• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.338-340
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• 2009

The asphalt pavement is usually non-uniform since achieving a non-segregated and homogeneous asphalt mixture is very difficult. The segregation can occur in the mixed material before it is fed onto the road and it become segregated as it is being placed onto the road surface. Note that this segregation determines the performance of the asphalt pavement. Hence, it is necessary to check the segregation by estimating the density of the asphalt pavement in the field. In this paper, a research on estimating the density of the asphalt mixture by measuring the dielectric constant of the material is conducted. An RF transceiver and an antenna are designed and tested to a series of asphalt density samples, and discussions are shown.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.277-282
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• 2006

Road traffic noise is not produced by any one factor rather occurs as a composition of various factors. Its occurrence is made by running engine noise, tire frictional, and exhaust noise etc. The quality of the noise depends on the size of the vehicles, rotation and engine speed, vehicle load, package state of the road and incline etc. The occurrence of noise level of heavy trucks appears louder than smaller vehicles and the noise levels produced differs according to speed and load etc between similar size vehicles. Other factors such as traffic density, average speed, mixing rate of heavy vehicles, and the distance between vehicles also generate road traffic noise. In this paper we examine 2, 4, and 6-lane roads in Jeonju. Consequently, this study examined the means used to measure road traffic noise. It was found that when there is a large traffic density and the average velocity is below 70 km/hr, the noise level could receive a relative proper value by the current measuring means. But in the case of night-time, it was found that the current measuring method is inapposite.

• 한국군사과학기술학회지
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• 제12권3호
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• pp.266-271
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• 2009

Electronic equipments and a missile carried by heavy trucks are often subjected to vibration and shock excitation during their transportation. Electronic equipments are so vulnerable to vibration and shock input that it is necessary to know in advance the vibration level of the truck which cause the damage of equipments. Road tests of a heavy truck carrying a canister on different road conditions such as paved road, unpaved road, and washboard are performed and the effect of road conditions on the vibration characteristics are analyzed. Vibration levels were measured at various locations of the truck along the path through which vibration was transmitted. This study reveals that the velocity of the truck as well as the road surface conditions are main factors which affect the vibration levels of the truck. The power spectrum density of the measured vibration signal and the factors affecting the PSD are also analyzed in this paper.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1836-1842
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• 2015

On road networks, the clustering of moving objects is important for traffic monitoring and routes recommendation. The existing schemes find out density route by considering the number of vehicles in a road segment. Since they don’t consider the features of each road segment such as width, length, and directions in a road network, the results are not correct in some real road networks. To overcome such problems, we propose a clustering method for congested routes discovering from the trajectories of moving objects on road networks. The proposed scheme can be divided into three steps. First, it divides each road network into segments with different width, length, and directions. Second, the congested road segments are detected through analyzing the trajectories of moving objects on the road network. The saturation degree of each road segment and the average moving speed of vehicles in a road segment are computed to detect the congested road segments. Finally, we compute the final congested routes by using a clustering scheme. The experimental results showed that the proposed scheme can efficiently discover the congested routes in different directions of the roads.

• Wind and Structures
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• 제6권5호
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• pp.325-346
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• 2003

High-sided road vehicles are susceptible to a sharp-edged crosswind gust, which may cause vehicle accidents such as overturning, excessive sideslip, or exaggerated rotation. This paper thus investigates the dynamic behaviour and possible accidents of high-sided road vehicles entering a sharp-edged crosswind gust with road surface roughness and vehicle suspension included. The high-sided road vehicle is modelled as a combination of several rigid bodies connected by a series of springs and dampers in both vertical and lateral directions. The random roughness of road surface is generated from power spectral density functions for various road conditions. The empirical formulae derived from wind tunnel test results are employed to determine aerodynamic forces and moments acting on the vehicle. After the governing equations of motion are established, an extensive computation work is performed to examine the effects of road surface roughness and vehicle suspension on the dynamic behaviour and vehicle accidents. It is demonstrated that for the high-sided road vehicle and wind forces specified in the computation, the accident vehicle speed of the road vehicle running on the road of average condition is relatively smaller than that running on the road of very good condition for a given crosswind gust. The vehicle suspension system should be taken into consideration, and the accident vehicle speed becomes smaller if the vehicle suspension system has softer springs and lighter dampers.

