• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.267-274
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• 2017

This study discusses the applicability of environmental friendly EVA based butyl rubber self-adhesive waterproof sheet designed to prevent corrosion of large scale pipes used in the water treatment facilities during th water treatment process. The experiments conducted tested the waterproofing sheet's adhesion strength on the steel surface of the pipes and checked for whether the material has the proper response properties against the various environmental conditions. In addition, it the sheet adhered to the steel pipe was to see if the adhesion hold against the water pressure due to the ingress of inflow water. Finally, the waterproofing sheet's adhesion strength was tested on a rusted steel surface to confirm whether the material has the necessary properties to secure stable adhesion strength and prevent corrosion of steel pipes at the same time during the process of installation or maintenance. As a result, the self-adhesive waterproof sheets showed that all attachments in the untreated, long term pressuring, immersion in chemical substance (hydrochloric acid, hypochlorous acid, sodium hydroxide), low temperature ($-20^{\circ}C$) conditions showed a adhesion performance of higher than 1.5N/mm, which is the performance standard of KS F 4934. Also, in the testing to check for the adhesion property against inverse water pressure, it was observed that the adhesion failure did not occur even up to $3.0N/mm^2$ pressure. Also, in the process of assessing the adhesion performance on rusted steel surface, specimens after 12 hours of corrosion treatment was shown to have 2.1N/mm, and specimens after 168 hours of corrosion treatment was shown to have 2.0N/mm adhesion strength performance.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.139-151
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• 2018

The National Base Map construction consists of the regular correction work of dividing the whole country into two regions and carrying out the modification Plotting by aerial photographs every two years as well as the real time updating work of correcting the major change feature within two weeks by the field survey and the As-Built Drawing. In the case of the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS) used for real time updating work of the National base map, the coordinate transformation error is included in the positional error when applied to the National Base Map based on the World Geodetic Reference System as the coordinate system based on the Regional Geodetic Reference System. In addition, National Base Map is registered based on the outline(eaves line) of the building in the Digital Topographic Map, and the Cadastral and Architecture are registered based on the building center line. Therefore, the Building Object management standard is inconsistent. In order to investigate the improvement method, the network RTK survey was conducted directly on a location of the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS) and the problems were analyzed by comparing with the plane plotting position reference in National Base Map. In the case of the general structure with the difference on the Building center line and the eaves line, beside the location information was different also the difference in the ratio of the building object was different between Building center line and the eave. In conclusion, it is necessary to provide the Base data of the double layer of the Building center line and the outline of the building(eaves line) in order to utilize the Building Layout Drawing of Korea Real estate Administration intelligence System(KRAS). In addition, it is necessary to study an organic map update process that can acquire the up-to-dateness and the accuracy at the same time.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.636-644
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• 2019

The purpose of this study was to investigate the callings of nocturnal birds using bioacoustic recording technology to identify species and to analyze the ecological characteristics of each species. Three sites - Seoraksan National Park, National Institute of Ecology, and Mudeungsan National Park - were investigated. The investigation period was from the middle of April 2018 to early March 2019 for Seoraksan national park, from late February of 2018 to the middle of February 2019 for the National Institute of Ecology, and from the middle of February 2018 to the end of August 2018 for Mudeungsan National Park. The main research results are as follows. Firstly, nocturnal bird species identified by the survey included Caprimulgus indicus, Otus sunia, Zoothera aurea, Bubo bubo, and Strix uralensis, 5 species in total. Secondly, the breeding call period of each species was from early May to early August for C. indicus, from early April to the end of September for O. sunia, from early March to early October for Z. aurea, from late September to early February for B. bubo, and from mid-January to early March for S. uralensis. Thirdly, the mating call rhythm was between 16:00 and 10:00 on the following day for all the observed species in the three regions, and the peak time zone was from 20:00 to 06:00 on the following day. Fourthly, there was no correlation between the cumulative call frequency and the precipitation for each species. Fifthly, the mean temperature during the period when the specific calls of nocturnal birds were detected was -4.00 ℃ for S. uralensis, 2.58 ℃ for B. bubo, 13.66 ℃ for Z. aurea, 19.50 ℃ for O. sunia, and 20.77 ℃ for C. indicus. The ANOVA results showed that there was a significant difference in mean temperature for the calling by species and that the mean temperature was S. uralensis, B. bubo, Z. aurea, and O. sunia-C. indicus, in the ascending order, for 4 groups in total. The period of the specific mating calls confirmed by the study is a period in which the frequency of calls was the highest among the periods when the specific calls were detected. Since it is associated with the known mating period of each species, the period of the high frequency of calls confirmed by the bioacoustic monitoring can be regarded as the mating season. This study is meaningful in that it is the early research that has used the bioacoustic recording technology to identify species and ecological characteristics of species of nocturnal birds in Korea.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.171-176
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• 2000

