PURPOSES : In this study, an empirical approach was established to estimate the parameters of the resilient modulus based on various geotechnical properties of subgrade soils. METHODS : Multiple regression analyses were performed to analyze the relationship between resilient modulus (k1) and deformation. The most important factors are the #200 sieve passing ratio, moisture content, and dry unit weight of the soil. The applicability of this approach was verified using selected field data and the literature. RESULTS : The correlation between the results predicted using the prediction equation of the model constant (k1) and the actual k1-value was high. The applicability of the prediction equation was considered high owing to its high suitability with the existing data. The range of values obtained using the constant prediction equation of the proposed model was also judged to be reasonable. In the comparison of the CBR value of the subgrade material of the actual design section and the predicted elastic modulus (k1), almost no relationship was observed between the CBR and the model coefficient (k1). Thus, the estimation of the elastic modulus through CBR is likely to contain errors. CONCLUSIONS : Based on these results, the parameters of the universal model can be predicted using the stress-dependent modulus model proposed in this study.

In the case of the Pohang earthquake, which had a magnitude of 5.4 in 2017, geotechnical damages such as liquefaction and ground settlement occurred. The need for countermeasures has emerged, and experimental research in the Pohang area has continued. This study collected undisturbed samples from damaged fine-grained soil areas where ground settlement occurred in Pohang. Cyclic tri-axial tests for identifying the dynamic characteristics of soils were performed on the undisturbed samples, and the results were analyzed to determine the cause of ground settlement. As a result of the study, it was determined that in the case of fine-grained soils, ground settlement occurred because the seismic load as an external force was relatively more significant than the shear resistance of the very soft fine-grained soils, rather than due to an increase in excess pore water pressure.

Myanmar's soil is diverse in terms of climate and topography, including the central dry zone, hilly and upland areas, deltas, and coastal zones. As a result, crops such as rice, sesame, groundnuts, green gram, and maize are grown as major crops. Some soils are difficult to cultivate due to topographic constraints and permanent forests. Soil fertility was classified according to the physical and chemical characteristics. Based on these data, classification, and a soil survey, a soil map was made by the Land Use Division of Myanmar Agriculture Service. Myanmar's soil was classified into 24 soils according to the WRB classification by FAO/UNESCO, and soil maps were produced at the national level and for each of the 14 states and divisions. This study sought to contribute to efficient land use and sustainable agricultural development in Myanmar by understanding Myanmar's agricultural conditions and soil types.

최근 원예작물의 지속가능한 생산을 위한 작물 생육환경 센 싱 기반 복합환경제어시스템 연구와 산업적 이용이 부각되면 서, 노지재배에 적용하기 적합한 토양센서 활용 방안 연구가 활발히 이루어지고 있다. 본 연구는 산업 및 연구 현장에서 많 이 사용되고 있는 TEROS 12 FDR 센서(frequency domain reflectometry sensor)를 노지 과수원의 토양에 알맞게 활용 하기 위하여 국내 세 지역 과수원 토양의 토성별 FDR 센서 활 용 방법을 제시하고자 수행하였다. 실제 과수가 재배되고 있 는 각 과수원에서 토양을 채취하여, 토성 및 토양수분보유곡 선을 조사하였으며, 토양별 TEROS 12 센서 Raw 값과 이에 대응하는 용적수분함량 값을 선형 회귀 분석, 3차 회귀 분석을 통해 보정식을 얻은 뒤 제조사에서 제공하는 광질 토양 보정 식과 비교 분석하였다. 채취한 세 과수원의 토양은 모두 토성 이 달랐으며, 토성에 따라 각 보수력에 따른 용적수분함량 수 치에 차이가 있었다. 또한, TEROS 12 센서 보정식에서는 모 든 토양에서 3차 회귀 분석 보정식이 결정계수 0.95 이상으로 가장 높게 나타났으며, RMSE도 가장 낮게 나타났다. 제조사 에서 제공하는 보정식을 사용하여 TEROS 12 센서의 용적수 분함량을 보정할 경우 토양에 따라 실제 수치에 비해 최대 0.09－0.17m3·m-3가량 낮게 나타나, FDR 센서 사용시 적용 토양에 알맞은 보정이 반드시 선행되어야 함을 확인하였다. 또한 토성에 따라 토양의 보수력 구간에 따른 용적수분함량 범위의 차이가 있었으며, 토양 용적수분함량의 수치 해석에 보수력 정보가 수반되어야 할 것으로 나타났다. 또한, 사질이 많은 토양에서는 관수 개시점 측정을 위해 FDR 센서를 활용 하는 데 있어 용적수분함량 측정 범위가 상대적으로 좁아 정 밀도가 떨어질 것으로 판단되었다. 결론적으로 토양에서 FDR 센서를 통해 토양수분의 변화를 알맞게 해석하고 노지 에서 알맞은 관수 시점을 선정하기 위해서는, 적용 토양의 수 분보유특성을 파악하고 FDR 센서 보정을 선행하여 올바른 토양 수분 정보 제공이 필요할 것이다.

