• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.22-33
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• 1978

To maintain the self-sufficiency of food production , it is required to improved the productivity and increase the effective utilization of land in the double cropping areas using improved cultivation technology. The following reasons encourage this cours of action because the overlapping rice harvest and barely seeding seasons complete for labour, the lower price of barley makes it financially less attractive to grow and these two facts together are responsible for a decrease in barley being planted in certain more seasonably marginal double cropping areas. Fro these reasons, it is desirable to carry out tests to improve the current cultivation techniques . In this interest , the following studies were carried out in the experimental field located at Banweol-myeon, Whasung-jkun, Gyeonggi-do from October 1977 to July 1978 in order to establish the mechanical method of barley cultivation using the power tiller. The summarized results are as follows. 1. The work performance in the seeding operation using the rotary barley seeder was 68 minutes per 10 ares which compares favourably with 408 min/10a using the conventional method. This is only one sixth of the time required by th conventional method. The operating costs using the rotary barley seeder was 1, 463 won per 10 areas as against 3, 486 Won per 10 ares for the conventional method, showing a saving of about 50% in comparison with the conventional method. 2. In the manure spreading operation, the work performance was 25 min/10a for the manure spreading machine , compared to 1089 min/10a for the manual operations. This is about one fourth of the time required by the conventional method, The operating costs were 810 Won/10a for the machine and 857 Won/10a for the manual labour. This cost shows little advantage by the machine over the manual labor costs. The conventional method of manure spreading will continue pending decision which will develope and improve the machine.3. Work performance in the rolling operation using the barley rolIer was 30 min/lOa which compares favourably with 135 min/10a using conventional method. This was one fourth of the time required by the conventional method. The operating costs were 514 Won/103. for the machine and 1, 003 Won/lOa for manual labour. In the weed control operation, the work performance and operating costs were 45min/lOa, 1, 399won/10a for the herbcide application using the power sprayer, 1, 149min/10a 8, 541won/lOa for the conventional method respectively. This is 26 times higher efficiency in comparison to the conventional method. 4. In the harvesting operation using the reaper binder and tiller attachment, the work performance was 60min/lOa and represents a cost of 2, 039won/10a. The con\ulcornerventional method took 640min/10a at a cost of 4, 757won/lOa. The reaper binder showns a saving of one tenth over the conventional method. The automatic thresher is already recommended for the current situations, and is now being used. 5. From a comparison of the results of the above trials, the serial cultivation system using the attachment for the power tiller such as the rotary barley seeder is now to be recommended for the current barley cultivation system. It is also recommend from these results that the mechanized technology now available must be used to improve and maintain the increase in barley production. It is seen th1t this is the only course now avaihble to solve the peak seasonal requirements of labour needed for l11rvesting and seeding between rice and barley cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.8 no.2
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• pp.45-51
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• 1975

The morphological, physical, chemical, and mineralogical characteristics of planosols in Korea were studied in an effort to establish the suitabilition of the planosols for agricultural development. The Yeongog series which are planosols were established in Korea. Results from the Yeongog series are briefly as follows : 1. Morphologically, the surface soils are brown to dark brown friable loam and subsoils are of varied colors but mainly are dark brown, black and pale brown mottles. The texture of these horizons are silty clay loam with moderate to strong platy structure and clay cutans are on the ped faces. The consistences of these horizons are extremely compact and hard when moist and sticky, plastic when wet. The substrata show varied soil colors and loam to clay loam. 2. Physically, the clay content of the Yeongog soils is highest in the subsoils and gradually decreases below the subsoils. Water holding capacity and bulk desity is higher than in other mineral soils. 3. Chemically, the organic matter content is low and soil reaction ranges from very strongly to strongly acid. The cation exchange capacity is medium and base saturation a high. Active iron, easily reducible manganese and available silicate are high compared with normal soils. 4. In chemical composition of clay fraction of the Yeongog series, sesquioxide ratio, $Fe_2O_3$, $K_2O$ and MgO are high. The cation exchange capacity of the clay fraction is also very high. 5. The clay minerals in Yeongog series are mainly kaoline, vermiculite with Al interlayers and illite. The quarts, primary minerals are in the Yeongog soils. 6. These soils are formed in a warm, humid climate under native grasses on the terraces and rolling or hilly footslopes. In soil classification, the Yeongog soils are classified planosols with claypan. According to 7th approximation system in U.S.A., the Yeongog series are classified as Fragiudalfs because they have an argillic horizon, a hard pan and a high base saturation which is more than 35 percent and classified as Eutric Planosols by FAO/UNESCO classification system.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.49-62
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• 2006

