• 농촌계획
• /
• 제12권3호
• /
• pp.19-28
• /
• 2006

This study has been conducted to perform the survey on the ecological systems, scenary, and water quality change for agriculturally purposed drainage channels constructed with the application of environment-friendly methods and thus to evaluate the environment-friendly redevelopment effects of them. The main results of this study are as follow: 1. The channels not looking good aesthetically before redevelopment had changed into graceful scenic views from the aspect of landscape architecture as natural-type gently waterside to the channel and naturally-looking water stream. In the village parks developed for the rest of residents, an enough view was secured and thus a wide prospect scope could be obtained. 2. The flora in the channels have increased to 35 families and 82 species from 19 families and 32 species before renovation. As the growth speed of them are slower than externally-brought plants, they can cause some risks to the stability of land slope, including scour by erosion. From that reason, it is necessary to adequately combine the species of the plants both natively growing there and externally-brought planted. 3. In case of water quality, it turned out that, from more than a year after redevelopment, plants began to take roots and the water quality improved. On the contrary, there have been some cases, partly found, that aggravated the quality of water due to the causes like as retention of floating matters by withered plants or plant bodies after the growth of plants in the channels under survey became active, and therefore it is judged that a periodic maintenance of waterways is needed. 4. In case of fishes, all species before renovation have revived, and the population and the number of species have increased after works the formation of puddles in the channels. In waterside grasslands, amphibia and reptiles have not only increased but also been diversified.

• 한국농공학회논문집
• /
• 제57권2호
• /
• pp.75-83
• /
• 2015

This study was aimed to estimate the total application cost and utilization of Turf grass VFS application through the field experiment. The experimental plots were constructed in an upland field of Iksan city within the Saemangeum watershed. Turf grass was transplanted at the down-slope edge of the pollution source area in each of the treated plots. Three rainfall events were monitored during the experiment period, and the rainfall-runoff relationships and NPS pollution reduction effects of the VFS systems were assessed. As results, the reduction ratio of runoff volume ranged 14.1~64.0 %, while the NPS pollution reduction ratio ranged 9.8~73.9 % for SS, 24.0~84.2 % for T-N, 31.6~80.9 % for T-P respectively. The total cost of VFS application was estimated by considering purchase cost of Turf grass sods and construction and maintenance costs of VFS system as well as the loss caused by giving up crop cultivation for the area needed to construct the VFS. The total cost of the VFS was estimated to be approximately \3,379,000/ha/year for the first year of application, and this cost could be decreased to \1,899,000/ha/year from the second year as the construction cost of VFS could no longer need to be counted afterwards. Apart from the NPS pollution reduction effects, the possible utilization of VFS was examined by detaching Turf grass within 40 % of VFS area for sale during spring time when the VFS systems fully covered. The benefit of selling the detached Turf grass sods was estimated as \1,260,000/ha/year, and also found that the VFS area successfully recovered by the time of the summer period. This benefit could attract farmers to adopt the VFS technique to manage agricultural NPS pollution.

• 한국산림과학회지
• /
• 제101권4호
• /
• pp.558-566
• /
• 2012

이 연구는 채석장의 실태조사를 통하여 토석채취 후 합리적이고도 완벽한 복구를 실시하기 위한 기초 자료를 제공하기 위하여 전국의 18개 토석채취장을 대상으로 조사한 결과는 다음과 같다. 농어촌정비사업에 따른 토석 채취 후 산지복구지는 대부분 조경적 녹화가 이루어지고 있다. 또한 복구공사 후 유지관리가 이루어지지 않아 식재한 나무가 고사하거나 비탈면녹화가 제대로 되지 않아 여름철에는 강우에 의한 표층토양의 유실 및 붕괴로 이어지고, 복구녹화공사를 실시한 비탈면은 황폐화되고 있는 실정이다. 따라서 자연친화적이고 완벽한 복구녹화공사를 실시하기 위해서는 비탈면녹화를 실시하기 전에 현장의 토질특성, 지질특성 등에 대해서 조사하고 그곳에 적합한 복구공법에 대하여 면밀히 검토해야 한다. 아울러 계획된 복구공법의 적용에 있어서도 복구비를 절감할 수 있는 공법의 적용이 필요하다. 조사 결과 토석채취지의 경우 토질이 토사질 또는 리핑암, 풍화토가 대부분으로 이러한 지역은 복구녹화가 완벽하게 이루어질 수 있는 조건이 되므로 여기에 적용하는 공법도 가능하면 간단하면서도 복구녹화가 충분히 될 수 있는 공법의 선정이 중요하다. 아울러 복구녹화계획 및 검토시에는 반드시 산지복구를 전공으로 하는 전문가의 의견을 청취함으로써 그 지역에 가장 적합한 복구녹화공법의 선정 및 완벽한 복구녹화가 가능하게 될 것으로 사료된다.

