• 한국안전학회지
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• 제27권1호
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• pp.117-122
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• 2012

In recent years, there have been a number of concerns and measures surrounding 'Traffic Safety' for children. But, actually, safety measurements of 'School Zone' lack. This research thesis was designed to quantify risk degrees of 'School Zone', in a simple way, with the development of evaluation indicators to evaluate risk degrees of 'School Zone'. This is deems to be used for a guideline necessary for devising improvements or safety measures against 'School Zone' in the future. And, this is expected to be useful for managing and controlling safety each local facility about elementary schools.

• Journal of Magnetics
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• 제16권4호
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• pp.444-448
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• 2011

In the present study, we separated the marker particles from the suspending particle mixture solution using isotacho-electrophoresis technique, a novel quantitative ionic particle separation method, in the microchannel. A multiple stacking zone of the suspending particle was visualized with variations in electric field strength, pH value and concentration of the ionic solution. In particular, the electrophoretic mobility of ionic particle (fluorescein) was estimated based on the electrophoretic velocity value measured by the particle image velocimetry. As a result, isotacho-electrophoresis zones were clearly visualized as going downstream in the electric field. The particle migration velocity increased proportional to the applied voltage increase; it was also affected by the pH value variations in the ionic solution.

• Restorative Dentistry and Endodontics
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• 제40권2호
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• pp.113-122
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• 2015

Objectives: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). Materials and Methods: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.39-48
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• 2021

Analysis of the change in water content and distribution was conducted according to the supply of recirculation water to a landfill. An excavation sample analysis showed that the recirculation water injection zone had water content 8.8% point higher than that of the non-injection zone, after 8 months of operation. And due to the influence of recirculation water supply by vertical wells in injection zones, the water content increases along with depth more clearly than non-injection zone. According to an electrical specific-resistivity survey after 13 months of operation, the water content got higher towards the bottom of the landfill. The water transmission coefficient is 8.72×10^-4 cm/sec for injection zones and 3.36×10^-5 cm/sec for the intermediate cover layer; analysis shows that the intermediate cover layer may affect the penetration velocity of water supplied by the horizontal injection tube. For the scientific design and operation of re-injection facilities, it was deemed necessary to follow-up research on the residence time and behavior of re-injection water considering the ratio of recirculation water supply in horizontal and vertical tubes, and pitcher coefficient of intermediate and waste layers.

• Steel and Composite Structures
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• 제38권2호
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• pp.223-239
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• 2021

This paper presents the analytical modeling and finite element (FE) analysis, using ABAQUS software, of the new types of steel reinforced lightweight aggregate concrete (SRLAC) columns with cross-shaped (+shaped and X-shaped) steel section, using proposed three analytical and two FE models in total. The stress-strain material models for different components in the columns, including the confined zones of the lightweight aggregate concrete (LWAC) using three and four concrete zones divisions approaches and with and without taking into account the stirrups reaction effect, are established first. The analytical models for determining the axial load-deformation behavior of the SRLAC columns are drawn based on the materials models. The analytical and FE models' results are compared with previously reported test results of the axially loaded SRLAC columns. The proposed analytical and FE models accurately predict the axial behavior and capacities of the new types of SRLAC columns with acceptable agreements for the load-displacement curves. The LWAC strength, steel section ratio, and steel section configuration affect the contact stress between the concrete and steel sections. The average ratios of the ultimate test load to the three analytical models and FEA model loads, Put /Pa1, Put /Pa2, Put /Pa3, and Put /PFE1, for the tested specimens are 0.96, 1.004, 1.016, and 1.019, respectively. Finally, the analytical parametric studies are also studied, in terms of the effects of confinement, LWAC strength, steel section ratio, and the reinforcement ratio on the axial capacity of the SRLAC column. When concrete strength, confinements, area of steel sections, or reinforcement bars ratio increased, the axial capacities increased.