A wastewater treatment pond system was developed for treatment and recycling of dairy cattle excreta of $5\;m^1$ per day. The wastes were diluted by the water used for clearing stalls. The system was composed of three ponds in series. A submerged gas collector for the recovery of methane was installed at the bottom of secondary pond with water depth of 2.4m. This paper deals mainly with performance of methane fermentation of secondary pond which is faclutative one. The average $BOD_5$, SS, TN, and TP concentrations of influent into secondary pond were 49.1, 53.4, 48.6, and 5.3 mg/l, and those of effluent from it were 27.9, 45.7, 30.8, 3.2 mg/l respectively. Methane fermentation of 2.4-meter-deep secondary pond bottom was well established at $16^{\circ}C$ and gas garnered from the collector at that temperature was 80% methane. Literature on methane fermentation of wastewater treatment ponds shows that methane bacteria grow well around $24^{\circ}C$, the rate of daily accumulation and decomposition of sludge is approximately equal at $19^{\circ}C$, and activities of methanogenic bacteria are ceased below $14^{\circ}C$. The good methane fermentation of the pond bottom around $16^{\circ}C$, about $3^{\circ}C$ lower than $19^{\circ}C$, results from temperature stability, anaerobic condition, and neutral pH of the bottom sludge layer. It is recommended that the depth of pond water could be 2.4m. Gas from the collector during active methane fermentation was almost 83% methane, less than 17% nitrogen. Carbon dioxide was less than 1% of the gas, which indicates that carbon dioxide produced in bottom sludges was dissolved in the overlaying water column. Thus a purified methane can be collected and used as energy source. Sludge accumulation on the pond bottom for a nine month period was 1.3cm and annual sludge depth can be estimated to be 1.7cm. Design of additional pond depth of 0.3m can lead to 15 - 20 year sludge removal.

• Sleep Medicine and Psychophysiology
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• v.13 no.1
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• pp.27-32
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• 2006

Objectives: Nasal continuous positive airway pressure (nCPAP) is the treatment of choice and has been shown to reduce the frequency of nocturnal respiratory events, improve sleep architecture, and decrease daytime sleepiness in patients with obstructive sleep apnea syndrome (OSAS). However, little is known about the compliance of nCPAP treatment in Korea. Our objective was to look into the nCPAP compliance and examine the factors influencing it. Methods: We reviewed the records of one hundred and twenty consecutive patients with OSAS referred for nocturnal polysomnography with nCPAP pressure titration during the period of January 1995 through April 1999 to the Seoul National University Hospital. We performed a telephone interview and obtained data from eighty-three patients. Results: In sixty patients who had accepted nCPAP treatment, twenty-six patients (43.3%) were still using nCPAP device, while thirty-four patients (56.7%) stopped using it. Fifteen patients (25%) were using nCPAP device everyday. In thirty-four patients who discontinued nCPAP use, twenty-five patients (73.5%) did within the first three months, and thirty-one (91.2%) within the first year. Significant predictor of long-term nCPAP use was the presence of subjective daytime sleepiness before nCPAP application. Conclusions: Long-term compliance with nCPAP treatment appears to be associated with the presence of subjective daytime sleepiness before nCPAP application. Long-term compliance with nCPAP may be mostly predicted from the usage pattern within the first three months of use.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.61-75
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• 2011