• 대한토목학회논문집
• /
• 제35권2호
• /
• pp.515-524
• /
• 2015

최근 궤도 접속부에서의 부등침하 및 궤도틀림으로 잦은 유지보수 및 열차운영에 지장을 초래하는 경우가 많아지고 있다. 이는 주로 궤도 접속부 시공에 사용되는 다양한 성토재료의 강우나 동결융해 같은 환경적 인자에 의한 역학적 물성들의 변화에 기인한 것으로, 본 연구에서는 궤도 접속부 성토재료에 대한 함수특성곡선을 산정하고 강우 시 포화도 변화 추이를 알아보고자 침투해석을 수행 하였다. 필터페이퍼를 이용하여 다짐 성토의 함수특성곡선을 성공적으로 산정할 수 있었고, 함수특성곡선 데이터를 이용한 강우 시 침투해석을 수행한 결과 궤도 접속부 성토재료의 포화도 분포는 강우강도, 뒤채움재 경사, 성토 및 절토 여부, 그리고 함수특성곡선에 큰 영향을 받는 것을 확인 하였다.

• The Korean Journal of Physiology and Pharmacology
• /
• 제20권1호
• /
• pp.111-117
• /
• 2016

Vagal nerve activity has been known to play a crucial role in the induction and maintenance of atrial fibrillation (AF). However, it is unclear how the distribution and concentration of local acetylcholine (ACh) promotes AF. In this study, we investigated the effect of the spatial distribution and concentration of ACh on fibrillation patterns in an in silico human atrial model. A human atrial action potential model with an ACh-dependent $K^+$ current ($I_{KAch}$) was used to examine the effect of vagal activation. A simulation of cardiac wave dynamics was performed in a realistic 3D model of the atrium. A model of the ganglionated plexus (GP) and nerve was developed based on the "octopus hypothesis". The pattern of cardiac wave dynamics was examined by applying vagal activation to the GP areas or randomly. AF inducibility in the octopus hypothesis-based GP and nerve model was tested. The effect of the ACh concentration level was also examined. In the single cell simulation, an increase in the ACh concentration shortened $APD_{90}$ and increased the maximal slope of the restitution curve. In the 3D simulation, a random distribution of vagal activation promoted wavebreaks while ACh secretion limited to the GP areas did not induce a noticeable change in wave dynamics. The octopus hypothesis-based model of the GP and nerve exhibited AF inducibility at higher ACh concentrations. In conclusion, a 3D in silico model of the GP and parasympathetic nerve based on the octopus model exhibited higher AF inducibility with higher ACh concentrations.

• 터널과지하공간
• /
• 제15권5호
• /
• pp.359-368
• /
• 2005

NATM 터널을 굴착하기에 토피가 너무 낮은 경우에는 보통 개착터널공법이 적용된다. 그러나 토피가 매우 낮거나 없는 계곡부에서 개착터널을 시공하기 위해서는 추가적인 두 곳의 갱구 형성과 복토가 이루어질 때까지 임시 사면에 대한 유지관리가 필요하다. 이런 경우에는 복토를 통해 토피를 확보한 후 터널을 굴착하는 방안이 유효하다. 이 연구는 터널 굴착이전에 소일시멘트로 복토한 후 굴착작업이 이루어진 대만고속철도 C240현장에 대한 사례 연구이다. 소일시멘트의 포틀랜드 시멘트 함유량은 $2\~4\%$이고, 1회 복토층의 두께는 $130\~250\;mm$ 범위가 되도록 시공하였다. 터널 굴착에 따른 소일시멘트 사면 및 터널내 최종 구조물인 콘크리트 라이닝에 대한 수치해석을 통해 안정성을 평가하였다.

