• Geomechanics and Engineering
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• 제22권6호
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• pp.475-488
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• 2020

The recent increase in the use of Expanded Polystyrene (EPS) geofoam in construction and geotechnical projects has driven researchers to investigate its behavior, more deeply. In this paper, a series of experimental tests to investigate the stress-strain behavior and the mechanical properties of EPS blocks, under monotonic axial loading are presented. Four different densities of cylindrically shaped EPS with different dimensions are used to investigate the effects of loading rate, height and diameter, as well as the influence of the density of EPS on the stress-strain response. The results show that increasing the height of the EPS samples leads to instability of the sample and consequent lower resistance to the applied pressure. Large EPS samples show higher Young's modulus and compressive resistance due to some boundary effects. An increase in the rate of loading can increase the elastic moduli and compressive resistance of the EPS geofoam samples, which also varies depending on the density of the samples. It was also determined that the elastic modulus of EPS increases with increasing EPS density. By implementing an efficient numerical procedure, the stress-strain response of EPS geofoam samples can be reproduced with great accuracy. The numerical analysis based on the proposed method can used to evaluate the effect of different factors on the behavior of EPS geofoam.

• 한국유기농업학회지
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• 제20권1호
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• pp.21-36
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• 2012

In this study, the assessment of livestock manure nitrogen loading for recycling farming in Yeoju-Gun carried out comparing manure units based on the cultivation areas and the N-amount of manure that are generated from livestock manure. Manure units (MU) are used in the permitting, registration, because they allow equal standards for all animals based on manure nutrient production. An MU is calculated by multiplying the number of animals by manure unit factor for the specific type of animal. The manure unit factor for MU determination was determined by dividing amounts of manure N produced 80kg N/year. In this study, manure unit by nitrogen concentration and amount of animal manure was calculated as follows: Hanwoo multiplied by 0.36, dairy cows multiplied by 0.8. swine multiplied by 0.105. The laying hens and broilers multiplied by 0.0079, 0.0049, respectively. The analysis of liquid manure unit per ha shows that the N loading by LMU is quite different by region. When it comes to nitrogen loading, the LMU per ha of cultivated land in excess of the N-amount was the highest in the Bukne-myeon province with 2.76 MU/ha, which is higher than the appropriate level. The Ganam-myeon province came next with 2.53 LMU. To be utilized as a valid program to build the environmentally friendly agricultural system, diverse measures shall be mapped out to properly determine manure units, evaluate N-loading and to properly manage their nutrient balance of each region.

• 한국농공학회논문집
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• 제60권2호
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• pp.85-93
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• 2018

This study investigated the structural behavior and field applicability of sandwich type GFRP arches with polymer mortar in core. As a result, in case of crack loading and failure loading, total strains at crown were the highest; the fracture strain at crown was 0.01690, which is 4.2 times greater than the fracture strain (0.004) of cement concrete. The 3 % deflection load was 17.42 kN, the flexural strength was $163.98{\times}10^{-3}GPa$, and the flexural elastic modulus was 11.884 GPa. From load-deflection relationship up to 3.5 % deflection, 3D analysis results and experimental values were observed to be almost identical. It was considered reasonable to set a deflection rate limit to be 3 % for structural safety purpose. The standard external flexural strength of semicircular arch used in this study was approximately 2.64 times higher than that of hume pipe (2 type standard) and tripled composite pipe. The external pressure strength at fracture was approximately 1.57 times higher than that of hume pipe. It was confirmed that the implementing semicircular arch had mechanically more advantage than the circular pipe. Optimum member thickness was 8~53 mm according to arch radius of 450~1,800 mm and cover depth of 2~10 m. It was found that the larger strength could be obtained even if the thickness of member was smaller than that of concrete structure. In field application study, figures and equations were derived for obtaining applicable cover depth and optimum member thickness according to loading conditions. These would be useful data for design and manufacture of sandwich type semicircular arch.

