도로에서 발생하는 대기오염의 주요 원인은 자동차 등의 연료연소로 인해 발생하는 미세먼지(PM), 질소산화물(NOX), 황산화물(SOX), 암모니아(NH3), 오존(O3) 등이며, 특히 미세먼지와 질소산화물은 도로를 이용하는 운전자와 보행자의 건강에 부정적인 영향을 미치는 것으로 알려져 있다. 본 연구에서는 버스정류장에 설치되는 미세먼지 저감시설의 미세먼지 저감효과를 분석하기 위하여 미세먼지 저 감능력을 실증할 수 있는 실대형 미세먼지 실증인프라와 실규모의 버스정류장을 이용하였다. 미세먼지 실증인프라에서 미세먼지 저감 시설이 설치되는 실험군(2곳)과 미설치되는 대조군(1곳)을 대상으로 미세먼지(PM10) 발생농도를 측정하였으며, 미세먼지 저감시설의 미 세먼지 저감효과를 분석하기 위하여 미세먼지(PM10)의 발생확률과 확률밀도함수를 산정할 수 있는 통계학적 방법인 Anderson-Darling 테스트(AD 테스트)를 이용하여 분석하였다. 미세먼지 저감시설의 미세먼지 저감효과는 대기질지수(AQI)의 기준을 준용하여 실험군ㆍ 대조군의 미세먼지 농도발생확률을 비교하여 정량적ㆍ정성적으로 분석하였다. 미세먼지(PM10) 농도발생확률 산정결과, AQI ‘보통’의 경우, 실험군 측정지점 1, 2와 대조군의 농도발생확률은 각각 77.24%, 63.26%, 0.00%로 대조군에 비해 실험군의 측정지점 1, 2에서 높 게 나타났으며, AQI ‘나쁨’의 경우, 실험군 측정지점 1, 2와 대조군의 농도발생확률은 각각 21.70%, 35.09%, 100.00%로 나타나 실험군 내의 미세먼지(PM10) 발생농도가 대조군과 비교해 개선되는 것으로 분석되었으며, 대조군 내부의 미세먼지 농도의 변화는 거의 없는 것으로 나타났다. 일반적으로 미세먼지를 측정하는 방식인 중량법과 베타선법을 통한 미세먼지 저감효과 분석방법은 시간당 평균으로 측정한 미세먼지 농도만 비교 가능하므로 정성적인 효과분석이 미비해 본 연구를 통해 소개한 통계학적 방법이 정량적 분석 뿐만 아 니라 정성적 분석에도 효과적일 것으로 기대하고 있다.

The purpose of this study is to present a plan for reducing noise between floors of apartment houses in Korea and to examine the method for evaluating noise blocking performance rating between floors. The definition of floor noise and classification method of floor noise can be described, and floor noise can be distinguished into lightweight impact sound and heavy impact sound. The wall-type structure, which is mainly adopted in domestic apartments, relatively transmits vibration caused by impact sources rather than using columns and beams, so noise problems between floors are relatively higher than systems using columns and beams. Three representative methods for reducing and blocking floor noise are described, and criteria for evaluating the effectiveness of floor noise reduction by each method are described. In addition, the method for noise reduction and blocking grades for each construction method currently applied in Korea was described, and as a result, it was judged that the domestic rating evaluation method was not suitable for the current domestic situation, and a new evaluation method and standard were needed.

본 논문에서는 신뢰성 기반 최적설계(RBDO)에서 성능함수의 비선형성을 고려한 효율적인 차원감소법(DRM)을 제안한다. 차원감 소법은 적분직교점과 가중치를 사용하여 1차 신뢰도법(FORM) 보다 더 정확하게 신뢰도를 평가하는 반면 성능함수를 추가로 해석해 야하기 때문에 적분직교점의 개수가 증가하면 효율성이 저해된다. 본 논문에서는 신뢰성 기반 최적설계에서 성능함수의 비선형도를 평가하고, 비선형도에 따라 적분직교점의 수를 결정하는 기준을 제안한다. 이를 통해 신뢰성 기반 최적설계가 진행될 때 반복마다 적 분직교점의 수를 조절하여 차원감소법의 정확도는 유지하면서 계산의 효율성은 개선하는 방안을 제안한다. 성능함수의 비선형도 평 가는 최대가능목표점(MPTP) 탐색에 사용한 벡터 사이의 각도를 통해 이루어지며, 수치 테스트를 통해 비선형도에 따른 적절한 적분 직교점의 수를 도출하였다. 2차원 수치예제를 통해 개발된 방법이 차원감소법이나 몬테카를로 시뮬레이션(MCS)의 정확도는 유지하 면서 효율성이 향상된다는 것을 확인하였다.