• Journal of Biosystems Engineering
• /
• 제42권2호
• /
• pp.75-79
• /
• 2017

The use of tractors to carry out agricultural work has played an important role in mechanizing the agricultural sector. A repairable mechanical system (such as an agricultural tractor) is subject to deterioration or failure. In this study, a regression model was used to predict the failure rate of a John Deere 3140 tractor. The machine failure pattern was carefully studied, and key factors affecting the failure rate were identified in five regions of the Khouzestan province. Through a questionnaire, data was obtained from farm records. This data was grouped into six sub-groups, according to the annual use hours (AUH) and the manner in which the tractors were stored. Results showed that AUH and storage policies affected failure rate slightly. With an increase in the age of the tractors, the failure rate in the tractors used for 1050-2000 hours annually and stored outdoors was higher than those used for 200-1000 hours annually and stored in sheds. When the tractors were of the same age, the slope of the curve in the 200-1000 annual use hours increased gradually and then rapidly, but failure rate in the 1050-2000 annual use hours was high from the beginning, and subsequent increase in this value was almost uniform. As a result, it can be said that with an increase in the annual use hours, the failure and breakdown rate in John Deere 3140 tractors rapidly increases, but maintenance conditions only slightly affect the failure and breakdown rate.

• 한국측량학회지
• /
• 제21권4호
• /
• pp.393-401
• /
• 2003

해상파일 항타 공사를 위한 자동제어 기술은 해상에서 파일을 설계 도서상의 위치 좌표에 신속하고 정확하게 시방기준의 기울기와 방위로 항타 관입하여 시공품질 달성 및 시공 유지관리의 편리함을 제공할 수 있다. 따라서 본 연구에서는 해상 파일 항타를 위한 위치 자동제어에 RTK GPS 측량기법으로 정밀시공을 요구하는 파일을 이용한 해상구조물에 적용하여 해상준설공사, 파일 시설물 등의 해상 정밀시공관리 분야에 적용할 수 있는 3차원위치정확도를 결정함으로써 해상시공관리를 위한 보다 경제성 있는 RTK GPS 측량의 활용 방향을 제시하고자 하였다. 실시간 측정 정확도가 4cm 이내로 해상위치를 측정할 수 있으므로 시방기준에 비해 시공오차를 60% 감소시킬 수 있었고, GPS에 의한 해상 자동 위치제어 기술을 적용한 결과 해상공사 기간을 기존 공법 대비 30%를 단축하고, 해상공사 비용을 35% 절감할 수 있었다.

• 한국환경복원기술학회지
• /
• 제17권1호
• /
• pp.185-201
• /
• 2014

The Yong-neup of Mt. Daeam, which was designated as Korea's National Monument No.246 in 1973, is a high moor, and it has been managed with the designation as an ecosystem conservation area, Ramsar wetlands, and wetland conservation area. With the closing of the officially announced 5-year period for 'No-Trespassing' on the ecosystem conservation area starting August, 2010, it becomes necessary to arrange a systematic management and conservation scheme in consideration of the access & use of the visitors and Yong-neup's potential change into land consequent on making it open to the public. This study thinks that in order to preserve the Yong-neup, it's necessary to prepare the conservation plan for the program operation for exterminating exotic species, development of replacement wetlands and nurseries, access limit through zone categorization, establishment of environment-monitoring system, institutional management support, and establishment of managing facilities, etc., and to make scientific approaches, such as survey on wetland ecosystem, establishment of inventories, wetland monitoring, and drawing up of wetland ecology maps, etc. In addition, it is required that there should be adequate considerations of restoration of slope faces, drains, artificial embankment, water-collecting wells, roads for military operations, and wild-boar-stricken areas, etc., and should be continuous and systematic management of Yong-neup through the wise use of residents' participation-style maintenance, organization of a consultative body, introduction of CEPA programs, and introduction of visiting facilities and alternative transportation system, etc.

• 한국방재학회 논문집
• /
• 제8권1호
• /
• pp.63-69
• /
• 2008

연안 및 해양구조물에 대한 안전 및 유지관리는 해양환경과 그로인한 피해의 심각성으로 인해 매우 중요한 의미를 가진다. 이러한 구조물의 유지관리를 위해서는 구조물의 거동이나 변위감시 등의 활동이 이루어져야 하며, 최근 다양한 공간환경에 존재하는 대형 구조물의 유지관리나 거동감시를 위해 GPS, LiDAR, MBES, 자이로 등의 도구를 광범위하게 활용하고 있다. 현재 육상 구조물에서의 거동이나 변위감시등을 위한 다양한 장비와 방법론이 연구되고 있으나 일부 육상에서 감시가 가능한 해양 구조물을 제외한 수중에 존재하는 구조물에 대해서는 적용 가능한 방법론의 부족으로 어려움을 겪고 있다. 따라서 해양측량장비로 널리 사용되는 MBES 장비를 활용하여 수중 구조물 거동 및 환경감시의 일환으로 케이슨의 수중부 벽체에 대한 기울기를 조사 및 분석하여 수중 구조물 거동과 환경 감시의 가능성 여부를 분석하기 위한 기초 데이터로 활용하고자 한다.