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Utilization of meiobenthos for pollution monitoring in the Gamak Bay, Korea (가막만의 중형저서생물을 활용한 오염모니터링)

  • KIM Dong-Sung;JE Jong-Geel;SHIN Sang-Ho
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.33 no.4
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    • pp.307-319
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    • 2000
  • Community structure (seasonal fluctuation), taxon diversity, nematodes/benthic harpacticoids and nematodes/kinorhynchs ratios of meiobenthos were studied in the Gamak Bay, Korea. A series of samplings were carried out from April 1997 to May 1999. Meiobenthic organisms was collected by van Veen grab and three subcores of 34 mm in internal diameter were taken from each sediment sample. The total density of meiobenthos in each seasons was found to be the highest in May 1999, and the lowest in December 1998. Total density of meiobenthos at each station was the highest at Station 9 in May 1999 ($2,218 inds./10 cm^2$) and the lowest at Station 3 in December 1998 ($2 inds./10 cm^2$). The Gamak Bay seemed to have an individual number increased from the inner toward the outer stations. The highest number of meiobenthos was observed on 0.125 and 0.063 mm mesh size. In every season, over $80{\%}$ of the meiobenthos was composed of only four groups: nematodes, benthic harpacticoids, sarcomastigophorans and nauplius larvae of crustaceans. Seasonal fluctuation of meiobenthos was also studied. The nematodes/benthic harpacticoids(nematodes/kinorhynchs) ratios were studied as an index of pollution monitoring for benthic ecosystem at each station in each season. The value of nematodes/benthic harpacticoids ratio was the highest at the inner stations and the lowest at the outer stations in the Gamak Bay. Taxon diversity (H') was the highest at the outer stations and the lowest at the inner stations in the Gamak Bay. The value of nematodes/benthic harpacticoids ratio significantly increased from the outer toward the inner stations, whereas the taxon diversity (H') significantly increased from the inner toward the outer stations in Gamak Bay.

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Spatial Changes in the Business Organization of Retailing in the Seoul Metropolitan Area (首都圈地域 小賣業 經營의 空間的 變容)

  • Han, Ju-Seong
    • Journal of the Korean Geographical Society
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    • v.31 no.1
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    • pp.19-37
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    • 1996
  • This paper aims at examining the regional difference of changes in the business organization of retailing in the Seoul metropolitan areas, as an attempt to understand regional structure of retailing within metropolitan areas showing the trend of suburbanization. On the national level, retail sales have concentrated on the large metropolitan areas, especially on the Seoul metropolitan area, with the concentration of population and income. Within metropolitan areas, the suburbanization of retailing has made the larger structure of retail and multi-store retail appeared. In order to confirm such phenomenon, this paper is to analyze and to compare the industrial composition of retailing using industry data of 1979 and 1991. And this paper is to analyze the regional changes in the characteristics of business organization of retailing, with the index including the percentages of establishments with less than under four employees, juridical establishments, employees of ordinary times, and the annual sales per establishment of detailing. The characteristics of business organization of retailing in analyzed by principal components analysis, and the types with component in each district (city, county, ward) is analyzed by cluster analysis(Ward method). The data of 1979 were obtained from the statistics in the Census of Wholesale and Retail Trade published by the National Bureau of Statistics of Economic Planning Board, and that of 1991 were obtained from the statistics in the Report on Establishment Census (Vol.3 Wholesale and Retail Trade) published by the National Statistics Office. The following are resultant findings. 1. In Seoul metropolitan area, changes in the industrial composition of retailing with annual sales from, 1979 to 1991 show very higher composition rates of 'general merchandise stores' and 'retailing of personal transport equipment and gasoline service stations', but comparatively lower composition rates of 'retailing of food, beverages and tobacco', 'retailing of textiles, clothing, footwear and apparel accessaries', 'general retail trade, n.e.c.',and 'retailing of household fuel'. 2. The characteristics of business organization of retailing in Seoul metropolitan area presents the prevailence of small, personal business organization and especially larger employees of ordinary times. 3. Business components of retailing by principal components analysis in Seoul metropolitan area are follows: 1 All retaining industries are larger business scale. 2. Larger business take the 'retailing of taxtiles, clothing, footwear and apparel accessories', 'retailing of furniture, home furnishing and equipment', and 'retailing of jewellery and watches' is main characteristic legal organization and employees of ordinary times. 4. Types changes in business organization of retailing in Seoul metropolitan area represent legal organization and employees of ordinary times taking the 'retailing of textiles, clothing, footwear and apparel accessories', 'retailing of furniture, home furnishing and equipment',and 'retailing of jewellery and equipment', and 'retailing of jewellery and watches', and legal organization taking 'general retail trade, n.e.c.' in 1979. All retailing industries are changed into larger business scale, in 1991. These phenomena of business changes appeared southeastern regions in Kyunggi-do(province). And larger business scale taking the 'retailing of textiles, clothing, footwear and apparel accessories', 'retailing of jewellery and watches', and 'general retail trade, n.e.c.; are appeared in the legal organization in 1979. 'Retailing of personal transport equipment and gasoline service stations' are appeared in employees of ordinary times in 1991. These phenomena of business changes in appeared in eastern and northern regions in Kyunggi-do. 5. Changes in the business organization of retailing in Seoul metropolitan area is appeared in legal organization and employees of ordinary times for some industries in 1979, larger business scale of retailing and employees of ordinary times in 'retailing of personal transport equipment and gasoline service stations' are the characteristics in 1991.

