Many changes in the scale and structure of the Korean rice cropping system have been made over the past few decades. Still, insufficient research has been conducted on the sustainability of this system. This study analyzed changes in the Korean rice cropping system’s sustainability from a system ecology perspective using an emergy approach. For this purpose, an emergy table was created for the Korean rice cropping system in 2011, 2016, and 202, and an emergy-based indicator analysis was performed. The emergy analysis showed that the total emergy input to the rice cropping system decreased from 10,744E+18 sej year-1 to 8,342E+18 sej year-1 due to decreases in paddy field areas from 2011 to 2021, and the proportion of renewable resources decreased by 1.4%. The emergy input per area (ha) was found to have decreased from 13.13E+15 sej ha-1 year-1 in 2011 to 11.89E+15 sej ha-1 year-1 in 2021, and the leading cause was a decrease in nitrogen fertilizer usage and working hours. The amount of emergy used to grow 1 g of rice stayed the same between 2016 and 2021 (specific emergy: 13.3E+09 sej g-1), but the sustainability of the rice cropping system (emergy sustainability index, ESI) continued to decrease (2011: 0.107, 2016: 0.088, and 2021: 0.086). This study provides quantitative information on the emergy input structure and characteristics of Korean rice cropping systems. The results of this study can be used as a valuable reference in establishing measures to improve the ecological sustainability of the Korean rice cropping system.

PURPOSES : The objectives of this study are to evaluate the condition of concrete bridge decks using the multi-channel ground penetrating radar (GPR) testing and compare the value of its dielectric constant value with actual concrete condition. METHODS : The reflection coefficient method was used to measure the dielectric properties of concrete bridge decks. Air-coupled step-frequency GPR testing was used to measure the time taken for reflection from the interfaces between the layers. Specimens of the asphalt mixture and concrete bridge-deck were collected by field coring. GPR testing was conducted on two bridges with different concrete bridge deck conditions on national highways. After the GPR tests, the actual conditions of the concrete bridge deck were investigated using specimen coring. RESULTS : GPR testing indicated that the dielectric constants of concrete bridge decks in good condition ranged from 8 to 10, whereas those corresponding to poor condition ranged from 4 to 6. The results of GPR testing can determine the actual condition and degree of distress of concrete bridge decks determined from the specimen coring data. Therefore, GPR testing is appropriate for nondestructively evaluating the condition of a concrete bridge deck. CONCLUSIONS : The analysis results of the dielectric constants of the concrete bridge deck obtained from multichannel GPR testing were consistent with the actual bridge deck conditions. In the near future, an additional verification process for this approach under different bridge conditions will be required to improve its precision and ensure reliability.

The process of biological invasion is led by the dynamics of a population as a demographic and evolutionary unit. Spatial structure can affect the population dynamics, and it is worth being considered in research on biological invasion which is always accompanied by dispersal. Metapopulation theory is a representative approach to spatially structured populations, which is chiefly applied in the field of ecology and evolutionary biology despite the controversy about its definition. In this study, metapopulation was considered as a spatially structured population that includes at least one subpopulation with significant extinction probability. The early phase of the invasion is suitable to be analyzed in aspects of the metapopulation concept because the introduced population usually has a high extinction probability, and their ecological·genetic traits determining the invasiveness can be affected by the metapopulation structure. Although it is important in the explanation of the prediction of the invasion probability, the metapopulation concept is rarely used in ecological research about biological invasion in Korea. It is expected that applying the metapopulation theory can supply a more detailed investigation of the invasion process at the population level, which is relatively inadequate in Korea. In this study, a framework dividing the invasive metapopulation into long- and middle-distance scales by the relative distance of movement to the natural dispersal range of species is proposed to easily analyze the effect of a metapopulation in real cases. Increased understanding of the mechanisms underlying invasions and improved prediction of future invasion risk are expected with the metapopulation concept and this framework.

The concrete vacuum tube structure, which must maintain air-tightness, is manufactured in the form of a segment, and it is necessary to install the joints at uniform gap in order to assemble in the field. In this study, member tests were carried out to investigate the air-tightness performance at the joints of the concrete vacuum tube structures.