The republic of korea has put a great emphasis on the role of the road as widening a social infra-structural facility. Thus, vast amount of money has been invested on the road establishment. As a result, there has been fruitful outcomes in establishing the road system of the nation especially for the flat road with ease. However, in order to have more systematic and sustainable road system, we should turn our attention to more painful and high-cost regions such as mountainous districts and those are to be developed effectively. The configuration of the road is an important factor to be considered in making a decision for the road planning. Nevertheless, current road planning criterion has no such clarified and objective judging standard for figuring the configuration of the road out and, as a result, speed planning can be decided incorrectly. our research has acknowledged the necessity of estimating the configuration of the road and aimed to make it organized and sorted according to the height, slope, and the vehicle's speed. The results are as follows. First, our research made use of GIS data and classified the road into 9 different areas according to the height and the slope. Also, road classification being matched to the data of vehicle's speed, it has been shown that those characteristics of different areas have made an influence on vehicle's speed. Secondly, based on the results of the similarity between geographical classification and, vehicle's speed of sorted groups according to the height and the slope, conclusively we have classified as flat, rolling region and mountain. Since our research has made use of vehicle's speed for National Highway, it is not applicable to different functional highways. However, for the highway to be established hereafter, it can be a standard for reflection geographical characteristics.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.65-78
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• 2006

This paper investigates the cost structure ot the Korea and Japan railroad industry with respect to density, scale and scope economies as well as productivity growth rate using a generalized trans)og multiproduct cost function model. The paper then assumes that the Korea and Japan railway companies pi·educe three outputs (incumbent railway passenger-kilometers. Shinkansen passenger-kilometers, ton-kilometers of freight) using four input factors (labor, fuel, maintenance, rolling stock and capital). The specified cost function includes foul other independent variables: track lengths to reflect network effects, two dummies to reflect nation and ownership effects, and time trend as a proxy for technical change. The simultaneous equation system consisting of a cost function and three input share equations is estimated with the Zellner's iterative seemingly unrelated regression. The unbalanced panel data used in the paper, a total of 154 observations. are collected from the annual records of the Korea National Railroad (KNR) for the yews $1977{\sim}2003$, Japan National Railways (JNR) for the years $1977{\sim}1984$. seven Japan Railways (JR's) for the years $1987{\sim}2003$. The findings show that the Korean and Japanese railways exhibit product-specific and overall economies of density but product-specific diseconomies of scale with respect to incumbent railway passenger-kilometers, Shinkansen-kilometers and ton-kilometers. However, the railways experience mild overall economies of scale which result from economies of scope associated with the joint production of incumbent railway/Shinkansen and feight, freight/incumbent railway and Shinkansen except Shinkansen/incumbent railway and freight. In addition, the economies of density and scale in the KNR, JR east, JR central, and JR west companies at the point of the years $1990{\sim}2003$ average is generally analogous to the above results at the point of sample average. There also appear to be economies of ssope associated with the joint Production of the incumbent railway and Shinkansen in JR central but diseconomies of scope in JR East and JR West. The findings also indicate that the productivity growth rate of the privately-owned JR's is larger than that of the government-owned KNR.

