• Journal of Applied Reliability
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• v.9 no.1
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• pp.37-45
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• 2009

Recently mechanical watt-hour meters are being replaced by electronic watt-hour meters. The replacement period of mechanical watt-hour meters is 7 years. This period is based on long term historical data. The replacement period of electronic watt-meters is also 7 years. This period is determined using the replacement period of mechanical watt-hour meters. However lifetime of mechanical watt-hour meters is different from the lifetime of electronic meters. In order to determine desirable replacement period of electronic watt-hour meters, accelerated life tests of major components in electronic watt-hour meters were performed. The test results showed that LCD was the component which had the shortest lifetime. In this paper, lifetime of electronic watt-hour meters manufactured by 3 company was estimated and life test standard for LCD was developed.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.582-594
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• 2005

The under-registration of water meters of 20mm to 50mm in diameter, installed in Seoul city, was estimated by random sample method. The sample sites and sampled meters were selected for the measurements of flow rates and accuracy tests, respectively. The measurement of flow rates was conducted for 20mm to 50mm meters for about 20 days per site using flow meters and data loggers. The under-registration of 20mm, 25mm, 32mm, 40mm, and 50mm meters was observed as 3.96%, 1.10%, 2.47%, 4.04%, and 1.04%, respectively. The under-registration might be increased more or less as malfunction and failure of the sampled meters was not considered. In this study the under-registration of 20mm, 25mm, 32mm, 40mm, and 50mm meters was accurately estimated on the basis of the investigation data. The estimation of under-registration of water meters, one of the basic figures in water industry, contributed to accurate calculation of leakage, water supply and consumption, and strategic planning to reduce the unaccounted-for water.

• Atmosphere
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• v.28 no.1
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• pp.69-83
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• 2018

Most of the researches on fog in South Korea have been done based on the naked-eye observation but the number of observation sites is just 22. Considering the localities of fog and various durations, it is essential to utilize more than 250 visibility meters that measure visibility every minute. In this study, the visibility characteristics of visibility meters were compared with that of the naked-eye observation using one year data, 2016, and radiation fog and advection fog cases were analyzed in detail. The concordance rate of the two data set was 0.96~0.97, but discordance rate was 0.19~0.47. In general, visibility meters observed fog more frequently than naked-eye. The correlation between two data sets is clearly dependent on the visibility and geographic locations (fog/thick fog (< 100 m) of inland: 0.86/0.61; fog/thick fog: 0.65/0.73 of island/coastal site). In both fog cases, the fog events observed by naked-eye were consistently detected by visibility meters, and visibility meters clearly well detected very short fog/thick fogs. Formation and dissipation time of fog for the fog cases were similar but fog duration by visibility meters was shorter because of exclusion of temporary dissipated time. In addition, the visibility meters showed a detailed distribution of fog events that occurred simultaneously over South Korea. It would be useful to analyze the spatial and temporal characteristics of, in particular, thick fog using visibility meters. However, more works are needed for the filtering criteria for analyzing fog using visibility meters alone.

• Journal of the Korean housing association
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• v.16 no.2
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• pp.19-25
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• 2005

This paper call attention to the characteristics of apartment unit plans as to the outdoor adjacency methods. My arguments will attempt to investigate spatial composition and each room sizes of the unit plans. So far, very little has been done in this direction. I will limits myself to study 573 plans which have been designed from 1996 till 2003. What emerges from this analysis is that these samples divided 3 types derived from the outdoor adjacency methods. Type 1 limits itself to 39 square meters unit plans. Type 2 was distributed from 49 square meters to 200 square meters with the exception of 100-110 square meters. And, type 3 ranges from 59 to 160 square meters. Therefore, it could be profitable each room's environmental condition (daylight, ventilation and etc) and diverse apartment building types to design in extent 49-160 square meters.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.1
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• pp.1413-1419
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• 1968

Yochon reservoir was consturcted with an original storage capacity of 202.7 chung-meters. This reservoir receives the water from watershed area of 933.0 chungbo and has irrigated area of 478.0 chungbo. In 1967 a detailed capacity survey of this reservoir was carried out by a new depth-recorder under the scheme of reservoir sedimentation of Agricultural Engineering Research Center. Significant findings are 1. The capacity of the reservoir for the water storage has been reduced by 8.9%(18.066 chung-meters out of the 202.7 chung-meters) since its construction, a period of just 39.0 years. 2. The sediment accumulation in the reservoir represents an average annual soil loss of 0.496mm depth(0.463 chung-meters) of soil from the watershed area of 933.0 chungbo. Eventually the capacity of the reservoir for the water storage will be reducing by about 25%(50.7 chung-meters out of the 202.7 chung-meters)in one hundred years since its construction. We have to set up controlling projects for those reservoir protections from the sediment, soil loss, and other failures. The depth recorder is very useful, convenient, and accurate machine for surveys of reservoir capacity and other river surveys.