• 한국축산시설환경학회지
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• 제18권3호
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• pp.235-246
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• 2012

현대농업의 여러 가지 폐해를 시정하고 지속가능한 농업시스템으로 전환하기 위해서는 지역단위의 경축순환농업시스템을 갖추는 것이 필요하다. 이것은 친환경농업은 물론이거니와 관행농업에서도 시급히 도입되어야 할 대안이다. 본 연구에서는 분뇨단위 설정기준을 도별 지역에 적용하여 도별 분뇨단위를 산출하여 농경지의 N-부하량과 농지의 가축분뇨 수용량을 평가하여 가축생산과 경작지를 연계한 경축순환농업의 적용 방안을 검토하였다. 1. 농경지의 ha 당 N-부하량 (MU/ha)은 경기도가 2.7 (216 kg/ha), 충청남도가 2.54 (203 kg/ha)로 높은 부하량을 나타내었으나 강원, 전남, 충북 지역은 1.6 이하로 낮게 나타났다. 분뇨단위 결과로 볼 때, 경기도, 충남지역은 가축분뇨의 농경지 부하량이 수용능력에 비하여 높은 지역으로 평가된다. 이에 비하여 전남, 전북, 경남, 충남은 가축분뇨를 시용 할 수 있는 작물재배 면적이 높아 자원화 수용능력이 높은 도로 나타났다. 2. 가축분뇨 부하량과 작물의 양분수용능력을 동시 평가한 순환수지는 전남이 1위, 전북이 2위, 경남이 3위로 남부지방 3개 군이 가축분뇨 부하량에 비하여 자원화 용량이 높아 순환수지가 양호한 것으로 나타났다. 강원, 충북의 순환수지 순위는 각각 4, 5위를 나타내었다. 충남, 경북, 경기도는 가축분뇨 부하량이 높으나 자원화 용량이 낮아 6, 7, 8 위로 평가되었다. 특히 경기도는 가축분뇨 부하량이 높고 자원화 용량은 낮아 양분 순환수지가 가장 불량한 것으로 나타났다. 3. 가축분뇨 발생량으로 추정한 N-부하량과 농경지의 수용량을 예측해 보면 우리나라 도별 농경지는 전체적으로 가축분뇨를 충분히 유입시킬 수 있는 용량인 것으로 평가되는데 가축분뇨가 지역적 시기적으로 편재되어 있어 이용이 곤란한 것이 문제이다. 따라서 경종과 축산의 연계추진이라는 정책에서 가축분뇨 액비의 자원화 환원용량을 증가시키기 위하여 여름작물 액비 살포 증대와 액비 잠재작물의 액비 살포정책 수립 및 인센티브 정책 추진이 필요하다. 결론적으로 환경보호를 고려한 가축분뇨의 자원화를 위하여 가축분뇨의 N-부하량과 농작물의 자원화 수용능력을 산출하여 순환수지 평가가 필요하며, 유기자원이용과 환경오염방지를 양립시키기 위해서는 이 개념에 따라 가축분뇨 자원화 정책을 수립, 실시하는 것이 기본이라고 할 수 있다. 따라서 축산, 경종 연계 추진을 위하여 도, 시군 지자체에서는 액비 잠재작물의 농경지 환원용량을 증대시키기 위하여 체계적이고 정밀한 정책수립과 실행이 필요하다.

• 환경영향평가
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• 제8권1호
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• pp.93-105
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• 1999

Lately water quality of Daechong Reservoir has become more eutrophicated than ever before and there has been much concern over especially the eutrophication of the embayment near Daejon and Chongju Water Intake Tower every summer. The purpose of this study is to predict the impact of change in the pollutant loading, flowrate, nitrogen and phosphorus release from sediment, SOD(sediment oxygen demand) upon the water quality of Daechong Reservoir by WASP5/EUTR05 in order to suggest water quality management alternatives. The data of Sep. 1995 were used for the calibration of the model and those of Sep. 1997 was for verification. The result of the modeling can be summarized as follows. 1. The 50% increase(decrease) of pollutant loading has caused that of T-N concentration by 0.10-0.14 mg/l, T-P concentration by 0.003-0.005 mg/l, and CBOD concentration by 0.16-0.18 mg/l. But the ratio of DO change by the change of pollutant loading was relatively small. 2. The sensitivity test of NH4 flux to T-N and that of P04 flux to T-P shows that T-N and T-P concentration were changed more in the epilimnion segments (SEG4, SEG5, SEG6, SEG7) than the other segments. As SOD increases, DO was predicted to decrease more especially in the hypolimnion (SEG9-SEG14). 3. As flowrate increase, the concentration of T-N, T-P, and CBOD were predicted to decrease, but DO concentration increased especially in the hypolimnion segments(SEG11, SEG12, SEG13, and SEG14). As the flowrate changed from $119m^3/sec$ to $50m^3/sec$, the concentration of T-N and CBOD in the hypolimnion was predicted to decrease.