• 한국환경복원기술학회지
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• 제1권1호
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• pp.18-27
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• 1998

To investigate the restoration progression on soil physical properties and vegetation at the surface of logging road affected by timber harvesting operation. This study was carried out at logging roads constructed from 1989 to 1994 in Mt. Baekwoon, Kwangyang, Chollanam-do. Judging from the analysis of soil hardness, there were significant changes in the depth of soil between 5 and 10cm. Soil hardness was recovered from the compacted condition to the natural forest condition after 9 years passed. Soil macroporous ratio (pF2.7) of topsoil was higher than that of deep soil. Soil moisture retention of topsoil was more improved than that of deep soil. From the view of soil bulk density, the necessary time for recovering to the undisturbed condition of forest soil was about 10 years in the logging road left. Soil physical properties such as soil bulk density and porous ratio were recovered as time passed. Improved soil physical properties promoted the plant recovery on the logging road surface. The dominant species on the logging roads were Comus kousa, Prunus sargentii as overstory species, Rubus crataegifolius, Lespedeza bicolor as understory species, and Saussurea gracilis, Pteridium aquilinum var. latiusculum as herbaceous species. The plant recovery of bank-slopes was faster than that of cut-slopes and road surface. In progress of year, average plant coverage were 70 to 90% in cut- and bank-slopes and 30 to 60% on the logging road, surface which was elapsed 9 years after logging road construction. Therefore, additional planting and seeding work could be effective to the soil condition and vegetation restoration.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.571-577
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• 2018

본 선회다짐기는 도로 현장에서 가장 많이 사용하는 다짐 롤러의 다짐 특성을 반영하기 위해 개발된 실내 다짐장비이다. 기존의 충격을 이용한 프록터 다짐과는 달리 압축력과 회전을 통한 전단력을 이용한 현장 롤러의 다짐특성을 모사하였다. 본 연구의 목적은 기존의 프록터 다짐과정에서 얻기 힘든 전단응력 및 다짐중의 밀도변화 특성 등을 선회다짐기를 이용하여 평가하고, 이를 도로설계에 반영할 수 있는 기초자료로 활용하는 것이다. 이러한 선회다짐기를 이용하여 도로 현장 및 지하매설물 시공 시 가장 많이 사용되는 모래 및 노상토의 다짐 특성을 분석 및 평가하였다. 선회다짐기를 이용한 다짐 특성은 기본적으로 선회다짐 횟수와 시편의 높이, 다짐밀도, 간극비, 포화도 및 전단응력이다. 선회다짐 횟수가 증가할수록 시편의 높이는 작아지고, 간극비는 작아지고, 다짐 밀도는 증가하고, 포화도는 증가하며, 전단응력은 커지는 경향을 보였다. 전단응력은 다짐 초기에 200kPa 수준에서 시작하여 선회다짐 횟수 50회 정도가 되면 대략 330-350 kPa 수준으로 증가하였다. 동일한 시편의 경우 함수비가 커짐에 따라 다짐 밀도, 포화도 및 전단응력이 증가하는 경향을 보였다. 선회다짐기를 이용한 다짐은 밀도 및 전단응력 등 도로 설계 시 필요한 물성을 측정할 수 있는 장점을 가지고 있어 이를 도로설계시 반영한다면 더 공학적인 도로설계를 할 수 있을 것이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.424-429
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• 2013

The trolley carrying the pod moves along by the airfield runway. The pod through the trolley are subjected to vibration arising from the ground state, the precision optical components in the pod can have a significant impact. The road tests were conducted by using the measurement pod to remove the risk for the project. The measurement pod was composed with the ACRA, sensors, battery. The accelerometers were attached to get the acceleration through the road condition. The PSD envelop was calculated by FFT from the acceleration. The driving safety was proven through comparing the measurement data and MIL-STD-810G specification.

