• 한국도로학회논문집
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• 제15권6호
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• pp.1-9
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• 2013

PURPOSES : About 35% of air pollutant is occurred from road transport. NOx is the primary pollutant. Recently, the importance of NOx removal has arisen in the world. $TiO_2$ is very efficient for removing NOx by photocatalytic reaction. The mechanism of removing NOx is the reaction of photocatalysis and solar energy. Therefore, $TiO_2$ in concrete need to be contacted with solar radiation to be activated. In general, $TiO_2$ concrete are produced by substitute $TiO_2$ as a part of concrete binder. However, 90% of $TiO_2$ in the photocatalysis can not contacted with the pollutant in the air and solar radiation. Coating and penetration method are attempted as the alternative of mixing method in order to locate $TiO_2$ to the surface of structure. METHODS : The goal of this study was to attempt to locate $TiO_2$ to the surface of concrete, so we can use the concrete in pavement construction. The distribution of $TiO_2$ along the depth were confirmed by basing on the comparison of $TiO_2$ compare by using the EDAX(Energy Dispersive X-ray Spectroscopy). RESULTS : $TiO_2$ were distributed within 3mm from concrete surface. This distribution of $TiO_2$ is desirable, since the $TiO_2$ induce photocatalysis are located to where they can be contacted with the air pollutant and solar radiation. CONCLUSIONS : Nano size $TiO_2$ is easily penetration in the top 3mm of concrete surface. By the penetration $TiO_2$ concrete can be produced with the use of only 10% of $TiO_2$, by comparing the mixing types.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.204-207
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• 2003

This paper presents the electrical properties of PTFE (polytetrafluoroethylene) nozzle for circuit breaker. PTFE has been used widely as a nozzle material for circuit breaker. In the arcing environment in a circuit breaker, radiation is considered to be the major energy transport mechanism from the arc to the wall. The fraction of the radiation power is emitted out of the arc and reaches the nozzle wall, causing ablation at the surface and in the depth of the wall. The energy concentration in the material lead to the depolymerization and eventually lead to the generation of decomposed gas as well as some isolated carbon particles. The generation of the decomposed gas in the depth of the material causes inner explosion. The surface of nozzle becomes uneven. The flow of gas is not uniform due to the unevenness of the surface. Adding some fillers into PTFE is expected to be efficient for improving the endurability against radiation. In this experiment, three kinds of fillers that have endurance in the high temperature environment were added into PTFE. Dielectric constant, dissipation factor, electrical resistivity and dielectric strength of PTFE composites were investigated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.141-141
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• 2010

The effect of thermal anneal on the characteristics of structural properties and the enhancement of luminescence and photovoltaic (PV) characteristics of silicon-rich silicon-nitride films were investigated. By using an ultra high vacuum ion beam sputtering deposition, B-doped silicon-rich silicon-nitride (SRSN) thin films, with excess silicon content of 15 at. %, on P-doped (n-type) Si substrate was fabricated, sputtering a highly B doped Si wafer with a BN chip by N plasma. In order to examine the influence of thermal anneal, films were then annealed at different temperature up to $1100^{\circ}C$ under $N_2$ environment. Raman, X-ray diffraction, and X-ray photoemission spectroscopy did not show any reliable evidence of amorphous or crystalline Si clusters allowing us concluding that nearly no Si nano-cluster could be formed through the precipitation of excess Si from SRSN matrix during thermal anneal. Instead, results of Fourier transform infrared and X-ray photoemission spectroscopy clearly indicated that defective, amorphous Si-N matrix of films was changed to be well-ordered thanks to high temperature anneal. The measurement of spectral ellipsometry in UV-visible range was carried out and we found that the optical absorption edge of film was shifted to higher energy as the anneal temperature increased as the results of thermal anneal induced formation of $Si_3N_4$-like matrix. These are consistent with the observation that higher visible photoluminescence, which is likely due to the presence of Si-N bonds, from anneals at higher temperature. Based on these films, PV cells were fabricated by the formation of front/back metal electrodes. For all cells, typical I-V characteristic of p-n diode junction was observed. We also tried to measure PV properties using a solar-simulator and confirmed successful operation of PV devices. Carrier transport mechanism depending on anneal temperature and the implication of PV cells based on SRSN films were also discussed.