• 한국환경보건학회지
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• 제35권5호
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• pp.365-375
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• 2009

Agriculture reservoirs need a systematic approach that can control water purity and water improvement. The area under study, Bunam Lake exceeds the agricultural water standard level due to contamination from the upper stream. When the Taean Enterprise City was planned, the water quality improvement plan was applied to minimize the environmental change. However, in order to continuously maintain the water quality in the Bunam Lake, it was essential to apply the Total Pollution Load Management System (TPLMs). In order to achieve the targeted water quality in the Bunam Lake, standard flow rates and targeted water quality levels were applied to obtain the loading capacity which is as follows : BOD 1,891.2 kg/d, T-N 1,945.7 kg/d, T-P 131.7 kg/d. Also, the regional development load was calculated as, BOD 1,083.6 kg/d, T-N 942.2 kg/d, T-P 61.8 kg/d, which is required to be deceased :- by BOD 378.4 kg/d, T-N 198.9 kg/d, T-P 31.6 kg/d in order to safely achieve the targeted water quality in the Bunam Lake.

• 한국축산시설환경학회지
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• 제18권1호
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• pp.45-56
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• 2012

경종과 축산의 분리에 따른 환경오염 심화, 축산분뇨의 해양투기 금지, 축분뇨 처리비용의 절감 및 자원화, 경축순환농업으로의 전환 필요성 등 시급한 과제를 해소하는 근원적임 방안은 바로 지역단위의 경축순환농업시스템을 갖추는 것이다. 지역순환농업을 위해서는 경종과 축산농업의 부산물에 대한 수급량, 그리고 그것의 비료량을 계산할 수 있는 기준이 있어야 한다. 이를 위한 기준이 바로 가죽단위와 분뇨단위이다. 본 연구에서 우리나라 실정에 적용가능 한 분뇨단위를 도출하기 위하여 우리나라 가축분뇨의 양분특성과 배출량의 연구자료를 토대로 분뇨단위 를 설정하였다. 이를 철원군 지역에 적용하여 읍면별 분뇨단위를 산출, 농경지의 N 부하량을 평가하고, 가축생산과 경작지를 연계한 경축순환농업의 적용 방안을 검토하였다. 그 결과를 요약하면 다음과 같다. 1. 질소기준으로 축종별 연간 발생량을 토대로 산출한 분뇨단위는 한우 0.36, 젖소 0.8, 돼지 0.105로 환산되었다. 또한 육계와 산란계의 분뇨단위는 각각 0.0046, 0.0079로 설정하였다. 2. 농경지의 ha 당 분뇨단위(MU/ha)는 갈말읍이 2.4, 서면이 1.92으로 다소 높은 지수를 나타내었으나 동송읍, 철원읍, 근남면은 1.0 이하로 낮게 나타났다. 분뇨단위 결과로 볼 때, 철원군의 갈말읍, 서면, 김화읍은 분뇨단위가 1.8~2.4 범위에 있으므로 가축분뇨의 공급과 농경지 수용능력이 균형지역으로 분류되며 동송읍, 철원읍, 근남면은 1.0 이하로 가축분뇨의 공급이 부족한 지역이므로 분뇨의 수급불균형을 개선하는 양분관리가 필요하다. 3. 갈말읍은 N-부하량이 2.4 MU/ha를 나타내어 EU 기준 N-부하량인 1.7 MU/ha에 비하여 0.7 MU/ha가 초과되어 2,101 MU (16,238kg)의 질소의 과다부하를 나타내었다. 따라서 이에 해당하는 분뇨를 부하량이 적은 지역인 철원읍이나 동송읍으로 분산하여 자원화하여야 할 것으로 보인다. 또한 서면의 경우 N-부하량이 1.92 MU/ha를 나타내어 0.22 MU/ha가 초과되어 203 MU/kg에 해당하는 분뇨를 부하량이 적은 읍면에 분산하여야 할 것으로 보인다. 4. 철원군 지역별 액비의 공간적 공급량과 잠재수요량을 분석한 결과 액비의 공급지역은 김화읍, 갈말읍, 동송읍이지만 액비의 가장 큰 수요지역은 동송읍이었다. 가축분뇨의 발생량과 친환경적인 액비 시용기준의 설정을 고려 할 때 김화읍과 갈말읍은 N-부하량의 농경지 수용능력을 한계지역이므로 액비 과다상태를 파악 분석하여 지역의 양분관리 정책을 시행해야 할 것이다. 5. 철원군 사례연구 결과를 종합해 보면, 시군내의 읍면단위의 지역별로 N-부하량이 상이하므로 읍면별 분뇨단위 적용을 통하여 가축생산과 경작지를 연계한 지역순환농업체계를 구축하여 지역 축산분뇨 양분관리방안을 수립하는 것이 필요하다. 따라서, 철원군내 축분뇨의 자원화를 극대화하려면 지역별 공급, 수급불균형을 해소하기 위해 농가 및 지역별로 허용 분뇨단위(MU)를 제정, 이를 기준으로 전문적인 관리를 해야 한다. 그리하여 경종농업과 축산농업에서 배출되는 각종 부산물의 수급량, 그것의 비료량 퇴비량을 계산하고, 이를 토대로 농가단위 나아가 철원지역의 읍면단위별로 양분수지가 균형을 이루는 자원순환형 농업으로 전환해 가는 것이 필요하다.

