박준호 Park Joon-ho , 김기성 Kim Ki-sung , 박윤식 Park Youn-shik , 김종건 Kim Jong-gun , 허성구 Heo Sung-gu , 김남원 Kim Nam-won , 안재훈 Ahn Jae-hun , 임경재 Lim Kyung-jae

DOI: JKWST Vol.50(No.1) 3-12, 2008

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Soil erosion is a natural process and has been occurring in most areas in the watershed. However, accelerated soil erosion rates have been causing numerous environmental impacts in recent years. To reduce soil erosion and sediment inflow into the water bodies, site-specific soil erosion best management practices(BMPs) need to be established and implemented. The most commonly used soil erosion model is the Universal Soil Loss Equa-tion(USLE), which have been used in many countries over 30 years. The Sediment Assessment Tool for Effective Erosion Control(SATEEC) ArcView GIS system has been developed and enhanced to estimate the soil erosion and sediment yield from the watershed using the USLE input data. In the last decade, the Soil and Water Assessment Tool(SWAT) model also has been widely used to estimate soil erosion and sediment yield at a watershed scale. The SATEEC system estimates the LS factor using the equation suggested by Moore and Burch, while the SWAT model estimates the LS factor based on the relationship between sub watershed average slope and slope length. Thus the SATEEC and SWAT estimated soil erosion values were compared in this study. The differences in LS factor estimation methods in the SATEEC and SWAT caused significant difference in estimated soil erosion. In this study, the difference was -51.9%(default threshold)~-54.5%(min. threshold) between SATEEC and non-patched SWAT, and -7.8%(default threshold)~+3.8%(min. threshold) between SATEEC and patched SWAT estimated soil erosion.

이용직 Lee Yong-jig , 김필식 Kim Phil-shik , 김선주 Kim Sun-joo , 지용근 Keun Jee-yong , 주욱종 Joo Uk-jong

DOI: JKWST Vol.50(No.1) 13-21, 2008

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Water losses in irrigation canals are mainly estimated as the sum of conveyance and delivery water loss. The losses occur via the evaporation, infiltration, gate operation and water distribution processing. Recently, the study regarding these water losses are not satisfactory enough, also delivery water loss has not been mainly considered on field design. The objective of this study is to investigate and analyze the volume of water loss in irrigation canals considering condition of actual farm land. A field measurement was performed at four research sites, which are managed by Korea Rural Community & Agriculture Corporation, to evaluate conveyance and delivery water loss for 2 years. The measurement was performed by canal type, size and designed flow using the inflow-outflow method at a major points such as start and end of each canal, derivation point of canal and inlet of paddy fields. Results of this study showed that water loss ratio in lateral canals was bigger than that of main canal unlike current design standard and the loss decrease as flow increase. The total of water loss ratio including conveyance and delivery water loss in several irrigation canals ranged between 33.25 and 45.0%.

서일환 Seo Il-hwan , 이인복 Lee In-bok , 홍세운 Hong Se-woon , 황현섭 Hwang Hyun-seob , Bitog Jessie Pascul , 유재인 Yoo Jae-in , 권경석 Kwon Kyung-suk , 하태환 Ha Tae-hwan , 김현태 Kim Hyeon-tae

DOI: JKWST Vol.50(No.1) 25-37, 2008

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When livestock facilities in Korea have been changed larger and denser, rearing conditions have been getting worse and the productivity of animal production have been decreased. Especially in the cold season, the minimized ventilation has generally been operated to save energy cost in Korea resulting in very poor environmental condition and high mortality. While the stability, suitability, and uniformity of the rearing condition are the most important for high productivity, the ventilation configuration is the most important to improve the rearing condition seasonally. But, it is so difficult to analyze the internal air flow and the environmental factors by conducting only field experiment because the weather condition is very unpredictable and unstable as well as the structural specification can not be easily changed by the researchers considering cost and labor. Accordingly, an aerodynamic computer simulation was adopted to this study to overcome the weakness of conducting field experiment and study the aerodynamic itself. It has been supposed that the airflow is the main mechanism of heat, mass, and momentum transfers. To make the simulation model accurately and actually, simplified pig models were also developed. The accuracy of the CFD simulation model was enhanced by 4.4 % of errors compared with the data collected from field experiments. In this paper, using the verified CFD model, the CFD computed internal rearing condition of the mechanically ventilated pig house were analyzed quantitatively as well as qualitatively. Later, this developed model will be computed time-dependently to effectively analyze the seasonal ventilation efficiency more practically and extensively with tracer gas decay theory.

홍세운 Hong S. W. , 이인복 Lee I. B. , 홍희기 Hong H. K. , 서일환 Seo I. H. , 황현섭 Hwang H. S. , Bitog J. P. , 유재인 Yoo J. I. , 권경석 Kwon K. S. , 하태환 Ha T. H. , 김기성 Kim K. S.