• Asia pacific journal of information systems
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• v.20 no.1
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• pp.127-140
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• 2010

The benefit that a consumer derives from the use of a good often depends on the number of other consumers purchasing the same goods or other compatible items. This property, which is known as network externality, is significant in many IT related industries. Over the past few decades, network externalities have been recognized in the context of physical networks such as the telephone and railroad industries. Today, as many products are provided as a form of system that consists of compatible components, the appreciation of network externality is becoming increasingly important. Network externalities have been extensively studied among economists who have been seeking to explain new phenomena resulting from rapid advancements in ICT (Information and Communication Technology). As a result of these efforts, a new body of theories for 'New Economy' has been proposed. The theoretical bottom-line argument of such theories is that technologies subject to network effects exhibit multiple equilibriums and will finally lock into a monopoly with one standard cornering the entire market. They emphasize that such "tippiness" is a typical characteristic in such networked markets, describing that multiple incompatible technologies rarely coexist and that the switch to a single, leading standard occurs suddenly. Moreover, it is argued that this standardization process is path dependent, and the ultimate outcome is unpredictable. With incomplete information about other actors' preferences, there can be excess inertia, as consumers only moderately favor the change, and hence are themselves insufficiently motivated to start the bandwagon rolling, but would get on it once it did start to roll. This startup problem can prevent the adoption of any standard at all, even if it is preferred by everyone. Conversely, excess momentum is another possible outcome, for example, if a sponsoring firm uses low prices during early periods of diffusion. The aim of this paper is to analyze the dynamics of the adoption process in markets exhibiting network effects by focusing on two factors; switching and agent heterogeneity. Switching is an important factor that should be considered in analyzing the adoption process. An agent's switching invokes switching by other adopters, which brings about a positive feedback process that can significantly complicate the adoption process. Agent heterogeneity also plays a important role in shaping the early development of the adoption process, which has a significant impact on the later development of the process. The effects of these two factors are analyzed by developing an agent-based simulation model. ABM is a computer-based simulation methodology that can offer many advantages over traditional analytical approaches. The model is designed such that agents have diverse preferences regarding technology and are allowed to switch their previous choice. The simulation results showed that the adoption processes in a market exhibiting networks effects are significantly affected by the distribution of agents and the occurrence of switching. In particular, it is found that both weak heterogeneity and strong network effects cause agents to start to switch early and this plays a role of expediting the emergence of 'lock-in.' When network effects are strong, agents are easily affected by changes in early market shares. This causes agents to switch earlier and in turn speeds up the market's tipping. The same effect is found in the case of highly homogeneous agents. When agents are highly homogeneous, the market starts to tip toward one technology rapidly, and its choice is not always consistent with the populations' initial inclination. Increased volatility and faster lock-in increase the possibility that the market will reach an unexpected outcome. The primary contribution of this study is the elucidation of the role of parameters characterizing the market in the development of the lock-in process, and identification of conditions where such unexpected outcomes happen.

• Journal of dental hygiene science
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• v.18 no.6
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• pp.327-339
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• 2018

This study aimed to provide basic data for establishing the clinical basis for dental hygienist-led dental hygiene process of care by identifying multiple risk factors for self-support program participants in Gangneung city; we also compared oral health status and behavioral changes through customized oral health care. Four dental hygienists who were evaluated for degree of conformity provided dental hygiene process of care to eight self-support program participants who were selected as having an oral health risk among people in the self-support center. The clinical indicators measured during dental hygiene assessment and evaluation and behavioral changes due to dental hygiene intervention were compared and analyzed. With respect to clinical indicators, at the time of probe, the retention rate of patients with gingival bleeding decreased from 61.4% to 14.7% after intervention (p=0.004). Furthermore, the retention rate of patients with a periodontal pocket >4 mm decreased from 15.6% to 5.8% (p=0.001). The average modified O'Leary index of the patients improved from 23 to 40 (p=0.002). Previously, all eight subjects used the vertical or horizontal method of brushing; after dental hygiene care interventions regarding method and frequency of toothbrushing, use of oral care products, and individual interventions, they started using the rolling or Bass method of toothbrushing. Four of eight subjects reported using interdental toothbrushes after intervention. As a result of applying the change model to the transtheoretical behavior change of the subject, the result of strengthening the health behavior was confirmed. For promotion of oral health by the prevention-centered incremental oral health care system, dental hygienist-led dental hygiene management and maintenance is essential. It is thought that continuous research, such as for feasibility evaluation, cost benefit analysis, and preparation of legal systems, is needed to establish and activate dental hygiene management.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.1
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• pp.35-52
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• 1973