• Journal of Welding and Joining
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• 제20권6호
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• pp.99-99
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• 2002

In order to evaluate the proper fracture strength of microstructures in a steel weldment, smaller size loading ball than used for a conventional small punch(CSP) testing is required due to regional limitation on constitutive structures. In this study, the minimized loading ball(φ 1.5mm) and bore diameter of lower die(φ 3mm) were designed for an advanced small punch(ASP) test. The results obtained from the ASP test were compared with those from a CSP testing for a X20CrMoV121 steel weldment. It was found that the ASP test clearly showed the microstructural dependance on fracture strength and ductile-brittle transition behavior of the weldment. In the ASP test, especially, the cracks tend to initiate for various directions within hemispherical indentation region of an objective structure in SP test. This indicates that the evaluation of more proper fracture strength for F.L+CGHAZ, FGHAZ and ICHAZ can be performed by means of the ASP test in a steel weldment.

• 한국물환경학회지
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• 제29권2호
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• pp.184-195
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• 2013

Urbanization from agricultural/forest areas has been causing increased runoff and pollutant loads from it. Thus, numerous models have been developed to estimate NPS loading from urban area and Long-Term Hydrologic Impact Analysis (L-THIA) model has been used to evaluate effects of landuse changes on runoff and pollutant loads. However, the L-THIA model could not consider rainfall intensity in runoff evaluation. Therefore, the L-THIA model, capable of simulating runoff using 10-minute rainfall data, was applied to the study areas for evaluation of estimated runoff and NPS. The estimated Nash-Sutcliffe coefficient (NSE) values were over 0.6 for runoff, BOD, TN, and TP for most sites and watershed. The calibrated model was further extended to other counties for pollutant load potential evaluation. Pollutant load potential maps were developed and target areas were identified. As shown in this study, the L-THIA 2012 can be used for evaluation runoff and pollutant loads with limited data sets and its estimation could be used in identifying pollutant load hot spot areas for implementation of site-specific Best Management Practices.

• Journal of Trauma and Injury
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• 제34권3호
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• pp.162-169
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• 2021

Purpose: For severe lung injuries or acute respiratory distress syndrome that occurs during critical care due to trauma, extracorporeal membrane oxygenation (ECMO) may be used as a salvage treatment. This study aimed to describe the experiences at a single center with the use of ECMO in trauma patients. Methods: We enrolled a total of 25 trauma patients who were treated with ECMO between January 2015 and December 2019 at a regional trauma center. We analyzed and compared patients' characteristics between survivors and non-survivors through a medical chart review. We also compared the characteristics of patients between direct and indirect lung injury groups. Results: The mean age of the 25 patients was 45.9±19.5 years, and 19 patients (76.0%) were male. The mean Injury Severity Score was 26.1±10.1. Ten patients (40.0%) had an Abbreviated Injury Scale (AIS) 3 score of 4, and six patients (24.0%) had an AIS 3 score of 5. There were 19 cases (76.6%) of direct lung injury. The mortality rate was 60.0% (n=15). Sixteen patients (64.0%) received a loading dose of heparin for the initiation of ECMO. There was no significant difference in heparin use between the survivors and non-survivors (70% in survivors vs. 60% in non-survivors, p=0.691). When comparing the direct and indirect lung injury groups, there were no significant differences in variables other than age and ECMO onset time. Conclusions: If more evidence is gathered, risk factors and indications will be identified and we expect that more trauma patients will receive appropriate treatment with ECMO.