• Asian Journal of Turfgrass Science
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• v.11 no.2
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• pp.105-115
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• 1997

Responses of 'Penncross' creeping bentgrass turf to various fairway cultural practices are not well-established or supported by research results. This study was initiated to evaluate the effects of irrigation frequency, clipping return or removal, and nitrogen rate on leaf and soil nitrogen con-tent in the 'Penncross' creeping bentgrass (Agrostis palustris Huds.) turf. A 'Penncross' creeping bentgrass turf was established in 1988 on a Sharpsburg silty-clay loam (Typic Argiudoll). The experiment was conducted from 1989 to 1991 under nontraffic conditions. A split-split-plot experimental design was used. Daily or biweekly irrigation, clipping return or removal, and 5, 15, or 25 g N $m-^2$ $yr-^1$ were the main-, sub-, and sub-sub-plot treatments, respectively. Treatments were replicated 3 times in a randomized complete block design. The turf was mowed 4 times weekly at a l3 mm height of cut. Leaf tissue nitrogen content was analyzed twice in 1989 and three times in both 1990 and 1991. Leaf samples were collected from turfgrass plants in the treatment plots, dried immediately at 70˚C for 48 hours, and evaluated for total-N content, using the Kjeldahl method. Concurrently, six soil cores (18mm diam. by 200 mm depth) were collected, air dried, and analyzed for total-N content. Nitrogen analysis on the soil and leaf samples were made in the Soil and Plant Analyical Laboratory, at the University of Nebraska, Lincoln, USA. Data were analyzed as a split-split-plot with analysis of variance (ANOVA), using the General Linear Model procedures of the Statistical Analysis System. The nitrogen content of the leaf tissue is variable in creeping bentgrass fairway turf with clip-ping recycles, nitrogen application rate and time after establishment. Leaf tissue nitrogen content increased with clipping return and nitrogen rate. Plots treated with clipping return had 8% and 5% more nitrogen content in the leaf tissue in 1989 and 1990, respectively, as compared to plots treated with clipping removal. Plots applied with high-N level (25g N $m-^2$ $yr-^1$)had 10%, 17%, and 13% more nitrogen content in leaf tissue in 1989, 1990, and 1991, respectively, when compared with plots applied with low-N level (5g N $m-^2$ $yr-^1$). Overall observations during the study indicated that leaf tissue nitrogen content increased at any nitrogen rate with time after establishment. At the low-N level treatment (5g N $m-^2$ $yr-^1$ ), plots sampled in 1991 had 15% more leaf nitrogen content, as compared to plots sampled in 1989. Similar responses were also found from the high-N level treatment (25g N $m-^2$ $yr-^1$ ).Plots analyzed in 1991 were 18% higher than that of plots analyzed in 1989. No significant treatment effects were observed for soil nitrogen content over the first 3 years after establishment. Strategic management application is necessary for the golf course turf, depending on whether clippings return or not. Different approaches should be addressed to turf fertilization program from a standpoint of clipping recycles. It is recommended that regular analysis of the soil and leaf tissue of golf course turf must be made and fertilization program should be developed through the interpretation of its analytic data result. In golf courses where clippings are recycled, the fertilization program need to be adjusted, being 20% to 30% less nitrogen input over the clipping-removed areas. Key words: Agrostis palustris Huds., 'Penncross' creeping bentgrass fairway, Irrigation frequency, Clipping return, Nitrogen rate, Leaf nitrogen content, Soil nitrogen content.

