• 한국ITS학회 논문지
• /
• 제19권5호
• /
• pp.40-51
• /
• 2020

2011년에 고속도로 정체 기준 속도가 개정된 후 많은 시간이 경과함에 따라 차량의 성능 개선, 경쟁 관계에 있는 고속열차 운행 확대, 고속도로 일부 구간의 제한속도 상향 등 다양한 고속도로 주행환경 변화가 발생하였고 고속도로 이용자의 이동 신속성에 대한 기대수준 또한 증가하는 추세이다. 따라서 본 연구에서는 설문조사를 통해 고속도로 이용자의 정체에 대한 인식을 조사하고, 고속도로 교통류 분석을 통해 고속도로 정체 기준 속도의 재설정을 검토하고자 한다. 설문조사 결과, 고속도로 이용자들이 인식하는 정체 기준 속도가 다소 높아진 것을 확인하였다. K-means 알고리즘을 통해 교통량 및 속도 자료를 분석한 결과, 서행과 정체의 분류 기준은 60km/h 수준인 것으로 나타났다. 또한 정체 기준 속도를 50km/h와 60km/h로 상향하는 것을 가정하여 고속도로 정체잦은구간을 산정해본 결과, 50km/h가 고속도로 이동성 관리를 위한 정체 기준 속도로 적절한 것으로 판단된다.

• 공업화학
• /
• 제24권6호
• /
• pp.650-655
• /
• 2013

본 연구에서는 Pd/C 촉매를 이용하여 무수말레인산(maleic anhydride) 수용액상에서 수소화 반응을 통해 호박산(succinic acid) 합성을 진행하였으며, 그에 따른 최적 공정 조건을 도출하고자 하였다. 반응 온도 및 반응시간에 따른 호박산 순도의 차이는 크지 않았으나 압력과 교반속도가 증가함에 따라 불순물의 생성이 줄고, 호박산의 순도가 증가함을 확인하였다. 실험 결과 본 수소화 반응에서는 압력과 교반속도가 기체-액체 간 물질전달저항을 감소시켜 반응속도를 증가시킬 수 있는 가장 중요한 변수임을 확인하였으며 이에 따라 압력과 교반속도에 대한 반응속도를 구하였다. 반응압력이 5 bar에서 10 bar로 2배 증가 시, 반응속도는 2.14배 증가하였으며 교반속도가 300 rpm에서 700 rpm으로 2배 증가 시, 반응속도는 2.36배 증가함을 확인할 수 있었다.

• 농업과학연구
• /
• 제44권1호
• /
• pp.114-122
• /
• 2017

An experimental pick-up type pulse crop harvester was built and its harvesting performance for green kernel black bean was evaluated. Field bean loss and harvested bean quality of the harvester were analyzed according to engine speeds of 2,000; 2,400; 2,800; 3,000; and 3,200 rpm, and travel speeds of 0.6; 1.0; and 1.4 m/s. Operating conditions and field capacity of the harvester for proper harvesting were estimated. The harvester had an optimum performance at a grain moisture content of 13.4%, an engine speed of 3,000 rpm, and a travel speed of 1.2 - 1.3 m/s. Subsequently, the picking-up, discharging, and total bean loss ratios were found to be 1.6, 1.3, and 2.9%, respectively. The whole bean, damaged bean, unthreshed bean, and foreign material ratios were determined to be 96.2, 1.0, 0.1, and 0.3%, respectively. Results showed that the harvester had lower bean loss and higher harvested bean quality than those of imported bean combines. The harvester could harvest 2 rows with a crop spacing of an approximately 1.4 m. Its optimum travel speed was estimated to be approximately 1.2 m/s when harvesting performance was taken into account using such variables as field bean loss and harvested bean quality for green kernel black bean. Effective field capacity of the harvester was estimated at approximately 40 a/h.

• 한국기계가공학회지
• /
• 제12권2호
• /
• pp.27-33
• /
• 2013

In this study we analyzed the on-road driving performance of two parallel-type diesel-hybrid buses which have been driven in Daegu metropolitan area. A real-time on-board data logger was facilitated to measure the vehicle information such as vehicle speed, idle stop, state of charge of battery, and engine operating conditions. These diesel-hybrid buses ran as a commuter at Daegu Exco area and Dalsung industrial complex. The driving pattern in Exco area comprised more frequent idle stop and relatively lower speed than at Dalsung area, where comprised no idle stop. Due to those different driving patterns, the fuel economy at Dalsung showed $3.7\;km/{\ell}$, which is about 8% higher than that of Exco. The main causes of this come from the higher portion of regenerative braking and higher speed which moves to the operating points of diesel engine with a lower fuel consumption.

