• 대한토목학회논문집
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• 제28권4D호
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• pp.493-504
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• 2008

현재 건설시장에서는 시공의 기계화 및 로봇화 촉진을 통하여 인력의존형으로부터 탈피하고자 하는 노력이 지속적으로 이어져 오고 있다. 본 연구에서는 건설생산의 효율성 제고를 위한 건설기계장비의 활용도 향상을 위해 국내 외 건설기계 자동화와 관련된 연구개발 동향을 살펴보고, R&D 투자현황을 조사 분석하였다. 또한 건축과 토목공사에 있어 건설자동화 분류체계를 수립하고, 자동화 대상작업의 후보군을 선정한 후 설문조사를 통하여 자동화 대상작업의 우선순위를 도출하였다. 도출된 자동화 우선순위를 바탕으로 총괄로드맵을 작성하였으며, 자동화 단위 그룹과 단위 그룹 내 자동화 대상작업의 자동화에 필수적으로 요구되는 요소기술의 도출결과를 바탕으로 중점영역별 로드맵을 구축하여 제시하였다. 본 연구의 결과물은 국내 건설 생산방식의 성력화 및 기술집약화를 위한 첨단 기술분야 R&D 전략수립의 기초자료로 활용될 수 있을 것으로 기대된다.

• Journal of Biosystems Engineering
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• 제29권5호
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• pp.419-424
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• 2004

In this study, a series of soil bin experiment was carried out to investigate experimentally the effect of the tire inflation pressure and axle load of tire on the steering torque for the off-road condition. The experiment was performed at the three levels of off-road conditions(ground I, ground II and ground III) and on-road condition(ground IV), four levels of tire inflation pressure(120 kPa, 170 kPa, 220 kPa and 270 kPa), and four levels of axle load(1470N, 1960N, 2450N and 2940N). The results of this study are summarized as follows: 1. Steering torque at the off-road conditions were higher than that on the on-road conditions for all levels of tire inflation pressure and axle load. 2. As the axle load increased, steering torque also increased f3r all experimental ground conditions. 3. For the axle load of 1470N the biggest steering torque was measured on the ground condition I, but as the axle load increased to the value of 2940N the biggest steering torque was measured on the ground condition III. From the above results, it was found that for the low axle load, steering torque gets higher on the soft ground condition, but for the high axle load, steering torque gets higher on hard ground condition for whole range of experimental conditions. 4. As the tire inflation pressure decreased, steering torque increased on the on-road condition, but no specific trend was not found at the off-road conditions.

• Journal of Biosystems Engineering
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• 제33권1호
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• pp.38-44
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• 2008

The freight vehicle is mostly used to transport the fruit. Shock and impact generated by the freight vehicle may give serious damage to fruits hence to reduce the fruits damage, the optimum packaging design during transportation by vehicle is required. In order to design the packaging system for fruit transportation optimally, the comprehension of characteristic for vibration and shock acting on vehicles under various road conditions and loading methods is required. This research was performed to analyze the shock characteristics, acceleration level and power spectral density (PSD) of the fruit transportation vehicles under several travel roads and positions. The vibration signal was measured and analyzed at the transportation vehicle operating on the road of three different surface conditions. The maximum acceleration was measured at the rear-end of the vehicle, and the acceleration in the direction of up-and-down (z-axis) was much greater than those in the directions of back-and-forth (x-axis) or right-and-left (y-axis). The peak acceleration in the direction of up-and-down (z-axis) at the vehicle driving on the expressway, the local road paved with concrete, and unpaved local road were 5.3621 G, 8.232 G, and 14.162 G respectively. PSD at 2.44 Hz showed maximum value at all road conditions. The maximum values of PSD on the expressway, a local road paved with concrete, and unpaved local road were 0.0075222 $G^2/Hz$, 0.058655 $G^2/Hz$, and 0.24598 $G^2/Hz$ respectively. The value of PSD decreased with an increase of the vibration frequency of the transportation vehicle. In most cases, the vibration frequency was below 20 Hz during transportation.