DOI: JKWST Vol.50(No.1) 39-47, 2008

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Most of the broiler houses in Korea have experienced problems on controlling the environmental conditions such as suitability, stability and uniformity of rearing condition inside the broiler house. It is very critical which if not properly controlled, would cause serious stress on the chickens. It is therefore urgent to develop optimum designs of naturally ventilated broiler house which is appropriate to the four seasons of Korea. Field experiment for this matter is very difficult to conduct due to the unpredictable and uncontrollable weather condition. In this study, the heating load of a naturally ventilated broiler house was calculated using TRANSYS 15 BES program while internal climate and thermal condition were computed using Fluent 6.2. The computed resulted of the conventional ventilation system (A) and upgraded ventilation system (B) (Seo et al, 2007) were compared with each other for cold season. The results of the Building Energy Simulation(BES) indicated that the system B, the upgraded ventilation system made 8% lower total heating load and 47% lower at only the broiler zone compared to the conventional broiler house. Considering the entire broiler house, the existence of middle ceiling made the heating energy 11% lower required than without middle ceiling. Accordingly, the system B with middle ceiling was found to save heating energy by 20% in average. This study showed that the BES program can be a very powerful to effectively compute the energy loads of agricultural building while the energy load is very close related to ventilation efficiency.

박찬기 Park Chan-gi , 원종필 Won Jong-pil

DOI: JKWST Vol.50(No.1) 49-57, 2008

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This study evaluated the flexural properties and fire resistance of polyolefm based structural synthetic fiber reinforced concrete. The effects of differing fiber length, dimension and fiber volume fraction were studied. Flexural and fire resistance test were conducted in accordance with the JCI SF-4 and RABT time heating temperature curve, respectively. The Flexural test results indicated that the polyolefln based structural fiber reinforcement showed an ability to increase the flexural toughness and good fire resistance significantly(as compared to steel fiber reinforcement).

손영환 Son Young-hwan , 김성필 Kim Seong-pil , 장병욱 Chang Pyoung-wuck

DOI: JKWST Vol.50(No.1) 61-68, 2008

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It is essential to analyze and classify the physical characteristics of weathered granite for engineering purposes. This paper is to suggest a physical method to determine the degree of weathering of weathered soils. A new classification method for determining the degree of weathering is suggested, based upon the results from laboratory tests including fall cone test. According to the proposed physical method using fall cone apparatus, the measured values of the samples from the same area show distinctive difference of weathering. The water content tends to increase with increasing the degree of weathering at the same penetration in fall cone test. And relationship between CWI and water content are expressed one equation in Hwaseong area and Ilsan area.

리신호 Rhee Shin-ho , 윤성수 Yoon Seong-soo , 엄성준 Eom Seong-jun , 박진선 Park Jin-seon

DOI: JKWST Vol.50(No.1) 71-81, 2008

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This research was focused on the new model and its utility value of environmental friendly backhouse that overcomes the weaknesses of traditional backhouse and modem backhouse. To develop the model, the characteristics, merits and demerits of backhouses and the effectives of additional materials were analyzed and the study result of Rhee etc.(2005) is based. The design drawing of an ecological backhouse was presented considering the sanitation, environment, economy, and utility among the merits of existing backhouses and it's product showed. The new designed model is considered to conveniences in modern toilet and staff is used instead to water as it is suitable for additional material of night-soil. This product was established at farm house and it's utility was proved. And a farmer easily are able to make this backhouse according it's design drawing.

김진호 Kim Jin-ho , 한국헌 Han Kuk-heon

DOI: JKWST Vol.50(No.1) 85-92, 2008

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This study was carried out to estimate heavy metal loads at plain area of the rural watersheds during farming season in 2006. The experimental area was belonging to Geum River watershed. That was located at the center of South Korea. Water samples were corrected at two kinds of aspects. One is regular sampling(every two month) and the other is irregular sampling(every rainfall event). The result showed that heavy metal properties of regular samples were highest at May and June with lively agricultural activities. Heavy metal concentration of irregular samples was lower than that of regular samples. But the heavy metal loads of irregular samples were high. The correlation between each heavy metals of regular samples was following as Mn-Cd > Mn-Fe > Mn-Al > Fe-Al > Al-Cd. The correlation of irregular samples was following as Fe-AI > Zn-Mn > Fe-Cd > Cd-Al. Loading rates of daily discharge the plain area of designed rural watershed during farming season were Al 3.070 kg/day, Cu 0.526 kg/day, Fe 0.745 kg/day, Zn 0.314 kg/day, Cd 0.010 kg/day, Cr 0.055 kg/day, Mn 0.140 kg/day and Pb 0.098 kg/day. Loading rate of discharge with heavy metals during the survey period was Al(577.23 kg) > Fe(140.08 kg) > Cu(98.93 kg) > Zn(58.99 kg) > Mn(26.34 kg) > Pb(18.51 kg) > Cr(10.34 kg) > Cd(1.93 kg).

조영권 Cho Young-kweon , 김관호 Kim Kwan-ho , 김한중 Kim Han-joong , 최수명 Choi Soo-myung

DOI: JKWST Vol.50(No.1) 95-106, 2008

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Eco-friendly material and implementation methods have become important along with the existing standardized maintenance concept for the irrigation and flood control. However, the intrinsic function of the hydraulic structure is water supply and disaster prevention. Therefore, the material and work methods should be considered both eco-friendliness, durability and safety which are prerequisite elements to maintain the engineering function. In this study eco-friendly material and work methods would be classified into the vegetation based system, eco-friendly concrete system and stone-material system according to the characteristics of material. The quality standard for durability followed KS specification and related regulations. The quality standard for safety and eco-friendliness was set after literature review, and the database was developed using the standard. The structure applicable to onsite - the eco-friendly material and work method were classified based on the function and material of the hydraulic structure. Finally, database has been established for convenient management and selection of the proper material and work method. The eco-friendly material and work method could be searched easily for the convenience of the users, and the web-based data system has been developed for continuous registration of the material and work methods to be developed in the future.