• 대한조선학회논문집
• /
• 제60권2호
• /
• pp.120-134
• /
• 2023

In this study, hydrodynamic characteristics of dam break flow were investigated by a series of experiments. The experiments were performed in a 2-D rectangular flume with obtaining instantaneous images of dam break flow to capture the free surface elevation, and pressure distributions on vertical wall and bottom of the flume. The initial water depth of the dam break flow was changed into 3 different heights, and the gate opening speed was changed during the experiments to study the effect of the gate speed in the dam break flow. Generation of dam break phenomena could be classified into three stages, i.e., very initial, relatively stable, and wall impact stages. The wall impact stage could be separated into 4 generation phases of wall impinge, run-up, overturning, and touchdown phases based on the deformation of the free surface. The free surface elevation were investigated with various initial water depth and compared with the analytic solutions by Ritter (1892). The pressures acting on the vertical wall and bottom were provided for the whole period of dam break flow varying the initial water depth and gate open speed. The measurement results of the dam break flow was compared with the hydrodynamic characteristics of green water phenomena, and it showed that the dam break flow could overestimate the green water loading based on the estimation suggested by Buchner (2002).

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2021년도 춘계학술대회
• /
• pp.592-593
• /
• 2021

지난해 7월, 대통령 주재 한국판 뉴딜 국민보고대회를 개최하여 그 핵심 전략으로 「한국판 뉴딜 종합계획」을 발표하였고, 교육 분야에서는 '그린스마트 미래학교' 사업이 한국판 뉴딜 10대 대표과제 중하나로 포함되었다. 그리고 작년 한해 COVID-19로 인한 비대면 수업 확산으로 일선 교육현장의 ICT기술의 요구가 빠르게 급증하였다. 따라서 본 논문에서는 과거 교실의 무선네트워크 및 유선 인프라의 문제점을 고찰하고 이후 비대면 수업 및 대면 수업시 사용가능한 초고속 무선네트워크를 보유한 그린 스마트 교실을 위한 유선네트워크 인프라와 무선 네트워크 장비들을 설계하고 실제 교실에 구축하기위한 예시를 제시하였다.

• 인간식물환경학회지
• /
• 제24권4호
• /
• pp.377-387
• /
• 2021

Background and objective: To improve air quality, particulate matter (PM) can be reduced using green infrastructure. Therefore, in this study, we aimed to determine the particulate matter reduction potential of climbing plants used for green walls, an element of vertical green infrastructure. Methods: A sealed chamber with controlled environmental variables was used to assess the PM reduction level caused by climbing plants. PM concentration in the plant chamber was measured after two and four hours of PM exposure, and the reduction potential was assessed based on the leaf area. Results: Compared to the empty chamber (Control), the PM reduction speed per hour was higher in the plant chamber, which confirmed that climbing plants contribute to the reduction of PM in the air. The PM reduction speed immediately after exposure in the plant chamber was high, but this slowed over time. Additionally, PM has been continuously reduced in plants with large leaves. As a result of calculating the particulate matter reduction level based on leaf area, it was found that there was a difference by particle size. Actinidia arguta, Parthenocissus tricuspidata, Trachelospermum asiaticum, and Euonymus fortunei var. radicans showed a high reduction effect. The trichomes on the leaf surface of Trachelospermum asiaticum were found to affect PM reduction. Conclusion: PM adsorption on the leaf surface is an important factor in reducing its concentration. It was possible to compare different plants by quantifying the amount of PM reduction during a fixed time period. These results can be used as the basic data to select the plant species suitable for urban green walls in terms of PM reduction.