In this study, an experimental analysis of noise reduction in road traffic by applying the Micro Grooving technique to concrete highway pavements is explored. Initiated in 1984 to address the aging and damage issues observed in South Korea's concrete highways, Micro Grooving is known for creating fine grooves on the cement pavement surface to increase friction, prevent hydroplaning, and inhibit ice formation, while reducing vehicle friction noise by 3∼5dB(A). It is determined from noise measurement results that the application of the Micro Grooving method can be expected to reduce roadside noise and enhance the safety of drivers' driving experience.

본 논문에서는 자유도 기반 축소법과 부구조 기법을 적용한 반복 구조물의 효율적인 해석 기법을 소개한다. 기본 구조 반복된다는 특이성을 이용해 계산 방식을 개선하였다. 기본 구조를 하나의 부구조로 가정하고 IRS 기법을 통해 행렬을 축소하였고 부구조들의 결 합 위치에 따라 축소된 행렬을 배치하여 계산하였다. 이 과정에서 행렬의 크기가 크게 줄어들어 계산 시간이 감소하고 그와 동시에 해석에 필요한 메모리의 용량이 줄어든다. 행렬 축소에 Guyan 축소법이 아닌 IRS기법을 사용하였기 때문에 추가적인 반복 계산 작업없 이도 정확도가 유지된다. 개선된 방식은 수치 예제인 십자가 모양의 기본 구조를 통해 검증되었다.

The global trend is the application of heat-treated omission materials to reduce the manufacturing cost of automobile steering parts. Attempts have been made to apply heat-treated omission materials in domestic, but they are delayed due to concerns over rising cold forging process costs. For quantitative prediction of cold forging process cost, fatigue properties of forging die materials were evaluated. Based on this, the die life and cost were predicted quantitatively, and the manufacturing cost reduction of automobile steering parts using heat-treated material was found to be about 11%. Also, various methods to improve die life were additionally presented.

PURPOSES : The purpose of this study is to estimate the reduction of traffic noise in a double-layered specific porous pavement based on the traffic speed variation. METHODS : The close-proximity method was used in noise measurement, and the running speed was measured at 10 km/h and from 50 to 80 km/h. RESULTS : From the quantitative analysis, it was found that the double-layered porous pavement reduced by 9.4 dB (A) on the average and 9.16 dB (A) at a 95% confidence level. CONCLUSIONS : The use of porous pavements have been recommended to minimize traffic noise. In this study, it is quantitatively demonstrated that the double-layered porous pavement can reduce the traffic noise by more than 9.0 dB(A).