• 대한기계학회논문집A
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• 제35권2호
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• pp.143-148
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• 2011

정유 석유화학 플랜트에서 탑 상부의 부식은 현장에서 자주 발생되는 심각한 문제이다. 특히 정유 공정 탑 상부에는 황화수소, 염소 등의 부식 물질들로 인하여 그 피해 정도가 심각하다. 따라서 본 연구에서는 정유 공정 탑 상부의 부식 메커니즘을 분석하고, 부식률을 예측하는 모델을 개발하였다. 정유 공정 탑 상부의 부식 메커니즘을 분석한 결과, 부식에 가장 큰 영향을 미치는 네 가지 성분인 $H_2S$, $CO_2$, $H^+$, $Cl^-$을 고려하여 예측 모델을 개발하였다. 부식 메커니즘을 해석하는 데에 이동 현상 및 반응 공학의 관점으로 접근하여 모델을 개발 하였다. 또한 실제 정유공장에서 측정된 데이터들을 토대로 그 신뢰성을 검증하였다.

• Toxicological Research
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• 제30권4호
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• pp.267-276
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• 2014

Exposures to lead (Pb) are associated with neurological problems including psychiatric disorders and impaired learning and memory. Pb can be absorbed by iron transporters, which are up-regulated in hereditary hemochromatosis, an iron overload disorder in which increased iron deposition in various parenchymal organs promote metal-induced oxidative damage. While dysfunction in HFE (High Fe) gene is the major cause of hemochromatosis, the transport and toxicity of Pb in Hfe-related hemochromatosis are largely unknown. To elucidate the relationship between HFE gene dysfunction and Pb absorption, H67D knock-in Hfe-mutant and wild-type mice were given drinking water containing Pb 1.6 mg/ml ad libitum for 6 weeks and examined for behavioral phenotypes using the nestlet-shredding and marble-burying tests. Latency to nestlet-shredding in Pb-treated wild-type mice was prolonged compared with non-exposed wild-types (p < 0.001), whereas Pb exposure did not alter shredding latency in Hfe-mutant mice. In the marble-burying test, Hfe-mutant mice showed an increased number of marbles buried compared with wild-type mice (p = 0.002), indicating more repetitive behavior upon Hfe mutation. Importantly, Pb-exposed wild-type mice buried more marbles than non-exposed wild-types, whereas the number of marbles buried by Hfe-mutant mice did not change whether or not exposed to Pb. These results suggest that Hfe mutation could normalize Pb-induced behavioral alteration. To explore the mechanism of repetitive behavior caused by Pb, western blot analysis was conducted for proteins involved in brain dopamine metabolism. The levels of tyrosine hydroxylase and dopamine transporter increased upon Pb exposure in both genotypes, whereas Hfe-mutant mice displayed down-regulation of the dopamine transporter and dopamine D1 receptor with D2 receptor elevated. Taken together, our data support the idea that both Pb exposure and Hfe mutation increase repetitive behavior in mice and further suggest that these behavioral changes could be associated with altered dopaminergic neurotransmission, providing a therapeutic basis for psychiatric disorders caused by Pb toxicity.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제5권2호
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• pp.199-205
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• 2002

저자들은 반복되는 저혈당과 점차 진행하는 담즙정체를 보이는 3개월 된 여아에서 호르몬 검사와 뇌 자기공명영상으로 뇌하수체 기능저하증을 진단하고 이에 대한 갑상선호르몬과 부신피질호르몬 치료 후 담즙정체가 호전되는 것을 경험하였기에 이를 보고하는 바이다.

• 생명과학회지
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• 제22권3호
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• pp.293-297
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• 2012

분자 운동 단백질은 신경세포 내의 세포체에서 특정 목적지까지 소포를 이동시키는데 관여한다. 오징어의 거대 축삭은 간단한 제거조작으로 축삭을 분리 가능하기 때문에 신경세포내 물질이동기전 연구의 좋은 모텔로 활용 가능하다. 이전연구에서 오징어 거대축삭의 소포들은 미세소관을 따라 이동하는 키네신 항체에 의하여 운반됨이 확인되었다. 본 연구는 오징어 뇌에 존재하는 키네신들을 크로닝하고, 분리된 유전자의 분석을 행하기 위하여 키네신 운동 도메인에서 잘 보존된 아미노산 배열에 해당되는 영역에 DNA primer을 이용하여 새로운 6종류의 키네신을 분리하였다. 오징어의 키네신들과 생쥐의 키네신들의 motor 영역의 아미노산분석에서 보존된 영역이 존재하며, Maximum Parsimony (MP) 방법, Neighbor-Joining (NJ) 방법, Minimum Evolution (ME) 방법, 그리고 Maximum likelihood (ML) 방법을 기초로 한 계통분석에서 생쥐의 키네신과 높은 상동성을 나타내었으며, 또한 계통수에서도 높은 상관관계가 확인되었다.