Red Yellow Soils occur very commonly in Korea and constitute the important upland soils of the country which are either presently being cultivated or are suitable for reclaiming and cultivating. These soils are distributed on rolling, moutain foot slopes, and terraces in the southern and western parts of the central districts of Korea, and are derived from granite, granite gneiss, old alluvium and locally from limestone and shale. This report is a summary of the morphology, physical and chemical characteristics of Red Yellow Soils. The data obtained from detailed soil surveys since 1964 are summarized as follows. 1. Red-Yellows Soils have an A, Bt, C profile. The A horizon is dark colored coarse loamy or fine loamy with the thin layer of organic matter. The B horizon is dominantly strong brown, reddish brown or yellowish red, clayey or fine loamy with clay cutans on the soil peds. The C horizon varies with parent materials, and is coarser texture and has a less developed structure than the Bt horizon. Soil depth, varied with relief and parent materials, is predominantly around 100cm. 2. In the physical characteristics, the clay content of surface soil is 18 to 35 percent, and of subsoil is 30 to 90 percent nearly two times higher than the surface soil. Bulk density is 1.2 to 1.3 in the surface soil and 1.3 to 1.5 in the subsoil. The range of 3-phase is mostly narrow with 45 to 50 percent in solid phase, 30 to 45 percent in liquid one, and 5 to 25 percent in gaseous state in the surface soil; and 50 to 60 solid, 35 to 45 percent liquid and less than 15 percent gaseous in the subsoil. Available soil moisture capacity ranges from 10 to 23 percent in the surface soil, and 5 to 16 percent in the subsoil. 3. Chemically, soil reaction is neutral to alkaline in soils derived from limestone or old fluviomarine deposits, and acid to strong acid in other ones. The organic matter content of surface soil varying considerably with vegetation, erosion and cultivation, ranges from 1.0 to 5.0 percent. The cation exchange capacity is 5 to 40 me/100gr soil and closely related to the content of organic matter, clay and silt. Base saturation is low, on the whole, due to the leaching of extractable cations, but is high in soils derived from limestone with high content of lime and magnesium. 4. Most of these soils mainly contain halloysite (a part of kaolin minerals), vermiculite (weathered mica), and illite, including small amount of chlorite, gibbsite, hematite, quartz and feldspar. 5. Characteristically they are similar to Red Yellow Podzolic Soils and a part of Reddish Brown Lateritic Soils of the United States, and Red Yellow Soils of Japan. According to USDA 7th Approximation, they can be classified as Udu Its or Udalfs, and in FAO classification system to Acrisols, Luvisols, and Nitosols.

• The Korean Journal of Quaternary Research
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• v.14 no.1
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• pp.7-31
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• 2000

