• Journal of Biosystems Engineering
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• 제38권1호
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• pp.9-17
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• 2013

Purpose: The goal of this study was to develop a methodology for the demand forecast of tractor, riding type rice transplanter and combine harvester using an ARIMA (autoregressive integrated moving average) model, one of time series analysis methods, and to forecast their demands from 2012 to 2021 in South Korea. Methods: To forecast the demands of three kinds of machines, ARIMA models were constructed by following three stages; identification, estimation and diagnose. Time series used were supply and stock of each machine and the analysis tool was SAS 9.2 for Windows XP. Results: Six final models, supply based ones and stock based ones for each machine, were constructed from 32 tentative models identified by examining the ACF (autocorrelation function) plots and the PACF (partial autocorrelation function) plots. All demand series forecasted by the final models showed increasing trends and fluctuations with two-year period. Conclusions: Some forecast results of this study are not applicable immediately due to periodic fluctuation and large variation. However, it can be advanced by incorporating treatment of outliers or combining with another forecast methods.

• Geomechanics and Engineering
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• 제23권3호
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• pp.227-244
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• 2020

Earthen structures have an excellent bioclimatic performance, but they are vulnerable against earthquakes. In order to investigate the edification process and costs, a full-scale rammed soil house was constructed in 2004. In 2016-2019, it was studied its seismic damage, durability and degradation process. During 2004-2016, the house presented a relatively good seismic performance (M_w=5.6-6.4). The damaged cover contributed in the fast deterioration of walls. In 2018 it was observed a partial collapse of one wall due to recent seismicity (M_w=5.6-6.1). The 15-year-old samples presented a reduced compressive strength (0.040 MPa) and a minimum moisture (1.38%). It is estimated that the existing house has approximately a remaining 20% of compressive strength with a degradation of about 5.4% (0.0109 MPa) per year (considering a time frame of 15 years) if compared to the new soil samples (0.2028 MPa, 3.52% of moisture). This correlation between moisture and compressive strength degradation was compared with the study of new soil samples at the same construction site and compared against the extracted samples from the 15-year-old house. At 7-14-days, the specimens presented a similar compressive strength as the degraded ones, but different moisture. Conversely, the 60-days specimens shown almost five times more strength as the existing samples for a similar moisture. It was observed in new rammed soil that the lower the water content, the higher the compressive/shear strength.

• 한국컴퓨터정보학회논문지
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• 제24권9호
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• pp.103-108
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• 2019

The purpose of this study is to identify the factors that may affect the 5-year survival of colon cancer through network model and to use it as a clinical decision supporting system for colorectal cancer patients. This study was conducted using data from 2,540 patients who underwent colorectal cancer surgery from 1996 to 2018. Eleven factors related to survival of colorectal cancer were selected by consulting medical experts and previous studies. Analysis was proceeded from the data sorted out into 1,839 patients excluding missing values and outliers. Logistic regression analysis showed that age, BMI, and heart disease were statistically significant in order to identify factors affecting 5-year survival of colorectal cancer. Additionally, a correlation analysis was carried out age, BMI, heart disease, diabetes, and other diseases were correlated with 5-year survival of colorectal cancer. Sex was related with BMI, lung disease, and liver disease. Age was associated with heart disease, heart disease, hypertension, diabetes, and other diseases, and BMI with hypertension, diabetes, and other diseases. Heart disease was associated with hypertension, diabetes, hypertension, diabetes, and other diseases. In addition, diabetes and kidney disease were associated. In the correlation analysis, the network model was constructed with the Network Correlation Coefficient less than p <0.001 as the weight. The network model showed that factors directly affecting survival were age, BMI levels, heart disease, and indirectly influencing factors were diabetes, high blood pressure, liver disease and other diseases. If the network model is used as an assistant indicator for the treatment of colorectal cancer, it could contribute to increasing the survival rate of patients.