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Temporal and Spatial Variability of Phytoplankton Communities in the Nakdong River Estuary and Coastal Area, 2011-2012 (2011-2012년 낙동강 하구 및 연안역에서 식물플랑크톤 군집의 시·공간적 변화)

  • Chung, Mi Hee;Youn, Seok-Hyun
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.18 no.4
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    • pp.214-226
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    • 2013
  • To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

A Study on Characteristics of the Vegetation Structures and Vegetation Landscape Management in the Cultural Landscape Forest of Unmun Temple, Cheongdo-gun, Korea (청도군 운문사 문화경관림 식생구조 특성과 식생경관 관리방안 연구)

  • Lee, Do-I;Han, Bong-Ho;Kwak, Jeong-In
    • Journal of the Korean Institute of Landscape Architecture
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    • v.47 no.3
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    • pp.81-92
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    • 2019
  • This study was conducted to establish vegetation structure characteristics and vegetation management plan of the cultural landscape forests located around Unmun Temple in Cheongdo-gun and to provide the basic data needed to manage the cultural landscape forests. The landscape characteristics are analyzed in two perspectives including the landscape as viewed from inside and outside of Unmun Temple and eight landscape views are selected. Main views are Pinus densiflora forest and Abies holophylla forest around Unmun Temple. As a result of the survey of existing vegetation around Cheongdo-gun Unmun Temple, P. densiflora forests and P. densiflora-A. holophylla forests are widely distributed, occupying 79.2% of the forest. The plant community structure was classified into seven types according to the three topographic characteristics, flat forests, slope forests, and lower forests, Which were divided into a total of 30 survey plots and the average relative importance percentage was determined. The P. densiflora community on the flat are dominated by Carpinus tschonoskii in Under-canopy. The P. densiflora-A. holophylla community on the flat had a relatively high rate of domination in the shrubs. There were no competing species for the A. holophylla community on the plat. The large standard P. densiflora and the small standard P. densiflora were expected to be confined by P. serrulata var. pubescens and the Quercus variabilis on the slopes. The managed P. densiflora community had a relatively high rate of P. densiflora domination in the shrubs. The P. densiflora community on the lowland was dominated by Styrax japonicus and P. serrulata var. pubescens. The Shannon species diversity index was 0.2360 to 1.4088. The results of the correlation analysis with P. densiflora, A. holophylla and other species were P. densiflora had negative correlation with Acer mono, Corylus heterophylla var. heterophylla, Zelkova serrata and A. holophylla, and A. holophylla have negative correlation with S. japonicus and P. densiflora. Landscape characteristics and plant community structures are analyzed to propose management methods of maintaining and restoring The P. densiflora and A. holophylla cultural forest landscapes around Unmun Temple.