• 한국기후변화학회지
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• 제1권3호
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• pp.211-217
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• 2010

건설 장비, 항공 지상 지원 장비, 항만 하역 장비, 농림업 기계를 포함하는 비도로 수송 부문의 경우 IPCC Guidelines의 배출원 분류 코드에 비도로 수송(1A3e2)이 존재하나, 국내에서는 배출자료가 구축되지 못하고 있다. 본 연구에서는 건설업, 항공, 해운, 농림업에 해당하는 석유 통계 자료를 유종별로 구분하였고, 1996 및 2006 IPCC Guidelines에서 제시하는 배출 계수로 Tier 1 수준의 비도로 수송 부문 온실 가스 배출량을 산출하고 비교하였다. 그 결과, 1996 IPCC Guidelines과 2006 IPCC Guidelines에 의한 2007년 비도로 수송 온실 가스 배출량은 각각 4,919천ton $CO_2eq./yr$, 5,530천ton $CO_2eq./yr$으로 나타났다. 본 연구에서 추정한 비도로 수송 온실 가스 배출량은 국내 수송 부문 온실 가스 배출량의 약 5.5%에 해당하는 양으로 추정되었다.

• 한국대기환경학회지
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• 제25권3호
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• pp.188-195
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• 2009

Generally. mobile sources of air pollution were classified in on-road and non-road. Due to increased registration number of construction equipment in Korea. updated emission factors for non-road mobile sources, such as construction machinery. should be developed. NONROAD model of U.S. EPA already has introduced transient adjustment factors and sulfur adjustment factors for emission factors of diesel powered engine. In addition to this. European Environment Agency (EEA) has proposed emission factors for off-road machinery including several types of construction equipment. In this study. six types of construction equipment, such as excavator. forklift, loader, crane, roller and bulldozer, were studied to estimate emission factors based on total registration status in Korea. Total 445 construction equipments between 2004 and 2007 model year were tested with KC1-8 mode and air pollutants (CO, THC, $NO_x$, and PM) were measured. After statistical estimation and calculation, emission factors for CO, THC, $NO_x$, and PM for excavator, forklift, loader, crane, roller and bulldozer were provided and compared with previous emission factors. Moreover, updated emission factors for six types of construction equipment in this study were verified after comparison with emission factors of U.S. EPA. Finally, estimated emission amounts of four air pollutants were suggested according to six types of construction equipment.

• 대한기계학회논문집B
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• 제35권6호
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• pp.577-583
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• 2011

비도로 차량용 디젤엔진의 Tier 4 interim 규제를 만족하기 위하여 입자상물질과 질소산화물 배출량은 현행 규제 대비 각각 95%, 30% 저감되어야 하며, 입자상 물질을 저감하기위한 방법으로 디젤산화촉매, 부분유량 매연 여과장치 및 매연여과장치가 비도로 차량용 디젤엔진에 적용될 수 있다. 또한 질소산화물을 저감하기위해 배기가스 재순환방법, 선택적 환원촉매와 희박 질소산화물 포집장치 등이 적용될 수 있다. 본 연구에서는 56kW급 off-road 차량에서의 입자상물질과 질소산화물을 저감하기위해 매연여과장치와 고압루프 배기가스재순환 시스템이 연구되었다. 실험결과로서 디젤산화촉매와 매연여과장치는 입자상물질을 저감하는데 매우 효과적이었으며 낮은 배압과 함께 출력손실도 5%이내였다. 고압루프 배기가스재순환을 적용한 결과 중 저부하 조건에서 효과적으로 질소산화물을 저감하였으며 배기가스재순환율이 높을수록 질소산화물의 저감율도 증가하였다.

• 한국건설관리학회논문집
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• 제20권3호
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• pp.39-45
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• 2019