A Geographic Information System(GIS) is a system that captures, stores, analyzes, manages and presents data with reference to geographic location data. In the later 1990s and earlier 2000s it was limitedly used in government sectors such as public utility management, urban planning, landscape architecture, and environmental contamination control. However, a growing number of open-source packages running on a range of operating systems enabled many private enterprises to explore the concept of viewing GIS-based sales and customer data over their own computer monitors. K telecommunication company has dominated the Korean telecommunication market by providing diverse services, such as high-speed internet, PSTN(Public Switched Telephone Network), VOLP (Voice Over Internet Protocol), and IPTV(Internet Protocol Television). Even though the telecommunication market in Korea is huge, the competition between major services providers is growing more fierce than ever before. Service providers struggled to acquire as many new customers as possible, attempted to cross sell more products to their regular customers, and made more efforts on retaining the best customers by offering unprecedented benefits. Most service providers including K telecommunication company tried to adopt the concept of customer relationship management(CRM), and analyze customer's demographic and transactional data statistically in order to understand their customer's behavior. However, managing customer information has still remained at the basic level, and the quality and the quantity of customer data were not enough not only to understand the customers but also to design a strategy for marketing and sales. For example, the currently used 3,074 legal regional divisions, which are originally defined by the government, were too broad to calculate sub-regional customer's service subscription and cancellation ratio. Additional external data such as house size, house price, and household demographics are also needed to measure sales potential. Furthermore, making tables and reports were time consuming and they were insufficient to make a clear judgment about the market situation. In 2009, this company needed a dramatic shift in the way marketing and sales activities, and finally developed a dedicated GIS_based market analysis and sales management system. This system made huge improvement in the efficiency with which the company was able to manage and organize all customer and sales related information, and access to those information easily and visually. After the GIS information system was developed, and applied to marketing and sales activities at the corporate level, the company was reported to increase sales and market share substantially. This was due to the fact that by analyzing past market and sales initiatives, creating sales potential, and targeting key markets, the system could make suggestions and enable the company to focus its resources on the demographics most likely to respond to the promotion. This paper reviews subjective and unclear marketing and sales activities that K telecommunication company operated, and introduces the whole process of developing the GIS information system. The process consists of the following 5 modules : (1) Customer profile cleansing and standardization, (2) Internal/External DB enrichment, (3) Segmentation of 3,074 legal regions into 46,590 sub_regions called blocks, (4) GIS data mart design, and (5) GIS system construction. The objective of this case study is to emphasize the need of GIS system and how it works in the private enterprises by reviewing the development process of the K company's market analysis and sales management system. We hope that this paper suggest valuable guideline to companies that consider introducing or constructing a GIS information system.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.261-271
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• 2016

In the prediction of response of a pile in soil, numerical approaches such as a finite element method are generally applied due to complicate nonlinear behaviors of soils. However, the numerical methods based on the finite elements require heavy efforts in pile and soil modelling and also take long computing time. So their usage is limited especially in the early design stage in which principal dimensions and properties are not specified and tend to vary. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to model and take short computing time. Therefore, if they are validated to be reliable, they would be applicable in predicting responses of a pile in soil, particularly in early design stage. In case of wind turbines regarded in this study, it is required to assess their natural frequencies in early stages, and in this simulation the supporting pile inserted in soil could be replaced with a simplified elastic boundary condition at the bottom end of the wind turbine tower. To do this, analysis for a pile in soil is performed in this study to extract the spring constants at the top end of the pile. The pile in soil can be modelled as a beam on elastic spring by assuming that the soils deform within an elastic range. In this study, it is attempted to predict pile deformations and influence factors for lateral loads by means of the beam-on-spring model. As two example supporting structures for wind turbines, mono pile and suction pile models with different diameters are examined by evaluating their influence factors and validated by comparing them with those reported in literature. In addition, the deflection profiles along the depth and spring constants at the top end of the piles are compared to assess their supporting features.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1994.07a
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• pp.184-215
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• 1994