• 한국안광학회지
• /
• 제20권3호
• /
• pp.369-375
• /
• 2015

목적: 본 연구에서는 종이책 독서 시 바탕색에 따른 읽기속도와 순목횟수의 변화를 측정하고 이들의 상관관계를 알아보고자 하였다. 방법: 본 연구목적에 동의하고 안질환 및 안과적 수술경험이 없으며, 양안시가 가능한 성인 29명(남10, 여19)의 대상에게 백색, 적색, 녹색 및 청색바탕에 검은색 글씨로 구성되어 있는 소설을 각각 15분 동안 읽게 하였다. 독서 시 장당 읽기속도와 순목횟수를 측정하고 각 바탕색 별로 분석하였다. 결과: 바탕색에 따른 장당 읽기속도는 백색과 녹색바탕에서는 독서시간이 경과함에 따라 빨라지는 경향을 보였으나, 청색바탕에서는 거의 변화가 없었으며, 적색바탕에서는 오히려 느려짐을 알 수 있었다. 반면, 장당 순목횟수는 모든 바탕색에서 독서시간이 경과함에 따라 감소하는 경향을 나타냈으나 적색바탕에서의 감소가 가장 적었다. 모든 바탕색에서 순목횟수가 감소할수록 읽기속도는 증가하는 상관관계를 보였으며, 녹색바탕의 경우 가장 높은 상관관계를 나타내었다. 결론: 본 연구결과 동일한 조절 및 폭주요구량을 가지는 거리에서의 독서 시 순목횟수가 감소할수록 읽기속도는 빨라지는 상관관계를 가짐을 확인하였으나 주 파장에 따라 순목횟수와 읽기속도의 변화는 달라짐을 알 수 있었다. 이는 근업 시 주 파장의 차이에 따라 작업의 속도와 시각피로도가 달라질 수 있음을 의미하므로 요구되는 인지의 종류에 따라 작업환경과 조건의 조정이 이루어져야 함을 제안할 수 있다.

• 한국환경과학회지
• /
• 제22권12호
• /
• pp.1599-1610
• /
• 2013

In order to verify the healing effect in the variety of effects according to fountain type, anion which is the representatives factor of healing, as the center of case studies which in Gwanghwamun(Ground fountain), Cheonggyecheon(Waterfall) and Myeongdong(Formative fountain). According to fountain type, the anion distribution as follow, figures typically$ 15,721{\pm}419ea/cm^3$, Formative fountain $40,190{\pm}788ea/cm^3$, Waterfall $4.480{\pm}290ea/cm^3$ and ground fountain $2.492{\pm}180ea/cm^3$. It is usually exceed to the distribution in natural green, which is $1070{\sim}2100ea/cm^3$. The interrelation between air temperature, relative humidity, wind speed and relative humidity, and wind speed is that, the relative humidity is directly proportional to wind speed and inversely proportional to temperature. As the temperature goes up, the distribution of anion goes down. And as the wind speed and relative humidity goes up, the distribution of anion decrease sharply. The result of interrelation between fountain type and the anion distribution is that, the distance of water falling is directly proportional to the anion distribution in the formative fountain and inversely proportional in the ground fountain. And the distribution of anion is largest in formative fountain. The distribution of anion in ground fountain is lower than in formative fountain, but it is far more than in natural greenery. And as the distance from fountain increase, the distribution of anion goes down.

• Journal of Biosystems Engineering
• /
• 제34권6호
• /
• pp.411-419
• /
• 2009

This study was carried out to develop a shredding-burying machine for application of gramineae green manure crops that were tall and had high biomass yield such as sudan grass and rye. We made a prototype to operate both shredding and burying concurrently to attach at middle-sized tractors. Field tests were performed with the prototype to treat rye and sudan grass. The test results showed that the average cutting length became shorter and the quantity of entwined stem became obviously decreased when the PTO shaft speed was fast and running speed was slow. Also, We found, when the cut stem length became shorter, the burying ratio became more increasing and the PTO power requirement became more decreasing. Working efficiency of the prototype was better than conventional Rotary. The test results for treating rye/sudan grass with prototype showed that average cutting length was 21.2/22.5 cm and burying ratio was 98.4/98.1% when the PTO shaft speed was 1,000/1,000 rpm and running speed was 0.25/0.17 m/s. Also, the working performance of the prototype was 0.79 and 1.14 h/10 a for rye and sudan grass, respectively. Finally, we found that the prototype of shredding-burying machine was better for labor than conventional method that required at least 3 times bigger tractor.