• 한국해양학회지
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• v.10 no.2
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• pp.57-66
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• 1975

Structure of thermocline, characteristics of stability and intensity of vertical transfer have been studied with hourly oceanographic data in each layers on Line 207 from 1968 to 1969. It is found that a typical thermocline is formed at depths of 10 to 50 meters in summer and early autumn and its core is located near depths of 25 meters. The maximum diffusion coefficient of vertical turbulent is found to be 140$\textrm{cm}^2$/sec at the surface layer(i.e., 0-10 meters), while the minimum is 5$\textrm{cm}^2$/sec at depths of 25 meters, consistent with characteristics of stability and structure of thermocline layers. Our computed diffusion coefficient and stability indicate that the mixing hardly takes place below depths of 80 meters during summer and early autumn, but for the rest of the season mixing could move up to the depth of 50 meters. It appears that the Western Channel of the Korea Strait consist of three different water masses during summer and autumn, and for the rest of the season, two kinds are present.

• Korean Journal of Environment and Ecology
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• v.21 no.2
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• pp.141-148
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• 2007

To investigate the forest community structure ranging from 200 meters to 1,350 meters above sea level at Donnaeko valley of Mt. Hallasan in 2006, 15 plots were surveyed. According to the classification analysis by TWINSPAN, the plant communities were divided into five groups of Castanopsis sieboidii community, Castanopsis sieboldii - Quercus acuta community, mixed forest, Carpinus laxiflora - Quercus serrata community and deciduous broad-leaved forest. 22 species of evergreen broad-leaved trees such as Castanopsis sieboldii, Quercus acuta, Distylium racemosum, Camellia japonica, Eurya japonica, Ligustrum lucidum, Ilex crenata, Daphnipyllum macropodum, etc. were growing at Donnaeko valley. According to the attitudinal distribution of evergreen broad-leaved trees, Castanopsis sieboidii was a dominant species distributed from 200 meters to 350 meters above sea level, Castanopsis sieboldii and Quercus acuta were dominant species distributed from 400 meters to 600 meters above sea level and Quercus acuta was a dominant species distributed from 660 meters to 700 meters above sea level. Ilex crenata, Daphniphyllum macropodum, Elaeagnus glabra were distributed up to 1,350 meters above sea level in Donnaeko.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.1
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• pp.36-46
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• 1997

Recently, The rural-pocket parks in Korea have been constructed for the recreation activities of the rural residents. The purpose of this study is to suggest planning guidelines focused on the minimum size. The methods used in this study are surveying the satisfaction of rural residents, analyzing the size of Rural-Pocket Parks recently constructed, and comparing with pocket parks in Seoul. The major findings of this study can be summarized as follows : 1) The average size of rural-pocket park in Kyung-Ki province is 650square meters per village and 2.19square meters per capita. and the relation between current rural-pocket park size and the number of household can be described as The current Size of Rural-Pocket Park = 7 ㎡${\times}$ Number of Households 2) The minimum size based on the rural residents'satisfaction is 633square meters at the 62 households level, and can be described as The Size of Rural-Pocket Park = 10㎡ ${\times}$ Number of Households 3) The most required activities by the rural residents are relaxation, children's playing and sports. and the most required facilities are ‘Jung-Ja’and ‘Combined Playing facility’. 4) The size required to include the basic recreational facilities at the level of household 20, 50, 100 are 132square meters. 386square meters, 633square meters respectively. The size per household is 7square meters and can be described as 5) As conclusion about 7square meters per household is recommended for the minimum size of rural-pocket park. and at least 140square meters is required as minimum size of rural-pocket park for the basic recreational facilities. The minimum Size of Rural-Pocket Park=㎡${\times}$Number of Households

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.729-734
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• 2011

In this paper, e-Meters middleware and applications using standardized middleware in the EPCglobal is suggested. An standardized middleware of the EPCglobal is designed to manage as a form of SCM and other logistics. In order to support a variety of services using RFID-based, the system must be able to support each protocol. The main features of e-Meters middleware is consist of information status and delivery, distributed database processing, event data analysis, and handling. To operate real time e-Meters system information, The realized middleware is configured to process the results of data collection.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.6
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• pp.111-125
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• 2010

There is a growing interest in "smart grid" technology, especially after the government recently announced "low-carbon green-growth industry" project. A smart grid uses "smart meters", which can be deployed in any power-consuming places like homes and factories. It has been shown that smart meters have several security weaknesses. There is, however, no protection profile available for smart meters, which means that safety with using them is not guaranteed at all. This paper analyzes vulnerabilities of smart meters and the relevant attack methods, thereby deriving the security functions and requirements for smart meters. Finally, we propose a protection profile based on Common Criterion v3.l for smart meters.