PURPOSES: Nitrogen oxide (NOx) is a particulate matter precursor, which is a harmful gas contributing to air pollution and causes acid rain. The approaching methods for NOx removal from the air are the focus of numerous researchers worldwide. Titanium dioxide (TiO2) and activated carbon are particularly useful materials for NOx removal. The mechanism of NOx elimination by using TiO2 requires sunlight for a photocatalytic reaction, while activated carbon absorbs the NOx particle into the pore itself after contact with the atmosphere. The mixing method of these two materials with concrete, coating, and penetration methods on the surface is an alternative method for NOx removal. However, this mixing method is not as efficient as the coating and penetration methods because the TiO2 and the activated carbon inside the concrete cannot come in contact with sunlight and air, respectively. Hence, the coating and penetration methods may be effective solutions for directly exposing these materials to the environment. However, the coating method requires surface pretreatment, such as milling, prior to securing contact, and this may not satisfy economic considerations. Therefore, this study aims to apply TiO2 and activated carbon on the concrete surface by using the penetration method. METHODS : Surface penetrants, namely silane siloxane and silicate, were used in this study. Photocatalyst TiO2 and adsorbent activated carbons were selected. TiO2 was formed by the crystal structures of anatase and rutile, while the activated carbons were plant- and coal-type materials. Each penetrant was mixed with each particulate matter reductant. The mixtures were sprayed on the concrete surface using concentration ratios of 8:2 and 9:1. A scanning electron microscopy with energy dispersive X-ray equipment was employed to measure the penetration depth of each specimen. The optimum concentration ratio was selected based on the penetration depth. RESULTS: TiO2 and activated carbon were penetrated within 1 mm from the concrete surface. This TiO2 distribution was acceptable because TiO2 and activated carbon locate to where they can directly come in contact with sunlight and air pollutant, respectively. Infiltration to the concrete surface was easily achieved because the concrete voids were bigger than the nanosized TiO2 and microsized activated carbon. The amount of penetration for each particulate matter reductant was measured from the concrete surface to a certain depth. CONCLUSIONS : The mass ratio on the surface can be predicted from the mass ratio of the particulate matter reductant measurement distributed through the penetration depth. The optimum mass ratio was also presented. Moreover, the mixtures of TiO2 with silane siloxane and activated carbon with silicate were recommended with an 8:2 concentration ratio.

An effective cleaning method for Ni removal in Ni-induced lateral crystallization(Ni-MILC) poly-Si TFTs and their electrical properties are investigated. The HCN cleaning method is effective for removal of Ni on the crystallized Si surface, while the nitric acid treatment results decrease by almost two orders of magnitude in the Ni concentration due to effective removal of diffused Ni mainly in the poly-Si grain boundary regions. Using the HCN cleaning method after the nitric acid treatment, re-adsorbed Ni on the Si surfaces is effectively removed by the formation of Ni-cyanide complexions. After the cleaning process, important electrical properties are improved, e.g., the leakage current density from 9.43 × 10−12 to 3.43 × 10−12 A and the subthreshold swing values from 1.37 to 0.67 mV/dec.

In recent years, there have been applied methods for minimizing noise by adjusting the method of installing soundproof walls, soundproof tunnels, soundproofing rims, environmental facilities, etc., and the shape of the surface texture of tire treads and packaging materials for the purpose of reducing road noise. Low noise pavement methods such as rubber asphalt (CRM), open graded asphalt concrete (OGAC), permeable Friction Courses (PFC), open graded friction courses (OGFC) and porous asphalt have been applied to reduce road noise. Especially, porous pavement is the most widely used low noise pavement with porous structure, which can reduce noise and drain water through continuous void of pavement. On the other hand, porous asphalt pavement has problems such as reduction of noise reduction effect and difficulty of road surface management due to void closing and increase of construction cost. The purpose of this study is to develop ultra-thin layer hot mix asphalt pavement method which maximizes road noise reduction effect by surface micro voids (Recover asphalt pavement) to improve void clogging of present porous pavement method. For this study, maximum size 5mm aggregate and cationic-treated fiber reinforced asphalt modifier (CSM) were used. The Marshall design method was applied grain-size distribution curve was based on SMA mix design. Marshall test, TSR, MMLS3 test and Hamburg test were carried out to evaluate the mechanical properties of ultra -thin layered asphalt pavement method with surface micro voids. Also, the effect of road noise reduction was evaluated through field application in urban area.

We studied the basic properties and fabrication of reduced graphene oxide (rGO) prepared using eco-friendly reduction agents in the graphene solution process. Hydrazine is generally used to reduce graphene oxide (GO), which results in polluting emissions as well as fixed nitrogen functional groups on different defects in the graphene sheets. To replace hydrazine, we developed eco-friendly reduction agents with similar or better reducing properties, and selected of them for further analysis. In this study, GO layers were produced from graphite flakes using a modified Hummer’s method, and rGO layers were reduced using hydrazine hydrate, L-ascorbic acid, and gluconic acid. We measured the particle sizes and the dispersion stabilities in the rGO dispersed solvents for the three agents and analyzed the structural, electrical, and optical properties of the rGO films. The results showed that the degree of reduction was in the order L-ascorbic acid ≥ hydrazine > glucose. GO reduced using L-ascorbic acid had a sheet resistance of 121 kΩ/sq, while that reduced using gluconic acid showed worse electrical properties than the other two reduction agents. Therefore, L-ascorbic acid is the most suitable eco-friendly reduction agent that can be substituted for hydrazine.