• 한국환경농학회지
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• 제20권4호
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• pp.277-283
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• 2001

This paper presents treatment efficiency and plant growth of a surface-flow constructed wetland system (30 meter in length and 10 meter in width) over one year after its establishment on a floodplain of a stream. Cattails (Typha angustiflora) grown on pots were transplanted on one half of its area from inlets and reeds (Phragmites australis) on another half from an outlet. Effluent discharged from a secondary-level treatment plant was funneled into the system. The stems of cattails and reeds emerging in April 2001 grew up to 165.9 cm and 95.3 cm, respectively until July 2001. The number of stems of cattails arid reeds in July 2001 increased by 65% and 100%, respectively, compared with that just after their planting. The growth of cattails was better than that of reeds during study period. The removal rates for SS, $BOD_5$, T-N and T-P was 33%, 43%, 31%, and 51%, respectively. The system was inundated seven times by storms over the monitoring period, which disturbed its environment and led to its lower treatment rates. The increase of SS concentration in effluent after inundation of the system was attributed to the falls of soil particles onto its water surface, which had been attached to the emergent plants by floods. Purification rates for T-N were relatively low for the period of late fall through winter until early spring due to lower water temperature which may have retarded microbial nitrification and denitrification mechanisms. Reduction in T-P concentration during fall and winter was relatively higher than that during summer and spring, which may have resulted from no system perturbations by floods and heavy storms during fall and winter.

• 한국환경복원기술학회지
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• 제4권4호
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• pp.56-63
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• 2001

This paper presents treatment efficiency and plant growth of a subsurface-flow constructed wetland system (23 m in length, 6.5 m in width, 0.65 m in depth) over one year after its establishment on floodplain of a stream in June 2000. An upper layer of 10 cm in depth was filled with course sand and the main biological layer of 50 cm depth with crushed stone with 8 - 15 mm in diameter. The system was planted with common reeds (Phragmites australis) grown on pots. Effluent discharged from a secondary-level treatment plant was funneled into it. Reed stems emerging in April 2001 grew up to 145.9cm until July 2001. The number of reed stems in July 2001 increased by about 11 times compared with that just after planting. The system was inundated seven times by storms over the monitoring period. Reeds were slightly bent after flooding, however they returned to almost upright standing in a couple of weeks. Small portion of inside slope of berm was eroded and the system surface had a sedimentation of 2 - 3 mm in depth. The average removal rates for SS, $BOD_5$, T-N and T-P was 73%, 70%, 53%, and 72%, respectively. The purification efficiencies for SS and $BOD_5$ were fairly good. The reduction rates for T-N was relatively low for the period of late fall through winter until early spring due to lower water temperature which retarded microbial nitrification and denitrification mechanisms. Reduction in the concentration of T-P during fall and winter was relatively higher than that during spring. Leach of phosphorous from plant litters lying on system surface and slight resuspension of precipitated phosphorous in substrates resulted in lower reduction for T-P in spring.

• Environmental Engineering Research
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• 제15권4호
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• pp.197-205
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• 2010

Recent years have witnessed increasing interest in wetland constructions in Korea as a flood control measure during the flood season and for consideration of the ecology during the non-flood season. In this study, hydraulic and hydrologic analyses were performed on a wetland construction plan for use as an alternative sustainable flood defense during the flood season, as well as a wetland that can protect the ecosystem during the non-flood season. The study area was the basin of the Topyeong-cheon stream, which is a tributary of the Nakdong River, including the Upo wetland, which is registered in the Ramsar Convention and the largest inland wetland in Korea. Wetlands were to be constructed at upstream and downstream of the Upo wetland by considering and analyzing seven scenarios for their constructions to investigate the effect of flood control during the flood season; it was found the best scenario reduced the flood level by 0.56 m. To evaluate the usefulness of the constructed wetlands during the non flood season, the water balance in the wetlands was analyzed, with the best scenario found to maintain a minimum water level of 1.3 m throughout the year. Therefore, the constructed wetlands could provide an alternative measure for flood prevention as well as an ecosystem for biodiversity.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.231-231
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• 2020