An Evaluation of Allowable Bearing Capacity of Weathered Rock by Large-Scale Plate-Bearing Test and Numerical Analysis (대형평판재하시험 및 수치해석에 의한 풍화암 허용지지력 평가)

  • Hong, Seung-Hyeun
    • Journal of the Korean Geotechnical Society
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    • v.38 no.10
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    • pp.61-74
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    • 2022
  • Considering that the number of cases in which a structure foundation is located on weathered rock has been increasing recently, for adequate design bearing capacity of a foundation on weathered rock, allowable bearing capacities of such foundations in geotechnical investigation reports were studied. With reference to the study results, the allowable bearing capacity of a foundation on weathered rock was approximately 400-700 kN/m2, with a large variation, and was considered a conservative value. Because the allowable bearing capacity of the foundation ground is an important index in determining the foundation type in the early design stage, it can have a significant influence on the construction cost and period according to the initial decision. Thus, in this study, six large-scale plate-bearing tests were conducted on weathered rock, and the bearing capacity and settlement characteristics were analyzed. According to the test results, the bearing capacities from the six tests exceeded 1,500 kN/m2, and it shows that the results are similar with the one of bearing capacity formula by Pressuremeter tests when compared with the various bearing capacity formula. In addition, the elastic modulus determined by the inverse calculation of the load-settlement behavior from the large-scale plate-bearing tests was appropriate for applying the elastic modulus of the Pressuremeter tests. With consideration of the large-scale plate-bearing tests in this study and other results of plate-bearing tests on weathered rock in Korea, the allowable bearing capacity of weathered rock is evaluated to be over 1,000 kN/m2. However, because the settlement of the foundation increases as the foundation size increases, the allowable bearing capacity should be restrained by the allowable settlement criteria of an upper structure. Therefore, in this study, the anticipated foundation settlements along the foundation size and the thickness of weathered rocks have been evaluated by numerical analysis, and the foundation size and ground conditions, with an allowable bearing capacity of over 1,000 kN/m2, have been proposed as a table. These findings are considered useful in determining the foundation type in the early foundation design.

Synthesis and Structural Study of Extraframework ZrI6Tl119+ Cationic Cluster in Zeolite A (제올라이트 A 동공 내 비골격 ZrI6Tl119+ 양이온 클러스터의 합성과 구조 연구)

  • Hyeon Seung, Lim;Jong Sam, Park;Cheol Woong, Kim;Woo Taik, Lim
    • Korean Journal of Mineralogy and Petrology
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    • v.35 no.4
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    • pp.447-455
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    • 2022
  • Fully dehydrated Tl12-LTA (|Tl12|[Si12Al12O48]-LTA,Tl12-A) was treated with 6.0×103 Pa of ZrI4 (g) at 623 K for 72 hr under anhydrous conditions. The crystal structure of product, |Zr0.25I1.5Tl12|[Si12Al12O48]-LTA, was determined by single-crystal crystallography using synchrotron X-radiation in the cubic space group Pm3m (a = 12.337(2) Å). It was refined using all data to the final error index (for the 712 unique reflections for which Fo> 4σ(Fo) R1/wR2= 0.055/0.189. In this structure, octahedral ZrI62- ions center about 25% of the large cavities (Zr-I = 2.91(4) Å). Each coordinates to eight Tl+ ions and they are further bridged by Tl+ ions in the planes of 8-rings to form a cubic three-dimensional ZrI6Tl119+ cationic cluster. About 1.5 Tl+ ions per unit cell moved to deeper side of sodalite cavity after reaction with ZrI4(g). The remaining Tl+ ions occupy well-established cation positions near 6- and 8-rings.

Smart Store in Smart City: The Development of Smart Trade Area Analysis System Based on Consumer Sentiments (Smart Store in Smart City: 소비자 감성기반 상권분석 시스템 개발)