최근 환경기준이 강화되면서 하수 처리공정에서 생물학적 처리와 탈인시설을 조합한 하이브리드형 고도처리 공정이 빠르게 도입되고 있다. 현재 도입되고 있는 탈인시설은 대부분 응집제 투여를 바탕으로 하는 화학적 처리공정으로 비교적 처리공정과 유지관리가 간단하여 처리효율의 신뢰도가 높은 장점이 있는 반면에 화학약품 비용과 발생된 슬러지의 처분비용 등이 매우 높다는 단점이 있다. 이에 반해 하이브리드형 고도처리시스템을 구축하는데 있어 가장 단순하고 안정적인 단위공정의 하나로 알려진 흡착법은 이온성 물질의 동시제거가 가능하면서도 기후 및 농도에 관계없이 처리효율이 비교적 일정하고, 부생독성물질을 생성시킬 위험성이 없다는 장점을 가지고 있다. 그럼에도 불구하고 흡착법이 하수처리의 탈인공정으로 널리 활용되지 못하는 이유는 인산이온만을 선택적으로 흡착할 수 있는 흡착제가 없기 때문이다. 최근 저자들은 하수처리수를 이용한 컬럼실험을 통해 강염기성은 물론 약염기성 음이온교환수지 모두 하수 중에 다량 함유되어 있는 황산이온의 방해로 인산이온을 거의 흡착하지 못함을 확인하였다. 즉, 고정층 컬럼 실험을 통해 얻은 인산이온의 흡착량은 인산이온만 있을 경우 134 mg/g인데 반해 실폐수의 경우 Cl과 SO4이온의 흡착경쟁 때문에 10.4 mg/g으로 감소하여 실폐수 적용이 불가능하였다.

The PP-g-Vim-CH3I adsorbent, which possesses antibacterial and ion-exchange functions, was synthesized by photoinduced grafting of 1-vinyl imidazole (Vim) onto polypropylene, non-woven fabric and subsequent quaternization using methyl iodide (CH3I). The adsorption properties of PP-g-Vim-CH3I for nitrate ion were studied in batch mode and fixed-bed columns. The adsorption equilibria of NO3-N on PP-g-Vim-CH3I were well described by the Langmuir isotherm model, and the adsorption energy was 9.03 kJ/mol, which indicates an ion-exchange process. Adsorption-kinetic data were fitted with a pseudo-second-order kinetic model. The Bohart-Adams model was found to be suitable for simulating the breakthrough curves obtained from the fixed-bed columns. The fixed-bed sorption capacity of nitrate ion from the model was in the range 100.8 ~ 108.6 mg/g without the presence of competing anions but decreased to the range 55.7 ~ 96.2 mg/ g in groundwater due to adsorption competition with the coexisting anions, especially SO4 2− ion. The PP-g-Vim-CH3I adsorbent could be regenerated by washing with 1.0 N NaCl without serious lowering the adsorption capacity.

In order to establish preventive maintenance and to make a reasonable estimate of the required repair cost for bridges, the related history information of the existing bridge inspection and diagnosis was analyzed. It was analyzed that about 75% of the repair costs were required for the pavement, expansion joining, curb, and railings in the service area of bridges.

The precast modular bridge that combines pre-designed standard modules was constructed by KICT. A field test was performed to estimate the structural performance of this bridge. As a result, this bridge has sufficient safety and serviceability as a highway bridge.

Connecting members are proposed to skip installing formworks in the process of assembling the slab type precast modular bridge. In this study confirms the field applicability of connecting members for rapid construction of slab type precast modular bridge.