PURPOSES : The aim of this study is to review freeze-and-thaw testing apparatuses, develop a freeze-and-thaw testing setup with a test protocol, test the freeze-and-thaw properties of soils collected from different parts of South Korea, and suggest an index for frost susceptibility criteria for soils found in South Korea. METHODS : Based on a literature review, a new freeze-thaw testing setup was developed. In addition, a test protocol was developed for freeze-thaw testing. Soils collected from different parts of South Korea and bedding sand used for block pavements were tested to determine whether the measurements from the newly developed test setup could capture important freeze-thaw characteristics of the soils. Finally, to develop local frost susceptibility criteria, a parameter including both the vertical deformation and thermal conductivity characteristics of the soils was suggested. RESULTS : The results from the laboratory experiments indicate that the newly developed freeze-and-thaw setup captures the required parameters to quantify the responses of soils subjected to cyclic freeze-and-thaw testing. In addition, a vertical deformation of up to 2.437 mm is measured. Moreover, seven soils out of the nine tested soils are classified as having a medium frost susceptibility, whereas the remaining two show low frost susceptibility. The bedding sand experiment also shows that there is a possibility of having a frost susceptible condition based on the moisture content. When submerged, the bedding sand is classified as having a medium frost susceptibility. CONCLUSIONS : The "HEART" freeze-thaw testing setup was able to capture the parameters required for evaluating the frost susceptibility of soils. This setup and testing procedure could be further used to test and prepare criteria for classifying the frost susceptibility of soils found in South Korea.

이 연구에서는 D광산 주변 A지역을 대상으로 주요 오염물질인 비소, 납에 대하여 토양 내 존재형태 를 확인하고 광물상을 파악하여 오염 토양의 정화방법을 제시하고자 하였다. D광산 주변 A지역 토양의 비소의 농도는 70.73mg/kg, 납의 농도는 612.80mg/kg로 토양오염공정시험기준의 우려기준을 초과하 였다. 비소는 대부분 잔류 형태로 약 50% 존재하였고, 약 40%가 철-알루미늄 산화물 결정화 형태로 존재하였다. 납은 철-망간 산화물과 결합된 형태로 약 50% 존재하였고, 잔류 형태로는 약 20% 존재하 는 것으로 나타났다. XRD 결과, 비소가 포함되어 있는 라벤듈란(NaCaCu5(AsO4)4Cl·5H2O)과 납과 비 소가 포함되어 있는 기터마나이트(Pb3As2S6) 등이 확인되었다. 연구지역의 비소 및 중금속 오염원은 광 물찌꺼기가 토양에 직접적으로 유입되어 산화광물의 입자상으로 존재하는 비율이 높은 것으로 판단되 며, 특히 미립자에 오염물질이 분포하는 것으로 나타나 이를 선별하여 농축된 오염물질을 1차적으로 제 거하여 정화대상의 양을 저감하는 방안도 필요하다고 판단된다.

PURPOSES: The purpose of this study is to identify the road-subsidence mechanism in unsaturated sandy soils. METHODS: A series of soil chamber tests were conducted under various conditions. RESULTS: The cavity-expansion characteristics in unsaturated sandy soils due to seepage were affected by the outlet size, seepage intensity, relative density, and fine content. CONCLUSIONS: In unsaturated sandy soils, the cavity-expansion speed was affected by the outlet size, relative density, seepage intensity, and clay content; however, the cavity-expansion shape was very similar. As the outlet size and seepage intensity increased, the cavityexpansion speed increased. As the relative density increased, the cavity-expansion speed increased because of a sudden decrease in shear strength, resulting from the increased saturation (reduction of matric suction). The cavity expanded faster with the increasing clay content, up to a certain threshold. It expanded at a slower rate once it passed the threshold. Finally, it reached a stable state where the cavity did not expand due to seepage.

In order to compare greenhouse gases emission from different animal manures and to explore how different animal manures effect on soil mineralization, three kinds of materials, cattle, goat and chicken manure were amended to soil for 14 days incubation as CtS (cattle manure-amended soil), GS (goat manure-amended soil) and ChS (chicken manure-amended soil). Cumulative NH3 emissions in all treatments were rapidly increased until day 7 and then it was slightly increased in three manure-amended soils but maintained in control until day 14. GS had the highest NH3 emission at 0.14 mg kg-1 during the entire experimental period. Emissions of CO2 were highly increased by 7.8-, 9.0- and 12.4-fold in CtS, GS and ChS, respectively, compared to control at day 14. A significant increase of N2O emission in all treatments occurred within 5 days and then it was slightly increased until day 14. N2O emission was 2-fold higher in all manure-amended soils than that of control. Compared to day 1, inorganic N (NH4 + plus NO3 --N) content was highly increased in all four treatments at day 14. The increase rate was the highest in CtS treatment. Net N mineralization was increased by 4.0-, 2.4- and 2.9-fold in CtS, GS and ChS, respectively, compared to control. These results indicate that increase of NH3, CO2 and N2O gas emissions was positively related to high N mineralization.