Unlike conventional treatment technologies, the performance of nature-based facilities were susceptible to seasonal changes and climatological variabilities. This study evaluated the effects of seasonal variables on the treatment performance of constructed wetlands (CWs). Two CWs treating runoff and discharge from agricultural and livestock areas were monitored to determine the efficiency of the systems in reducing particulates, organics, and nutrients in the influent. For all four seasons, the mean effluent suspended solids concentration in the agricultural CW (ACW) increased by -2% to -39%. The occurrence of algal blooms in the system during summer and fall seasons resulted to the greatest increase in the amount of suspended materials in the overlying water. unlike ACW, the livestock CW (LCW) performed efficiently throughout the year, with mean suspended solids removal amounting to 61% to 68%. Algal blooms were still present in LCW seasonally; however, the constant inflow in the system limited the proliferation of phytoplankton through continuous flushing. The total nitrogen (TN) and total phosphorus (TP) removal efficiencies in ACW were higher during the summer (21% to 25%) and fall (8% to 21%) seasons since phytoplankton utilize nitrogen and phosphorus during the early stages of phytoplankton blooms. In the case of LCW, the most efficient reduction in TN (24%) and TP (54%) concentrations were also noted in summer, which can be attributed to the favorable environmental conditions for microbial activities. The mean removal of organics in ACW was lowest during summer season (-52% to 35%), wherein the onset of algal decay triggered a relative increase in organic matter and stimulate bacterial growth. The removal of organics in LCW was highest (54 % to 55%) during the fall and winter seasons since low water temperatures may limit the persistence of various algal species. Variations in environmental conditions due to seasonal changes can greatly affect the performance of CW systems. This study effectively established the contributory factors affecting the feasibility of utilizing CW systems for treating agricultural and livestock discharges and runoff.

• 대한환경공학회지
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• 제31권10호
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• pp.893-900
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• 2009

시화호 인공습지의 유기물생산에 대한 갈대부착조류의 기여도를 평가하기 위하여 유입수의 수질특성이 다른 두 습지(반월천습지와 동화천습지)에서 4월부터 10월까지 매월 부착조류의 1차생산력을 측정하였다. 부착조류의 현존량은 반월천습지와 동화천습지에서 각각 37~3,581 mgChl.a/$m^2$surface stem(평균 655 mgChl.a/$m^2$surface stem), 87~2,093 mgChl.a/$m^2$surface stem(평균 527 mgChl.a/$m^2$surface stem)의 범위로 동화천습지에 비해 반월천습지에서 큰 값을 보였다. 반면 부착조류의 광합성효율을 나타내는 동화계수(assimilation number; AN)는 반월천습지에 비해 TN/TP 비가 작은 동화천습지에서 높았다. 두 습지로 유입되는 유입수의 TN/TP비와 AN사이에서의 음의 상관(r=0.46)으로부터 부착조류의 높은 광합성효율은 낮은 TN/TP와 관련이 있는 것으로 사료된다. 부착조류의 단위면적당 일일 1차생산력은 반월천습지에서 307~2,473 mgC/$m^2$/day, 동화천습지에서 756~2,096 mgC/$m^2$/day로 두 습지 모두 여름에 높은 값을 보였다. 두 습지의 평균 1차생산력은 반월천습지가 부착조류의 현존량이 큼에도 불구하고 1,166 mgC/$m^2$/day으로 동화천습지(1,467 mgC/$m^2$/day)에 비해 낮았다. 이는 AN 값에서 알 수 있듯이 반월천습지의 광합성효율이 동화천습지에 비해 낮았기 때문으로 판단된다. 시화호 인공습지에서 갈대부착조류에 의한 연간 총 유기물생산은 300 tonC/year(습지 전체 유기물생산의 33%)로 습지내 유기물생산에 부착조류의 기여가 큰 것으로 나타났다. 습지내 과도한 유기물생산은 습지의 수처리효율을 저하시킬 수 있으므로 수처리용 인공습지의 관리에 있어서 갈대부착조류의 역할이 고려되어야 한다.