The Hydrogeologic data of 455 water wells comprising geologic and aquifer test were analyzed to determine hydrogeoloic characteristics of Cheju island. The groundwater of Cheju island is occurred in unconsolidated pyroclastic deposits interbedded in highly jointed basaltic and andesic rocks as high level, basal and parabasal types order unconfined condition. The average transmissivity and specific yield of the aquifer are at about 29,300m$^2$/day and 0.12 respectively. The total storage of groundwater is estimated about 44 billion cubic meters(m$^3$). Average annual precipitation is about 3390 million m$^3$ among which average recharge amount is estimated 1494 million m$^3$ equivalent 44.1% of annual precipitation with 638 million m$^3$ of runoff and 1256 million m$^3$ of evapotranspiration. Based on groundwater budget analysis, the sustainable yield is about 620 million m$^3$(41% of annual recharge)and rest of it is discharging into the sea. The geologic logs of recently drilled thermal water wens indicate that very low-permeable marine sediments(Sehwa-ri formation) composed of loosely cemented sandy sat derived from mainly volcanic ashes, at the 1st stage volcanic activity of the area was situated at the 120$\pm$68m below sea level. And also the other low-permeable sedimentary rock called Segipo-formation which is deemed younger than former marine sediment is occured at the area covering north-west and western part of Cheju at the $\pm$70m below sea level. If these impermeable beds are distributed as a basal formation of fresh water zone of Cheju, most of groundwater in Cheju will be para-basal type. These formations will be one of the most important hydrogeologic boundary and groundwater occurences in the area.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.367-376
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• 2009

Forty specimens of fossil ophiuroids were collected from two formations of the Cenozoic marine deposits, Duho Formation and Hagjeon Formation, Pohang Basin, Korea. A few specimens were three-dimensionally preserved: most of them were remained flattened and articulated. Although a gross morphology is well preserved in some specimens, the details such as disk shape and plates which is the most important diagnostic features were not observed. Most of the arms are disarticulated, and thus arm vertebra, arm spines and/or arm plates are separately preserved. Only an oral side is recognized in an attached specimens because crossing arms into disk are clearly visible. It is, thus almost impossible to identify Korean ophiuroid fossils as a species level or even a genus level. The fossils were classified into 3 groups by gross morphology of disk and arm, and architecture of vertebra. The most abundant fossils (32 specimens), were found only in the Hagjeon Formation. The majority of specimens are partially disarticulated, having only proximal and median portions of their arms preserved. Arm plates are disarticulated from arm vertebra: most of them show structure of arm vertebra. It has long and well-preserved arm spines, and large tentacle pore. Some specimens (4 specimens) from the Duho Formation is characterized by short and conical arm spines, and well-developed arm plates. Lateral arm plates are small in compared to dorsal and ventral arm plates. The others (4 specimens) is poor in preservation state showing circular oral disk and relatively short sinuous arms. No arm plates are either identified.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.45-52
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• 2015

With the rising interest in the environment, more attention on ecological restoration for damaged slope surface to restore its original state has been drawn. Generally, the most useful method is vegetation based spray work. This method uses green soil including sewage sludge, sawdust, paper sludge, and weathered granite soil. However, because there are neither accurate information nor test values about green soil, green soil is often lost by environmental factors such as rainfalls and strong winds. To solve the problem of green soil, it is necessary to prepare design standards about green soil, and conduct studies to deal with green soil loss in consideration of various variables including basic material property, soil quality of slope surface, and weather. This study was conducted in the mixture of green soil and eco-friendly soil stabilizer. With green soil, basic material property test and compaction test were conducted for the analysis on the basic characteristics of green soil. In the mixture with soil stabilizer at a certain ratio, we conducted shear strength test depending on the ratio in order to analyze the maximum shear strength, cohesion and the change in internal friction angles. Furthermore, in the mixture ratio of green soil and soil stabilizer, which is the same as the ratio in the shear strength test, an inclination of slope surface was made in laboratory for the analysis on erosion and germination rate. Finally, this study evaluated the most effective and economic mixing ratio of soil stabilizer to cope with neighboring environmental factors. According to the test, the shear strength of green soil increased up to 51% rely onto the mixing ratio of and a curing period, and its cohesion and internal friction angle also gradually increases. It is judged that the mixture of soil stabilizer was effective in improving shear strength and thereby increased the stability of green soil.