This experiment was conducted to establish proper irrigation method for water spinach, subtropical vegetable in plastic film house soils to prepare to future global warming of the Korean peninsula. The evaluation of irrigation with 4 different levels as −20, −40, −50 kPa as a starting point(water potential) were compared to –33 kPa as control. All treatments were ended when water potential reached at –10 kPa respectively. The amount of irrigated water, N content, plant growth and fresh yield were investigated. As a result, water potential was correlated positively with irrigation starting point in cultivation period and irrigation times, but the amount water irrigated per time, N content of harvested plant, fresh and dry yield showed negative correlation. The contents of crude protein, P, K, Ca, Fe of harvested part were most high in –50 kPa treatment. We concluded that –50 kPa was optimal irrigation starting point for water spinach cultivation in unheating plastic film house.

대반하[大半夏: Pinellia tripartita(Blume) Schott]는 천남성과에 속하는 다년생 초본식물로써 중국, 일본, 우리나라를 포함한 아시아 전역에 분포하며 꽃과 전초가 아름다워 최근 원예용으로도 많이 이용 되고 있으나 체계적인 대량번식 체계가 구축되어 있지 않다. 본 연구에서는 조직배양을 통해 증식된 대 반하 기내 식물의 토양조성별 괴경 생육을 조사하여 비교하였다. 기내 증식된 대반하 괴경의 크기에 따 라 직경이 1cm 이상인 경우 TypeⅠ, 1cm 이하를 TypeⅡ로 나누어 6종의 조합상토에 파종하여 괴경의 비대와 생육을 조사하였다. 괴경의 비대와 전초의 생육변화를 확인하기 위하여 초장, 잎 수, 마른 잎 수, 괴경 수, 괴경 크기, 생체중 및 건물중을 8주간 변화를 측정한 결과, Type I와 II 모두 코이어 68.0%, 피트모스 14.7%, 펄라이트 3.0%, 버미큘라이트 7.0% 및 제오라이트 7.0%로 구성된 조합상토 B에서 가장 우수한 생육을 보였다. 특히 TypeⅠ은 조합상토 B에서 괴경 크기와 생체중이 각각 45%와 101%를 보였으며, 이는 생육이 가장 좋지 못했던 처리구인 조합상토 E(코이어 14.3%, 피트모스 14.3%, 펄라이트 42.9%, 버미큘라이트 14.3% 및 제오라이트 14.3%)와 약 2배의 차이를 보였다. 이러한 연구 결과는 종자번식이 어려운 대반하의 기내 대량증식을 통한 육묘에 있어 안정적인 토양 순화와 대규모 배양묘 생산을 위한 중요한 기초자료로 활용할 수 있을 것으로 사료된다.

경상남도 김해시 주촌면 내삼리 땅밀림 산사태 피해지를 대상으로 복원 8년 후 훼손복원지와 인접 산 림지의 유기물층 및 토양층의 이화학적 특성을 조사한 결과 유기물층의 건중량 및 탄소함량은 훼손복원 지 7690kg/ha와 34.08%, 인접 산림지 15360kg/ha와 45.21%로 훼손복원지가 유의적으로(P<0.05) 낮 게 나타났다. 또한 훼손복원지내 유기물층의 질소(N), 인(P), 칼륨(K), 칼슘(Ca), 마그네슘(Mg), 구리 (Cu), 망간(Mn), 아연(Zn)함량은 인접 산림지에 비해 유의적으로 높았으나, 알루미늄(Al) 함량은 훼손 복원지와 인접 산림지 간 유의적인 차이가 없었다. 토양층의 경우 토양용적밀도는 훼손복원지 1.31g/cm3, 인접 산림지 0.88g/cm3, 모래함량은 훼손복원지 75%, 인접 산림지 38%, 토양 pH는 훼손 복원지 pH 5.93, 인접 산림지 pH 3.96으로 훼손복원지가 유의적으로 높게 나타났다. 그러나 탄소, 질 소, 칼륨, 마그네슘저장량은 훼손복원지와 인접 산림간 유의적인 차가 없었다. 본 연구결과에 따르면 훼손복원지는 토양 용적밀도나 모래함량이 인접산림지에 비해 증가하여 토양물리적 성질이 악화되는 것 으로 나타났다.