건설현장의 생산성은 견실성 및 생산활동의 효율성 평가을 위한 매우 중요한 지표이며, 건설 현장작업은 모두 작업조를 중심으로 수행됨으로 작업조의 생산성 관리는 특히 중요하다. 문헌연구 및 전문가 인터뷰를 통해 도출된 27개의 관리요인들로 설문조사를 실시하였으며 32부를 회수하여 분석하였다. 대분류항목의 실행도 및 중요도를 분석한 결과, '장비'와 '건설인력' 항목이 도로교량 공사의 작업조 생산성에 매우 중요한 것으로 나타났으며, 실행도는 중요도에 비해 비교적 미비한 것으로 밝혀졌다. 또한 소분류 항목 27개를 분석한 결과, 지속적인 관심을 가져야 하는 항목으로는 '적기의 장비조달', '효율적 작업조 구성', '작업자의 숙련도', '현장통제 및 감독능력'이 중요도에 비해 실행도가 낮음으로 보다 더 향상시킬 필요가 있는 관리 요인들로는 '장비 가동성능', '설계도서의 정확성', '시공상세도의 정확성', '작업지시 및 승인 시기', '작업지시의 정확성' 등인 것으로 밝혀졌다. 본 연구의 결과는 앞으로 도로공사의 구조체 공사에서 작업조 생산성 향상을 위해 유용하게 사용될 수 있을 것으로 사료된다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2001년도 동계 학술대회 논문집
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• pp.16-21
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• 2001

The ride quality of agricultural tractor seats is evaluated based on the vibration of the human bodies. Tractor ride vibration levels have been measured at the person-seat interface along 7 axes(3 translational axes at the feet, 3 translational axes on a seat surface and 1 axis at the seat back), under different operating conditions. Since one of the most important parameters for ride comfort is the level and duration of the root mean square acceleration experienced, the ride values, such as the seat effective amplitude transmissibility, the component ride value, and the overall ride value based on acceleration root mean square are evaluated for a conventional tractor using frequency weighting functions and axis multiplying factors. The ride indices are also studied considering to the variation of vehicle speed and road profile.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.449-455
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• 2009

A reversible axial flow fan called jet fan has been widely used for longitudinal ventilation in road tunnels to secure a safe and comfortable environment cost-effectively. As shifting the flow direction is usually made by only switching the rotational direction of an electric motor due to heavy duty, rotor blades having identical aerodynamic performance for bidirectional flow should be necessary. However, such aerodynamically desirable blades haven't been developed sufficiently, since most of the related studies have been done from the viewpoint of unidirectional flow. In the present paper, we demonstrate a method to profile the blade section suitable for bidirectional flow, which is validated by studying the aerodynamic performances of rotor blades of a two-stage jet fan experimentally and numerically.

• Journal of Biosystems Engineering
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• 제26권4호
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• pp.315-322
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• 2001

Agricultural products can be damaged due to the vibration of transporting trailer on the off-road. So, this study was conducted to identify the vibration characteristics of the agricultural products transporting trailer by measuring the vertical acceleration according to positions on the trailer loaded with agricultural products. The results of this study can be summarized as follows: 1. At non-operating state of engine, the larger vertical acceleration was occurred at rear side compared with front side in the case of 4.5Hz of vibration frequency. But, in the case of 53.5Hz of frequency, the maximum vertical acceleration at front side of trailer was higher than value at rear side. So, the maximum acceleration at front side of the trailer was increased with the increase in frequency. 2. At operating state of engine, the maximum vertical acceleration at front side of the trailer was increased with the increase in frequency. 2 At operating state of engine, the maximum vertical acceleration delivered through the hitch from the engine was occurred at front side of the trailer as $3.0\times10^{-3}m/s^2$, in the case of 8.75Hz of frequency. But, in the case of 102.5Hz of high frequency, the maximum vertical acceleration was occurred at rear side of the trailer. 3. When the power tiller loaded with pear of 325kg was travelling on the artificial uneven road of 3cm height, the maximum acceleration was occurred at rear side of the trailer as $4.7\times10^{-3}m/s^2$at 3.75Hz of frequency. But, that was occurred at diagonal of the trailer 43.5Hz and 91.25Hz, which meant that there was rolling and pitching on the trailer. 4. At operating state of engine, the mean acceleration of the trailer delivered through the hitch according to the increase in frequencies was showed the maximum value at range of 40-90Hz. At rear side of traiㅣer, the maximum value was occurred at about 40Hz, and that was reduced according to the increase in frequencies and diminished at about 100Hz. 5. When the power tiller loaded with pear of 32.5kg was travelling on the artificial uneven road of 3cm height, the mean acceleration by the increase in frequencies was showed lower level at rear side than front side of the trailer. This was opposite configuration to the Hinsch’s results tested with air-conditioned truck. This means that the shorter length of the trailer, the more effect of engine vibration is transferred to the front side of trailer.