이온교환법 또는 흡착법은 기존의 생물학적 처리공정과 연계한 고도처리시스템을 구축하는데 있어 가장 단순하고 안정적인 단위공정의 하나가 되고 있다. 이에 따라 다기능성, 고효율성, 이온 선택성 및 경제성을 갖춘 흡착소재를 개발하기 위해 많은 노력이 이루어지고 있다. 리그노셀룰로오스계 천연 고분자 물질은 자연에 풍부하면서도 저가라는 점에서 다양한 기능성의 흡착소재로 활용되고 있다. 이 중 정미산업의 주요 부산물인 왕겨는 기계적 강도가 높고 일정한 형상과 넓은 비표면적을 가지고 있다는 장점이 있어 생체흡착제 제조 원료로 적합한 특성을 가지고 있다. 우리나라에서는 매년 60만톤 이상의 왕겨가 발생하고 있으며, 이들의 95% 이상이 축산분뇨와 혼합하여 퇴비로 사용되고 있는 실정이다. 본 연구에서는 왕겨의 새로운 재활용 방안으로 생체흡착제 제조를 위한 기질물질로 왕겨의 활용 가능성과 효율성을 검토하기 위해 potassium peroxydisulphate(K2S2O8)를 산화-환원 개시제로 하는 그라프트 중합반응을 통해 왕겨표면에 glycidyl methacrylate(GMA)를 화학적으로 결합시켜 에폭시기(-COC-)를 도입하고, Diethylenetriamine(DETA)과 반응을 통해 에폭시기에 아민기(-NH)를 도입하는 방법으로 음이온 흡착기능성 왕겨흡착제(RH-g-GMA-DETA)를 제조한 다음, 회분식 흡착실험을 통해 아민형 왕겨흡착제의 NO3-N와 PO4-P에 대한 흡착효율 및 흡착특성을 평가하였다. 아민형 왕겨흡착제 RH-g-GMA-DETA의 NO3-N와 PO4-P에 대한 흡착은 Fruendlich 흡착등온식보다는 Langmuir 흡착등온식과 잘 일치하였으며, Langmuir흡착등온식으로부터 구한 최대 단일층 흡착량은 NO3- 68.5 mg/g, PO43- 129.8 mg/g이었다. 흡착은 NO3- 와 PO43- 모두 20분 이내에 평형에 도달할 정도로 빠르게 진행되었으며, 2차 흡착속도식과 잘 부합하는 특성을 보여 chemisorption이 속도결정단계에서 중요한 역할을 함을 알 수 있었다. D-R모델로부터 추산한 흡착에너지는 NO3- 가 9.3 kJ/mol, PO43- 가 140 kJ/mol로 각각 이온교환과 화학적 흡착이 주된 흡착메카니즘으로 작용하였음을 나타내었다. 공존 음이온간 흡착선택성과 흡착에 미치는 pH 영향을 동시에 살펴 본 결과 RH-g-GMA-DETA의 흡착선택성은 SO4>PO4>NO3≥NO2>F의 순이었으며, SO4는 pH의 영향을 거의 받는 흡착특성을 보이는 반면, PO4는 pH가 증가할수록 흡착량이 증가하는 특성을, NO3, NO2 및 F는 pH 5 이상에서는 흡착량이 급격히 감소하는 특성을 보였다.

Inspection Stairs for bridge is basic facility for inspecting abutment. Based on the surveying for inspection stairs for bridge, basic guidelines for inspection stairs for bridge were proposed.

Many accidents by side-wind have been reported worldwide when vehicle passes through the bridges. In order to solve this problem, it needs to investigate the accident cases and to classify the accident types. Therefore, it can lead to adequate plans for prevention.

Recently, The aims to rapid construction and easy maintenance of the road system. As a part of the precast road construction system, this study investigated the deformations and stresses at the end of the precast slab and checked horizontal filler and vertical anchor bolt. Analysis cases selected by each boundary condition and choose proper boundary condition. as choose analytical model result, developed precise analytical models and checked performance of end tip connection.

The objective of this study is to investigate the safety of the slab type precast module. To achieve this, the designed slab type precast module was made using the manufacturing facility for the precast modular superstructure and the flexural performance test was conducted.

The modular road system was proposed to achieve the fast construction and the closed-loop chain of the resources in the field of road construction. In this study, the concept of the joint system that complies with the goal of the development of modular road system was proposed.

In this study, the mock-up test of a girder-type precast module was conducted for evaluated construction applicability. Results of mock-up test, girder type precast module`s process of manufacturing and transport, fabrication, installation was satisfied the construction application.

In this study two kinds of cases were selected in order to develop roadway system. Specifically two boundary conditions were considered with varying support offset. In each case, relatively loading Dead load, Live load, Temperature load, displacement and reaction force were analyzed at the end of slab. As a result, this study performed optimization review of roadway connection.