• 인터넷정보학회논문지
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• 제13권4호
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• pp.95-102
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• 2012

차량 애드 혹 네트워크(VANETs)를 위한 응용들의 개발은 지능적 안전 운송시스템 제공이라는 매우 제한적인 명확한 목표를 가지고 있다. 공공의 안전을 위한 긴급경고 기술은 제한된 시간에 신속하고 효율적으로 경고 메세지를 전달하는 지능형 방송 기법을 필요로 하는 응용중의 하나이다. VANETs 방송 프로토콜 설계 시에 접근제어 계층에서 여러 노드들이 동시에 전송을 시도할 경우, 다수 패킷들의 충돌과 여분의 지연을 발생하는 방송폭풍 문제가 고려되어야 한다. 본 논문에서는, 효율적으로 방송폭풍 문제와 시간 한계를 해결할 수 있는 조기 지능형 경보 방송(EI-CAST) 알고리즘을 제안한다. 제안 알고리즘은 충돌시간(TTC)에 기초한 조기경보 기술과 퍼지논리에 기초한 지능형 방송 기술을 사용하며, 시뮬레이션을 통해 제안 알고리즘과 기존 경보방송 알고리즘의 성능을 비교 평가 하였다. 실험결과 제안 알고리즘의 경우 경보 전송거리 4 km 이내의 차량들은 사고발생 이전에 경보메시지를 수신할 수 있으며 패킷 충돌이 없음을 확인할 수 있었다.

• 접착 및 계면
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• 제22권4호
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• pp.144-152
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• 2021

유기반도체와 게이트 절연체 간 계면전하이동을 이해하는 것은 고성능 유기메모리, 고안정성 유기전계효과 트랜지스터 (이하 유기트랜지스터) 개발에 기여할 수 있다. 본 연구에서는 계면 간 전하이동의 특이거동, 즉 홀전하가 유기반도체에서 고분자절연체로 이동되어 편재화되는 것이 편재화 준위간의 커플링에 의해 비선형적으로 가속화될 수 있음을 최초로 밝혀내었다. 이의 규명을 위해 rubrene 단결정과 Mylar 절연체를 기반으로 한 유기트랜지스터를 vacuum lamination 공정으로 제작하여 반도체-절연체 계면의 반복적인 전사와 박리에도 안정적인 소자를 개발하였다. Rubrene 단결정과 Mylar film의 표면을 각각 광유도 산소 확산법과 UV-오존 처리를 통해 결함을 생성시켰다. 그 결과, 계면 간 전하이동과 이에 의한 바이어스 스트레스 효과가 rubrene과 Mylar가 가진 편재화 준위 간 커플링에 의해 비선형적으로 급격하게 가속화되었음을 관측하였다. 특히, rubrene 단결정에 있는 적은 밀도의 편재화 준위가 계면 간 전하이동을 촉진하는데 가교역할을 함을 밝혀내었다

• 한국환경보건학회지
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• 제47권5호
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• pp.446-453
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• 2021

Background: Plastic particles less than 5 mm in diameter (microplastics) are well-known for causing various toxicities such as lung inflammation, oxidative stress, genotoxicity, and reproductive toxicity. As microplastics become smaller, they can move across cell membranes, the placenta, and the blood-brain barrier. Objectives: We evaluated the toxicities of polyethylene microplastics (PE-PMs) in dams and neonates through intragastric intubation of pregnant ICR mice. Methods: Low concentrations (0.01 mg/mouse/day) and high concentrations (0.1 mg/mouse/day) of polyethylene microplastics were administered from the ninth day of pregnancy to postnatal day seven. The control group was administered with distilled water. On the day of sacrifice, the weight of dams and neonates and the organ weight of neonates was measured. Further, acetylcholinesterase levels and glutathione peroxidase levels were evaluated by using a blood sample obtained on the sacrifice day. Results: No significant difference in the number of neonates was found, but the body weight gain of dams was seen to be lower in the low-dose group. On the other hand, we observed a consecutively declining trend in the weight gain and organ weight of neonates among the high-, control, and low-dose groups. Meanwhile, the serum acetylcholinesterase and glutathione peroxidase level were higher in the low-dose group compared to the control group. Further, the dose-dependent accumulation of microplastics in the organs of neonates revealed the transport of plastic particles from dams to their offspring. Conclusions: Although the exact mechanism of toxicity caused by microplastics could not be confirmed, it was validated that exposure to microplastics during pregnancy and lactation causes its migration between generations and accumulation throughout the body. Hence, it is necessary to evaluate the systemic toxicity of microplastics and assessment of co-morbidities such as second-generation toxicity, neurotoxicity, and depression following long-term exposure.