• Journal of the Korean association of regional geographers
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• v.3 no.2
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• pp.37-87
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• 1997

As a results of researches on the cultivation processes and settlement developments on the Mangyoung river valley as a whole could be have four 'Space-Time Continuity' through a [Origin-Destination] theory model. On a initial phases of cultivation, the cultivation process has been begun at mountain slopes and tributory plains in upper part of river-basin from Koryo Dynasty to early Chosun Dynasty. At first, indigenous peasants burned forests on the mountain slopes for making 'dryfield' for a cereal crops. Following population increase more stable food supply is necessary facets of life inducing a change production method into a 'wetfield' in tributory plains matching the population increase. First sedentary agriculture maybe initiated at this mountain slopes and tributory plains on upper part of river basin through a burning cultivation methods. Mountain slopes and tributory plains are become a Origin area in cultivation processes. It expanded from up to down through the valleys with 'a bits of land' fashion in a steady pace like a terraced fields expanded with bit by bit of land to downward. They expanded their land to the middle part of river basin in mid period of Chosun Dynasty with dike construction techniques on the river bank. Lower part of river cultivated with embankment building techniques in 1920s and then naturally expanded to the tidal marshes on the estuaries and river inlets of coastal areas. 'Pioneer fringes' are consolidated at there in modern times. Changes in landscapes are appeared it's own characters with each periods of time. Followings are results of study through the Mangyoung river valley as a whole. (1) Mountain slopes and tributory plains on the upper part of river are cultivated 'dryfields' by indigenous peasants with Burning cultivation methods at first and developed sedentary settlements at the edges of mountain slopes and on the river terrace near the fields. They formed a kind of 'periphery-located cluster type' of settlement. This type of settlement are become a prominant type in upper part of river basin. 'Dryfields' has been changed into a 'wetfields' at the narrow tributory plains by increasing population pressure in later time. These wetfields are supplied water by Weir and Ponds Irrigation System(제언수리방법). Streams on the tributory plains has been attracted wetfields besides of it and formed a [water+land] complex on it. 'Wetfields' are expanded from up to downward with a terraced land pattern(adder like pattern, 붕전) according to the gradient of valley. These periphery located settlements are formed a intimate ecological linkage with several sets of surroundings. Inner villages are expanded to Outer villages according to the expansion of arable lands into downward. (2) Mountain slopes and tributory plains expanded its territory to the alluvial deposited plains on the middle part of river valley with a urgent need of new land by population increase. This part of alluvial plains are cultivated mainly in mid period of Chosun Dynasty. Irrigation methods are changed into a Dike Construction Irrigation method(천방수리방법) for the control of floods. It has a trend to change the subjectives of cultivation from community-oriented one who constructed Bochang along tributories making rice paddies to local government authorities who could be gather large sums of capitals, techniques and labours for the big dike construction affairs. Settlements are advanced in the midst of plains avoiding friction of distances and formed a 'Centrallocated cluster type' of settlements. There occured a hierarchical structures of settlements in ranks and sizes according merits of water supply and transportation convenience at the broad plains. Big towns are developed at there. It strengthened a more prominant [water+land] complex along the canals. Ecological linkages between settlements and surroundings are shaded out into a tiny one in this area. (3) It is very necessary to get a modern technology of flood control at the rivers that have a large volume of water and broad width. The alluvial plains are remained in a wilderness phase until a technical level reached a large artificial levee construction ability that could protect the arable land from flood. Until that time on most of alluvial land at the lower part of river are remained a wilderness of overgrown with reeds in lacks of techniques to build a large-scale artificial levee along the riverbank. Cultivation processes are progressed in a large scale one by Japanese agricultural companies with [River Rennovation Project] of central government in 1920s. Large scale artificial levees are constructed along the riverbank. Subjectives of cultivation are changed from Korean peasants to Japanese agricultural companies and Korean peasants fell down as a tenant in a colonial situation of that time in Korea. They could not have any voices in planning of spatial structure and decreased their role in planning. Newly cultivated lands are reflected company's intensions, objectives and perspectives for achieving their goals for the sake of colonial power. Newly cultivated lands are planned into a regular Rectangular Block settings of rice paddies and implanted a large scale Bureaucratic-oriented Irrigation System on the cultivated plains. Every settlements are located in the midst of rice paddies with a Central located Cluster type of settlements. [water+land] complex along the canal system are more strengthened. Cultivated space has a characters of [I-IT] landscapes. (4) Artificial levees are connected into a coastal emnankment for a reclamation of broad tidal marshes on the estuaries and inlets of rivers in the colonial times. Subjectives of reclamation are enlarged into a big agricultural companies that could be acted a role as a big cultivator. After that time on most of reclamation project of tidal marshes are controlled by these agricultural companies formed by mostly Japanese capitalists. Reclaimed lands on the estuaries and river inlets are under hands of agricultural companies and all the spatial structures are formed by their intensions, objectives and perspectives. They constructed a Unit Farming Area for the sake of companies. Spatial structures are planned in a regular one with broad arable land for the rice production of rectangular blocks, regular canal systems and tank reservoir for the irrigation water supply into reclaimed lands. There developed a 'Central-located linear type' of settlements in midst of reclaimed land. These settlements are settled in a detail program upon this newly reclaimed land at once with a master plan and they have planned patterns in their distribution, building materials, location, and form. Ecological linkage between Newly settled settlemrnts and its surroundings are lost its colours and became a more artificial one by human-centred environment. [I-IT] landscapes are become more prominant. This region is a destination area of [Origin-Destination] theory model and formed a 'Pioneer Fringe'. It is a kind of pioneer front that could advance or retreat discontinously by physical conditions and socio-cultural conditions of that region.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.171-181
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• 1999

