하기 위해서는 착화 전의 위험성 지표로서 최저발화온도(MIT ; Minimum Ignition Temperature)를 사전에 파악해 두는 것이 중요하다. 분진농도의 발화온도는 장치 내의 발화위험성이나 분진 취급 공정의 사고예방대책 관리를 위한 실용적 관점에서 중요하게 활용되는 폭발특성값이다. 또한 분진의 발화온도는 분진농도에 의존하며 농도변화에 따른 가장 낮은 온도를 MIT라고 한다. 본 연구에서는 화재폭발사고 빈도가 줄지 않고 있는 Mg 및 Mg-Al합금(60:40 wt%, 50:50 wt%, 40:60 wt%)을 대상으로 조성비율에 따른 최저발화온도를 실험적으로 조사하였다. Mg 및 Mg-Al(60:40 wt%), Mg-Al(50:50 wt%), Mg-Al(40:60 wt%) 시료의 평균입경은 142, 160, 151, $152{\mu}m$이다. MIT실험장치는 IEC 61241-2-1(Methods for Determining the Minimum Ignition Temperatures of Dust, 1994)에 준거하여 제작하여 사용하였다. 실험장치는 가열로, 분진운 시료홀더, 온도조절장치, 압축공기 제어장치 등으로 구성되어 있다. 구체적인 실험방법은 시험분진를 분진홀더에 장착하고 0.5 bar의 압축공기를 0.3 sec 동안 사용하여 일정 온도로 가열된 로의 내부로 분진운을 부유시킬 때에 분진운이 발화하여 가열로 하단부의 개방구에까지 화염이 전파하는지를 디지털비데오카메라로 기록, 평가하여 발화 유무를 판정하였다. Mg합금에 대한 MIT를 측정한 결과 $740^{\circ}C$가 얻어졌으며, Mg-Al(60:40 wt%)의 MIT는 $820^{\circ}C$로 조사되었다. 그러나 Mg-Al(50:50 wt%) 및 Mg-Al(40:60 wt%)에 대해서는 최대 가열로의 설정온도를 $890^{\circ}C$까지로 하여 농도를 변화시키면서 조사하였으나 발화가 일어나지 않았다. 문헌에 따르면 Mg입자 표면의 산화피막은 다공성으로 일정 온도에서 산화반응이 시간에 따라 직선적으로 증가하는데 반하여, Al의 산화피막은 보호 작용을 하여 일정 온도에서 산화반응속도가 표면과 내부의 농도 기울기에 의한 확산속도에 의존한다고 보고하고 있다. 본 연구결과를 토대로 Mg-Al합금의 발화특성을 고찰해 보면, Mg-Al합금에서 자기 전파성이 작은 Al성분의 증가는 착화지연이 증가하여 연소성이 감소하여 최저발화온도의 증가로 이어지는 것으로 추정되었다. 또한 발화온도는 주어진 조건의 온도장에서 분진이 존재하는 시간 길이에 따라 변화하므로, 발화온도를 실험적으로 측정하는 경우에는 측정장치나 방법에 따라 달라지므로 사업장의 현장에 발화온도를 적용하는 경우에는 장치 내의 분진의 존재시간을 고려할 필요가 있다.