• 한국산림과학회지
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• 제83권4호
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• pp.545-555
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• 1994

이 연구(硏究)는 벌채작업후(伐採作業後) 방치된 운재로의 조기식생회복(早期植生回復)을 위한 과학적(科學的)인 기초자료(基礎資料)를 제공할 목적(目的)으로 1989년(年)부터 1994년(年)까지 서울대학교(大學校) 농업생명과학대학(農業生命科學大學) 부속(附屬) 남부연습림(南部演習林) 백운산지구(白雲山地區) 제(第) 26 임반(林班), 제(第) 27 임반(林班)에 연차적(年次的)으로 개설(開設)된 운재로(運材路)를 대상(對象)으로 이 연구(硏究)를 수행하였다. 운재로(運材路) 노면(路面)의 토양교란(土壤攪亂)으로 인한 토양가밀도(土壤假密度)와 자연식생회복(自然植生回復)을 조사(調査) 분석(分析)한 결과(結果)는 다음과 같다. 운재로(運材路) 노면(路面)의 토양가밀도(土壤假密度)는 운재로 개설후 시간의 경과에 따라 자연임지(自然林地) 상태(狀態)로 회복(回復)되어 가는데 약 10년이 소요되며, 계산식(計算式)은 다음과 같다. $$Y_1=1.4195-0.0744{\cdot}X(R^2=0.91)$$, $$Y_2=1.4673-0.0688{\cdot}X(R^2=0.73)$$ (단, X : 경과년수, $Y_1$ : 토양 0~7.5cm의 가밀도, $Y_2$ : 토양 7.5~15cm의 가밀도) 수림대(樹林帶)를 조성(造成)하고 운재로(運材路)를 개설(開設)한 지역(地域)의 토양깊이별 가밀도(假密度)는 각각 $0.892g/cm^3$, $0.903g/cm^3$로 수림대를 조성하지 않은 운재로보다 약 20% 낮았다. 운재로(運材路) 절(切) 성토사면(盛土斜面), 노면(路面)에 침입하는 목본의 중요도(重要度)는 산딸기, 산벚나무, 참싸리 등의 순이었으며, 초본은 고사리, 새, 큰까치수영 등의 순이었다. 또한 운재로 폐쇄후 약 6년이 경과되었을 때 식생피복도(植生被覆度)는 절(切) 성토사면(盛土斜面)은 약 70%, 노면은 약 20%로 운재로의 폐쇄후 조기에 인공적(人工的)으로 식생회복(植生回復)을 도모하는 방안이 검토되어야 할 것으로 사료된다. 따라서 성숙임목수확(成熟林木收穫) 벌채지역(伐採地域)에서 운재로(運材路) 개설시(開設時)에는 수림대(樹林帶)를 조성하여야 하며, 운재로 사용이 완료된 후에는 녹화수목식재공사(綠化樹木植栽工事) 및 파종공사(播種工事)와 노면굴기작업(路面掘起作業) 등을 통하여 운재로(運材路) 노면(路面) 토양(土壤)의 조속(早速)한 회복(回復)과 식생피복녹화(植生被覆綠化)를 유도하여야 할 것이다.

• 한국조경학회지
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• 제35권6호
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• pp.37-47
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• 2008

Recently, reckless exploitation of land resources without much consideration for the environmental value of the land has been witnessed to accommodate the ever-increasing demands for regional development. Fragmentation due to land development is a major reason for the declining biodiversity in forest ecosystems. The purposes of this study were (1) to investigate the relationship between the factors of land development and forest fragmentation in 13 watersheds of a metropolitan area and (2) to suggest a forest management plan through the relationship. We carried out a factor analysis to determine explanatory axes of forest fragmentation, and then conducted a correlation analysis between the factor scores and the factor of land development, such as the rate of built-up areas, road density, number of built-up patches, and area of housing developments. The first explanatory axis represented stability of landscape highly related with the rate of the built-up area and road density. The second axis represented the level of fragment highly related with a number of built-up patches. Forest fragmentation patterns of the 13 watersheds were classified for the similarity in forest fragmentation. This study presents the forest management plans including distribution and level of land development and forest conservation.