A field experiments was carried out to investigate the physicochemical properties of soil and cucumber growth in vinyl house when irrigation point was made at 0.2, 1/3, 0.5 and 1.0 bar. The obtained results was summarized as follow: The taxonomic class of the soil used was loam and each content of the required water was 4.4, 7.3, 9.6 and 13.4 mm per each irrigation time at 0.2, 1/3, 0.5 and 1.0 bar treatments in spring culture, respectively. At 0.2 bar and 1.0 bar treatments, interval of irrigation was 2.3 and 14.8 day, the times of irrigation was 37 and 6, and total irrigation volume was 163.5 and 80.3 mm, respectively. After cucumber culture, pH, EC concentration and exchangeable K content of soil at 0.2 bar treatment was distributed near to the level of improvement target while EC, available $P_2O_5$ and exchangeable base content in other treatments were higher compared to improvement target. At 1.0 bar treatment, ratios of the solid and liquid phase were 44.9 and 27.1%, respectively, and bulk density was $1.26g\;cm^{-3}$ which was the highest among the treatments. At 0.2 bar treatment, the ratio of the solid and liquid phase was 41.7 and 22.8%, respectively, and bulk density was $1.09g\;cm^{-3}$ which was the lowest. The root length and radius at 0.2 bar treatment were best, while those at 1/3 bar were worst. At 0.2 bar treatment, the total yield was 7,269 kg and the weight of good products was 5,677 kg which was the highest among treatments. At 0.33 bar treatment, the yield was the lowest with the high ratio of deformity.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.4
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• pp.292-301
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• 2001

The objectives of this study were to measure the changes in soil moisture regimes and the distribution patterns of inorganic N derived from the fertigated $^{15}N$-labeled urea, and compare them with the results obtained from broadcast-applied soil under the same drip irrigation domain. In fertigated soil, a $^{15}N$-labeled urea solution of $117mg\;N\;L^{-1}$ was applied by surface drip irrigation for 4 weeks. In broadcast-applied soil, no the other hand, 4 g of $^{15}N$-labeled urea(1.87 g N) mixed thoroughly with 5 kg of soil was placed on the surface of packed soil. Soil water status was controlled by drip irrigation scheduled at soil matric potential of -50 kPa. A calibrated time-domain reflectometry probe was installed in the soil vertically 15 cm apart from a drip emitter to control drip irrigation. About 60% of urea-derived inorganic nitrogen was remained in the top zone between 0 and 10 cm depth of fertigated soil, while, most of the inorganic nitrogen (91%) was accumulated in the top zone of broadcast-applied soil. Of inorganic nitrogen derived from urea, the percentage of $NO_3{^-}$ was much higher for fertigation (99%) than for surface application (62%). The relatively lower recovery of urea-derived inorganic nitrogen of broadcast-applied urea-N (51%) than that of fertigated urea-N (89%) was attributable to enhanced $NH_3$ volatilization.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.830-833
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• 2004