• 한국환경복원기술학회지
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• 제20권3호
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• pp.33-44
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• 2017

This study investigated in the vascular plants of special protection zones (the native land of Berchemia berchemiaefolia in Sadam-ri and Gallon valley) of Songnisan National Park and identified the whole vascular plants. The numbers of vascular plants were summarized as 273 taxa including 82 families, 182 genera, 236 species, 3 subspecies, 28 varieties and 6 forms. Woody plants were identified as 124 taxa (45.4%) and herbaceous plants as 149 taxa (54.6%). A total of 107 taxa were identified in the area of Sadam-ri, and 246 taxa were found in the Gallon valley. A total of 8 taxa of rare plants were identified, each of which was divided into 1 taxa of endangered (EN; Daphne pseudomezereum var. koreana), 3 taxa of vulnerable (VU; Paeonia japonica, Berchemia berchemiaefolia and Iris minutiaurea), 3 taxa of least concern (LC; Aristolochia contorta, Syringa patula var. kamibayshii and Goodyera schlechtendaliana) and 1 taxa of data deficient (DD; Alangium platanifolium). The Korean endemic plants were 9 taxa (Clematis trichotoma, Thalictrum actaefolium var. brevistylum, Aster koraiensis, Cirsium setidens, etc.). In the specific plants by floristic region were 34 taxa, a degree I were 17 taxa (Chloranthus japonicus, Celastrus stephanotifolius, etc.), 9 taxa of a degree II (Euonymus pauciflorus, Acer triflorum, etc.), 4 taxa of a degree III (Aconitum longecassidatum, Angelica gigas, etc.), 2 taxa of a degree IV (Ulmus macrocarpa and Daphne pseudomezereum var. koreana), 2 taxa of a degree V (Berchemia berchemiaefolia and Alangium platanifolium). The naturalized plants were 5 taxa including Fallopia dumetorum, Trifolium repens, Ailanthus altissima, Oenothera biennis, Erigeron annuus. Naturalization rate (NR) was 1.8% of all 273 taxa of vascular plants and the invasive alien plants were not found. The purpose of this study is to identify the flora that grows in the special protection zones of Songnisan National Park and provide the basic data for the management of the special protection zone in the future.

• 설비공학논문집
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• 제27권11호
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• pp.574-580
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• 2015

Climatic zone in building code is an administrative district classification reflecting regional climatic characteristics. Use of Degree-Days is a fundamental method that can be used in various building design codes, analysis of building energy performance, and establishment of minimum thermal transmittance of building envelopes. Many foreign countries, such as the USA, the EU, Australia, Italy, India, China, etc., have already adapted climatic zone classification with degree-days, precipitation or amount of water vapor based on the characteristics of their own country's climate. In Korea, however, the minimum requirements for regional thermal transmittance are classified separately for the Jungbu area, Nambu area and Jeju Island with no definite criterion. In this study, degree-days of 255 Korean cities were used for climatic zone classification. Outdoor dry-bulb temperature data from the Korea Meteorological Administration for 1981~2010 was used to calculate degree-days. ArcGIS and the calculated degree-days were utilized to analyze and visualize climatic zone classification. As a result, depending on the distribution and distinctive differences in degree-days, four climatic zones were derived : 1) Central area, 2) Mountain area of Gyeonggi and Gangwon provinces, 3) Southern area, and 4) Jeju Island. The climatic zones were suggested per administrative district for easy public understanding and utilization.