• 헤리티지:역사와 과학
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• 제55권1호
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• pp.223-242
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• 2022

본 연구는 세종대에 삼물회를 조선왕릉에 도입하게 되는 과정을 살펴보고, 1446년(세종 28년) 영릉의 구조적 변화가 갖는 의미를 살펴보는 데 중점을 두었다. 조선초 왕릉은 고려의 석실릉을 답습하여 조성하였다. 조선왕릉으로 처음 지어진 신덕왕후의 정릉은 고려의 공민왕과 노국공주의 정릉·현릉을 건립한 경험을 갖고 있는 김사행이 주도적으로 건립하였다. 이후 박자청이 이어받아 조선 초 석실릉을 건립하였으므로, 고려의 석실구조를 기반으로 조선왕릉이 조성되었다고 보는 것이 적절할 것이다. 그러나 성종대의 『국조오례의』에 기록된 석실의 구조를 살펴보면 고려의 것과는 매우 다르다. 뿐만 아니라 『세종실록』에 기록된 태종과 원경왕후의 석실제도와도 다르다. 가장 큰 차이는 석실에 삼물회를 도입하여 구조적인 보강을 시도하였다는 점이다. 이러한 변화는 1446년(세종 28년) 소헌왕후의 국상으로 영릉(英陵)을 건립할 때, 석실 내에 물이 스며들거나 고이지 않는 밀실한 구조를 만들고자 했던 세종의 의지를 반영한 것이다. 1446년 세종과 소헌왕후의 합장릉으로 조성된 영릉(英陵)과 1452년에 조성된 문종의 현릉(顯陵)은 석실구조 바깥에 삼물회격을 추가로 시공한 석실과 회격의 복합구조체이다. 이것은 1468년(예종 즉위년) 세조의 유교에 따라 석실을 폐지하고 회격만으로 현궁을 만드는데 구조적 기반이 되었다. 즉, 영릉과 현릉의 구조에서 내부의 석실구조를 제거하고, 바깥의 회격만을 시공함으로써 회격 현궁이 조성된 것이다. 이로써 조선왕릉은 『국조오례의』에 기록된 석실과 회격의 복합 구조체인 회격석실릉에서, 석실을 제거하고 회격만을 조성하는 회격릉으로 정착하게 된다. 이러한 전개과정을 살펴볼 때, 1446년(세종 28)에 삼물회로 만든 회격구조를 석실에 결합한 회격석실릉은 조선만의 특별한 석실구조이며, 조선왕릉의 지하구조가 회격릉으로 변천하게 되는 기반이 되었음을 논증한다.

• 한국산림과학회지
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• 제101권2호
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• pp.251-258
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• 2012

2009년부터 2011년까지 3년간 국유림내 사방시설 점검대상지에 대하여 현장점검을 실시하고 그 결과를 분석하였다. 대상지는 총 1,628개소로 사방댐 308개소, 사방지 1,320개소(1,269.05 ha)였으며, 현장조사는 연도별로 3~6월 사이에 실시하였다. 점검대상 사방댐은 1991년~2005년에 시공되었으며 96.4%인 297개소가 2000년 이후에 시공된 것으로 나타났고, 사방지는 1986~2005년에 시공되었으며, 68.6%인 903개소가 2000년 이후에 시공된 것으로 나타났다. 사방댐은 콘크리트댐과 콘크리트전석댐이 각각 205개소와 68개소로 많았으며, 총 308개소의 사방댐 중 296개소가 양호한 것으로 나타났다. 사방지에는 돌쌓기와 돌망태를 이용한 사방구조물이 많이 시설되어 있었으며, 총 1,320개소 중 1,245개소(94.3%)가 양호하였다. 전체적으로 국유림내 사방시설은 양호한 상태를 나타내어 그 기능을 충분히 발휘하고 있는 것으로 나타났다. 사방시설 중 불량한 상태인 것으로 나타난 경우 반드시 보완 보수를 통해 사방사업의 목적이 달성될 수 있도록 해야 할 것이다. 또한 기존 사방시설과 향후 사방사업으로 시공되는 사방시설의 체계적인 유지 및 관리를 위해서는 사방시설 관리 시스템의 구축이 시급하다.