Hydraulic structures have been constructed with low cost concrete so as to increase the investment efficiency. But, it has caused to produce structures having excess internal voids inside concrete. As the construction of agricultural irrigation and drainage project is concentrated on off-farming season and scattered in wider area, variation of quality of structures is big and it caused increase of internal voids. Due to that reason, hazardous substance is passing rather freely through the voids causing occur of crack and accordingly life time of structures is getting shortened. It is necessary to make a thesis of design criteria for design strength to increase life time, range of variation of quality, strength of ready-mixed concrete proper to design strength, and water-cement ratio and air content.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.119-122
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• 2001

Annual demand of a precast concrete bench flume used in the irrigation canal of arable land readjustment has continuously increased units recently. The average life time of the precast concrete bench flume was estimated $8{\sim}10$ years, which is too shorter than the life time of in-site placed concrete structures. In order to increase the compressive strength of the precast concrete bench flumes, the highest temperature of being lower than $95^{\circ}C$ was suggested in this study, Through analyzing the relation between the compressive strength and the amount of chloride penetration into concrete specimens, a new formula early estimating durability of the concrete structure was suggested.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1147-1150
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• 2008

The goal of this research is to apply the neural networks models for the disaggregation of the pan evaporation (PE) data, Republic of Korea. The neural networks models consist of the support vector machines neural networks model (SVM-NNM) and multilayer perceptron neural networks model (MLP-NNM), respectively. The SVM-NNM in time series modeling is relatively new and it is more problematic in comparison with classifications. In this study, The disaggregation means that the yearly PE data divides into the monthly PE data. And, for the performances of the neural networks models, they are composed of training, cross validation, and testing data, respectively. From this research, we evaluate the impact of the SVM-NNM and the MLP-NNM for the disaggregation of the nonlinear time series data. We should, furthermore, construct the credible data of the monthly PE data from the disaggregation of the yearly PE data, and can suggest the methodology for the irrigation and drainage networks system.

• Journal of Biomedical Engineering Research
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• v.9 no.1
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• pp.25-30
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• 1988

In this paper, we proposed the bidirectional mono-thermic test for the functional exploration of the vestibules by considering a temeprature variation in the semicirular canals constant for a short time and an inclination of the semicircular canal plan relative to the vertical. Through the proposed test we showed the evidence of an eventual asymmetry between the responses of right and left vestibules. In view of clinical practice, the proposed test has the advantages of saving the test time, of using only one temperature for the ear irrigation and of making only head movements to the given angle for the stimulation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.5
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• pp.83-92
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• 2001

As a result of the recent water resources crisis, development of water management automation system becomes important. This system should be developed with open architecture in order to flexibly meet the spacial and time change of irrigation water demand. Thereby, water management automation system requires open architecture and suitable software program. This study presents an application of object-oriented methodology for Open Water Management Program(OWMP). Accordingly, OWMP provides a high degree of reliability which allows modification of parameters by change of region or time to be possible. OWMP consists of Data Base Management System(DBMS) and Model System. DBMS makes it possible to analyze data related with planning water schedule and establishing database. Model System calculates reservoir inflow, reservoir effluent and basin water demand. An operator decides the reservoir operation with results of Model System and DBMS. OWMP could be adapted to the planning and decision for saving water.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1596-1599
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• 2010

Group method of data handling neural networks model (GMDH-NNM) is used to estimate daily pan evaporation (PE) using limited climatic variables such as max temperature ($T_{max}$), min temperature ($T_{min}$), mean wind speed ($W_{mean}$), mean relative humidity ($RH_{mean}$) and sunshine duration (SD). And, for the performances of GMDH-NNM, it is composed of training and test performances, respectively. The training and test performances are carried out using daily time series data, respectively. From this research, we evaluate the impact of GMDH-NNM for the modeling of the nonlinear time series data. We should, thus, construct the credible data of the daily PE data using GMDH-NNM, and can suggest the methodology for the irrigation and drainage networks system. Furthermore, this research represents that the strong nonlinear relationship such as pan evaporation modeling can be generalized using GMDH-NNM.