Quaternary Geological and geophysical investigation was performed at the Eurimji reservoir of Jaechon City in order to interprete depositional environment and genesis of lake sediments. For this purpose, echo sounding, bottom sampling and columnar sampling by drilling on board and GPR survey were employed for a proper field investigation. Laboratory tests cover grain size population analysis, pollen analysis and $^{14}C$ datings for the lake sediments. The some parts of lake bottom sediments anthropogenically tubated and filled several times to date, indicating several mounds on the bottom surface which is difficult to explain by bottom current. Majority of natural sediments were accumulated both as rolling and suspended loads during seasonal flooding regime, when flash flow and current flow are relatively strong not only at bridge area of the western part of Eurimji, connected to stream valley, but at the several conduit or sewage system surrounding the lake. Most of uniform suspend sediments are accumulated at the lake center and lower bank area. Some parts of bottom sediments indicate the existence of turbid flow and mudflow probably due to piezometric overflowing from the lake bottom, the existence of which are proved by CM patterns of the lake bottom sediments. The columnar samples of the lake sediments in ER-1 and ER-3-1 boreholes indicate good condition without any human tubation. The grain size character of borehole samples shows poorly sorted population, predominantly composed of fine sand and muds, varying skewness and kurtosis, which indicate multi-processed lake deposits, very similar to lake bottom sediments. Borehole columnar section, echo sounding and GPR survey profilings, as well as processed data, indicate that organic mud layers of Eurimji lake deposits are deeper and thicker towards lower bank area, especially west of profile line-9. In addition the columnar sediments indicate plant coverage of the Eurimji area were divided into two pollen zones. Arboreal pollen ( AP) is predominant in the lower pollen zone, whreas non-aboreal pollen(NAP) is rich in the upper pollen zone. Both of the pollen zones are related to the vegetation coverage frequently found in coniferous and deciduous broad-leaved trees(mixed forest) surrounded by mountains and hilly areas and prevailing by aquatic or aquatic margin under the wet temperate climate. The $^{14}C$ age of the dark gray organic muds, ER1-12 sample, is 950$\pm$40 years B.P. As the sediments are anthropogenetically undisturbed, it is assumed that the reliability of age is high. Three $^{14}C$ ages of the dark gray organic muds, including ER3-1-8, ER3-1-10, ER3-1-11 samples, are 600$\pm$30 years B.P., 650$\pm$30 years B.P., 800$\pm$40 years B.P. in the descending order of stratigraphic columnar section. Based on the interpretation of depositional environments and formation ages, it is proved that Eurimji reservoir were constructed at least 950$\pm$40 years B.P., the calibrated ages of which ranges from 827 years, B.P. to 866 years B.P. Ancient people utilize the natural environment of the stream valley to meet the need of water irrigation for agriculture in the local valley center and old alluvium fan area.

• Tuberculosis and Respiratory Diseases
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• v.41 no.5
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• pp.521-530
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• 1994

Background : The past studies on prediction formulas of pulmonary function parameters in healthy nonsmoking Korean adults have been performed in relatively small number of subjects and the reported results were restricted on a few parameters. Also there was no systematic investigation into the effect of smoking on pulmonary function parameters in smokers who have no respiratory symptoms. Therefore we attempted to establish prediction formulas of pulmonary function parameters and examined the effect of smoking on pulmonary function parameters. Methods We analyzed the result of parameters derived from the forced expiratory spirogram in 1,067 nonsmoking subjects from June in 1990 to December in 1991. They consisted of 306 males and 761 females and had neither respitatory symptoms nor history of respiratory disease. We derived prediction formulas by multiple linear regression method from their age, heights, and weights in each sex. To examine the effect of smoking on pulmonary function parameters, we classified 383 smoking men into three groups according to the past amount of smoking as follows : i.e. group of smokers who have smoked below 10 pack-years, 10-20 pack-years and above 20 pack-years. Regarding each group of past smoking as an independent dummy variable, we analyzed pulmonary function parameters including nonsmoking men as a baseline by multiple linear regression. We evaluated the smoking effect on pulmonary function parameters according to estimated p-value. Result : 1) Prediction formulas for pulmonary function parameters in each sex were derived. 2) The past smoking less than 10 pack-years does not give any effect on pulmonary function parameters. The past smoking of 10~20 pack-years showed significant negative correlation with $FEV_1$/FVC and FEF 25~75%, and the smoking above 20 pack years showed negative correlation with $FEV_1$ and $FEV_1$/FVC. Conclusion : We have got prediction formulas of pulmonary function parameters which is driven from forced expiratory spirogram in nonsmoking Korean adults by multiple linear regression from age, heights and weights of subjects. The past smoking more than 10 pack-years showed negative correlation with some pulmonary function parameters of airflow obstruction.