  • Yoo, In-Jin;Seo, Bong-Goon;Park, Do-Hyung
    • Journal of Intelligence and Information Systems
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    • v.24 no.1
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    • pp.25-52
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    • 2018
  • This study performs social network analysis based on consumer sentiment related to a location in Seoul using data reflecting consumers' web search activities and emotional evaluations associated with commerce. The study focuses on large commercial districts in Seoul. In addition, to consider their various aspects, social network indexes were combined with the trading area's public data to verify factors affecting the area's sales. According to R square's change, We can see that the model has a little high R square value even though it includes only the district's public data represented by static data. However, the present study confirmed that the R square of the model combined with the network index derived from the social network analysis was even improved much more. A regression analysis of the trading area's public data showed that the five factors of 'number of market district,' 'residential area per person,' 'satisfaction of residential environment,' 'rate of change of trade,' and 'survival rate over 3 years' among twenty two variables. The study confirmed a significant influence on the sales of the trading area. According to the results, 'residential area per person' has the highest standardized beta value. Therefore, 'residential area per person' has the strongest influence on commercial sales. In addition, 'residential area per person,' 'number of market district,' and 'survival rate over 3 years' were found to have positive effects on the sales of all trading area. Thus, as the number of market districts in the trading area increases, residential area per person increases, and as the survival rate over 3 years of each store in the trading area increases, sales increase. On the other hand, 'satisfaction of residential environment' and 'rate of change of trade' were found to have a negative effect on sales. In the case of 'satisfaction of residential environment,' sales increase when the satisfaction level is low. Therefore, as consumer dissatisfaction with the residential environment increases, sales increase. The 'rate of change of trade' shows that sales increase with the decreasing acceleration of transaction frequency. According to the social network analysis, of the 25 regional trading areas in Seoul, Yangcheon-gu has the highest degree of connection. In other words, it has common sentiments with many other trading areas. On the other hand, Nowon-gu and Jungrang-gu have the lowest degree of connection. In other words, they have relatively distinct sentiments from other trading areas. The social network indexes used in the combination model are 'density of ego network,' 'degree centrality,' 'closeness centrality,' 'betweenness centrality,' and 'eigenvector centrality.' The combined model analysis confirmed that the degree centrality and eigenvector centrality of the social network index have a significant influence on sales and the highest influence in the model. 'Degree centrality' has a negative effect on the sales of the districts. This implies that sales decrease when holding various sentiments of other trading area, which conflicts with general social myths. However, this result can be interpreted to mean that if a trading area has low 'degree centrality,' it delivers unique and special sentiments to consumers. The findings of this study can also be interpreted to mean that sales can be increased if the trading area increases consumer recognition by forming a unique sentiment and city atmosphere that distinguish it from other trading areas. On the other hand, 'eigenvector centrality' has the greatest effect on sales in the combined model. In addition, the results confirmed a positive effect on sales. This finding shows that sales increase when a trading area is connected to others with stronger centrality than when it has common sentiments with others. This study can be used as an empirical basis for establishing and implementing a city and trading area strategy plan considering consumers' desired sentiments. In addition, we expect to provide entrepreneurs and potential entrepreneurs entering the trading area with sentiments possessed by those in the trading area and directions into the trading area considering the district-sentiment structure.

Performance Improvement on Short Volatility Strategy with Asymmetric Spillover Effect and SVM (비대칭적 전이효과와 SVM을 이용한 변동성 매도전략의 수익성 개선)

  • Kim, Sun Woong
    • Journal of Intelligence and Information Systems
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    • v.26 no.1
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    • pp.119-133
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    • 2020
  • Fama asserted that in an efficient market, we can't make a trading rule that consistently outperforms the average stock market returns. This study aims to suggest a machine learning algorithm to improve the trading performance of an intraday short volatility strategy applying asymmetric volatility spillover effect, and analyze its trading performance improvement. Generally stock market volatility has a negative relation with stock market return and the Korean stock market volatility is influenced by the US stock market volatility. This volatility spillover effect is asymmetric. The asymmetric volatility spillover effect refers to the phenomenon that the US stock market volatility up and down differently influence the next day's volatility of the Korean stock market. We collected the S&P 500 index, VIX, KOSPI 200 index, and V-KOSPI 200 from 2008 to 2018. We found the negative relation between the S&P 500 and VIX, and the KOSPI 200 and V-KOSPI 200. We also documented the strong volatility spillover effect from the VIX to the V-KOSPI 200. Interestingly, the asymmetric volatility spillover was also found. Whereas the VIX up is fully reflected in the opening volatility of the V-KOSPI 200, the VIX down influences partially in the opening volatility and its influence lasts to the Korean market close. If the stock market is efficient, there is no reason why there exists the asymmetric volatility spillover effect. It is a counter example of the efficient market hypothesis. To utilize this type of anomalous volatility spillover pattern, we analyzed the intraday volatility selling strategy. This strategy sells short the Korean volatility market in the morning after the US stock market volatility closes down and takes no position in the volatility market after the VIX closes up. It produced profit every year between 2008 and 2018 and the percent profitable is 68%. The trading performance showed the higher average annual return of 129% relative to the benchmark average annual return of 33%. The maximum draw down, MDD, is -41%, which is lower than that of benchmark -101%. The Sharpe ratio 0.32 of SVS strategy is much greater than the Sharpe ratio 0.08 of the Benchmark strategy. The Sharpe ratio simultaneously considers return and risk and is calculated as return divided by risk. Therefore, high Sharpe ratio means high performance when comparing different strategies with different risk and return structure. Real world trading gives rise to the trading costs including brokerage cost and slippage cost. When the trading cost is considered, the performance difference between 76% and -10% average annual returns becomes clear. To improve the performance of the suggested volatility trading strategy, we used the well-known SVM algorithm. Input variables include the VIX close to close return at day t-1, the VIX open to close return at day t-1, the VK open return at day t, and output is the up and down classification of the VK open to close return at day t. The training period is from 2008 to 2014 and the testing period is from 2015 to 2018. The kernel functions are linear function, radial basis function, and polynomial function. We suggested the modified-short volatility strategy that sells the VK in the morning when the SVM output is Down and takes no position when the SVM output is Up. The trading performance was remarkably improved. The 5-year testing period trading results of the m-SVS strategy showed very high profit and low risk relative to the benchmark SVS strategy. The annual return of the m-SVS strategy is 123% and it is higher than that of SVS strategy. The risk factor, MDD, was also significantly improved from -41% to -29%.