Biogenic amines (BAs) are toxic nitrogenous compounds and formed by the microbial decarboxylation of amino acids during fermentation. Consumption of fermented foods high in BAs can pose the adverse health effects. The objective of current study was to develop a reduction method of BAs in fermented soybean paste by applying catechins during fermented koji manufacturing step. Analysis of BAs in fermented soybean paste was conducted using High Performance Liquid Chromatography (HPLC). The levels of Putrescine decreased for 63.7%, 60.1%, 76.1%, 73.4% for 0.3% addition of Epicatechin, Epicatechin gallate, Epigallocatechin, Epigallocatechin gallate, respectively. The levels of Cadaverine decreased for 24.3%, 34.3%, 42.6%, 37.2% for 0.3% addition of Epicatechin, Epicatechin gallate, Epigallocatechin, Epigallocatechin gallate, respectively. Especially, The best reduction effect of BAs appeared for 0.3% addition of Epigallocatechin. Current study demonstrated the potential use of catechins for reduction of biogenic amines in fermented soybean paste model. Finding from this research can practically guide fermented food industry by providing practical application of additives for reduction of BAs.

Copper nanoparticles attract much attention as substitutes of noble metals such as silver and can help reduce the manufacturing cost of electronic products due to their lower cost and good conductivity. In the present work, the chemical reduction is examined to optimize the synthesis of nano-sized copper particles from copper sulfate. Sodium borohydride and ascorbic acid are used as reducing and antioxidant agents, respectively. Polyethylene glycol (PEG) is used as a size-control and capping agent. An appropriate dose of PEG inhibits the abnormal growth of copper nanoparticles, maintaining chemical stability. The addition of ascorbic acid prevents the oxidation of nanoparticles during synthesis and storage. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate the size of the synthesized nanoparticles and the coordination between copper nanoparticles and PEG. For chemical reduction, copper nanoparticles less than 100 nm in size without oxidized layers are successfully obtained by the present method.

미국 AASHTO LRFD(AASHTO, 2012)나 국내의 도로교설계기준(2012)의 차랑충돌에 대한 교각설계기준을 참조하면 교각 설계 시 차량충돌에 대해 정적인 하중을 고려하도록 제시하고 있다. 한편 2003년 미국 네브래스카 주에 트럭이 교각에 충돌하여 교각 및 교량 상부구조가 붕괴되는 사고가 발생하는 등 차량충돌에 의한 교량붕괴사고는 홍수에 의한 교량붕괴사고에 이은 두 번째 요인으로 분류되기도 한다. 화물차량의 대형화와 도로시스템의 개선으로 인하여 이러한 사고가 발생할 가능성이 중가하고 있다고 볼 수 있다. 본 연구에서는 교각 설계시 차량충돌에 대한 동적 해석을 수행하게 되면 많은 비용과 시간이 소요되어 실용적인 측면에서 연구결과가 쉽게 반영되지 못하고 있으므로 충돌해석 비용과 시간을 저감할 수 있는 모델축소법(model reduction)을 이용한 해석방법을 개발하였으며 그 효용성을 최종변위에 대해 직접충돌해석결과와 비교함으로써 평가하였다.

Spherical fine cobalt powders were fabricated by new liquid reduction method. Commercial cobalt sufate heptahydrate was used as raw material. Also ethylene glycol was used as solvent and hydrazine-sodium hypophosphite mixture was used as reduction agent for the new liquid reduction method. A plate shaped cobalt powders with an approximately 300 nm were prepared by a traditional wet ruduction method using distilled water as solvent and hydrazine. Spherical fine cobalt powders with an average size of 1-3 μm were synthesized by a new liquid reduction method in 0.3M cobalt sulfate and 1.5M hydrazine-0.6M sodium hypophosphite mixture at 333K.