• 한국환경과학회지
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• 제20권3호
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• pp.341-350
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• 2011

For the reconstruction of the past vegetational changes in Jeju Island, Korea, pollen analysis and radiocarbon dating on the sediments obtained from the Mulyeongari fen were carried out. By the results, the vegetational changes around the Mulyeongari fen from ca. 3,300 cal. yr BP to the present can be interpreted and reconstructed. The pollen record from the Mulyeongari fen was divided into two local pollen assemblage zones and three sub-pollen assemblage zones. Zone I (Quercus-Carpinus-Herbs Zone) was characterized by the predominance of Quercus(30~63%), Carpinus(9~35%) and herbs(40~424%). Zone II was characterized by three sub-pollen assemblage zones and the high occurrence ratio of the tree layer in comparison with Zone I. In Zone IIa (Quercus-Carpinus Zone), herbs(3~161%) were drastically decreased in predominance of Quercus(28~56%) and Carpinus(14~31%). In Zone IIb (Carpinus-Quercus Zone), Carpinus(36~48%) was preferentially increased but Quercus(29~39%) was slightly decreased. In Zone IIc (Quercus-Carpinus Zone), Carpinus(26~38%) was decreased inversely but Quercus(36~50%) was increased. In addition, Cyperaceae was also increased to 52%. Consequently, it is suggested that cool temperate southern/sub-montane vegetation composed of Quercus and Carpinus which was physiognomy of deciduous broad leaved forest was distributed around the Mulyeongari fen from ca. 3,300 cal. yr BP. In addition, Cyclobalanopsis(4~23%), Castanopsis(1~12%) and Myrica(under 1%) which are warm-temperate evergreen deciduous forest components were constantly appeared from this period. Accordingly, it can be inferred that the present vegetation type around the Mulyeongari fen was formed from ca. 180 cal. yr BP.

• 한국지리정보학회지
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• 제11권2호
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• pp.13-27
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• 2008

본 연구에서는 강우 시 발생하는 초기 유출수의 오염부하를 저감할 수 있는 용도지구별 최적지를 분석하여, 용도지구를 재구성하고, 이에 따라 배출되는 오염물의 저감효과를 도시수문모형을 이용하여 모의하였다. 이를 위해 지표에 축적되어 있는 비점오염원의 양을 조사하였으며 대상지역의 강우유출수를 조사하였다. 조사된 결과를 이용하여 초기 유출수 오염저감을 위한 입지조건을 설정하고 각 인자별 적지를 분석하였다. 각 인자별 가중치 설정을 위해 AHP 분석을 실시하였으며 산출된 가중치와 입지조건별 적지 점수를 연산하여 최종 적지를 분석하고 도시수문모형을 통해 저감효과를 모의하였다. 적지분석 결과, 단독주택지와 아파트 지역은 현재 용도지구와 흡사한 지역에 적지가 분석되었다. 학교지역은 현재의 상업지역의 중심지가 적지로 분석되었고 공원지역은 소규모 공원의 적지가 추가되었다. 상업지역은 대상지의 가장 안쪽의 지역이 적지로 분석되었다. 용도지구 변경에 따른 저감효과 모의 결과, 초기유출수의 BOD 농도가 최대 91.2%에서 최저 0.09% 감소하였다. SS의 농도는 최대 72.74%에서 최저 0.31% 감소하였다.

• 터널과지하공간
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• 제18권2호
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• pp.134-148
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• 2008

암반의 초기응력 상태는 방사성 폐기물 지층 처분장의 적합성을 판단하는데 중요한 요소이다. 본 연구에서는 3차원 개별요소법을 이용하여 스웨덴 방사성 폐기물 처분장 후보지 중 하나인 오스카샴 지역에서 대규모 변형대가 초기응력에 미치는 영향을 살펴보았다. 수치해석에서는 부지조사 과정에서 확인된 변형대를 모델에 포함시켰으며 원거리 지각응력을 경계조건으로 사용하였다. 현지 암반에서 관찰되는 초기응력값의 변화 양상이 수치해석에서도 재현이 됨으로써 수치해석이 암반의 초기응력상태를 이해하는데 유용하게 쓰일 수 있음을 확인하였다. 수치해석을 통한 예측값과 초기응력 측정값과의 차이는 측정된 자료의 양호한 정도, 지질모델 및 변형대의 물성치의 불확실성 등에 기인하는 것으로 생각된다.