Memory Organization for a Fuzzy Controller.

  • Jee, K.D.S.;Poluzzi, R.;Russo, B.
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1993.06a
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    • pp.1041-1043
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    • 1993
  • Fuzzy logic based Control Theory has gained much interest in the industrial world, thanks to its ability to formalize and solve in a very natural way many problems that are very difficult to quantify at an analytical level. This paper shows a solution for treating membership function inside hardware circuits. The proposed hardware structure optimizes the memoried size by using particular form of the vectorial representation. The process of memorizing fuzzy sets, i.e. their membership function, has always been one of the more problematic issues for the hardware implementation, due to the quite large memory space that is needed. To simplify such an implementation, it is commonly [1,2,8,9,10,11] used to limit the membership functions either to those having triangular or trapezoidal shape, or pre-definite shape. These kinds of functions are able to cover a large spectrum of applications with a limited usage of memory, since they can be memorized by specifying very few parameters ( ight, base, critical points, etc.). This however results in a loss of computational power due to computation on the medium points. A solution to this problem is obtained by discretizing the universe of discourse U, i.e. by fixing a finite number of points and memorizing the value of the membership functions on such points [3,10,14,15]. Such a solution provides a satisfying computational speed, a very high precision of definitions and gives the users the opportunity to choose membership functions of any shape. However, a significant memory waste can as well be registered. It is indeed possible that for each of the given fuzzy sets many elements of the universe of discourse have a membership value equal to zero. It has also been noticed that almost in all cases common points among fuzzy sets, i.e. points with non null membership values are very few. More specifically, in many applications, for each element u of U, there exists at most three fuzzy sets for which the membership value is ot null [3,5,6,7,12,13]. Our proposal is based on such hypotheses. Moreover, we use a technique that even though it does not restrict the shapes of membership functions, it reduces strongly the computational time for the membership values and optimizes the function memorization. In figure 1 it is represented a term set whose characteristics are common for fuzzy controllers and to which we will refer in the following. The above term set has a universe of discourse with 128 elements (so to have a good resolution), 8 fuzzy sets that describe the term set, 32 levels of discretization for the membership values. Clearly, the number of bits necessary for the given specifications are 5 for 32 truth levels, 3 for 8 membership functions and 7 for 128 levels of resolution. The memory depth is given by the dimension of the universe of the discourse (128 in our case) and it will be represented by the memory rows. The length of a world of memory is defined by: Length = nem (dm(m)+dm(fm) Where: fm is the maximum number of non null values in every element of the universe of the discourse, dm(m) is the dimension of the values of the membership function m, dm(fm) is the dimension of the word to represent the index of the highest membership function. In our case then Length=24. The memory dimension is therefore 128*24 bits. If we had chosen to memorize all values of the membership functions we would have needed to memorize on each memory row the membership value of each element. Fuzzy sets word dimension is 8*5 bits. Therefore, the dimension of the memory would have been 128*40 bits. Coherently with our hypothesis, in fig. 1 each element of universe of the discourse has a non null membership value on at most three fuzzy sets. Focusing on the elements 32,64,96 of the universe of discourse, they will be memorized as follows: The computation of the rule weights is done by comparing those bits that represent the index of the membership function, with the word of the program memor . The output bus of the Program Memory (μCOD), is given as input a comparator (Combinatory Net). If the index is equal to the bus value then one of the non null weight derives from the rule and it is produced as output, otherwise the output is zero (fig. 2). It is clear, that the memory dimension of the antecedent is in this way reduced since only non null values are memorized. Moreover, the time performance of the system is equivalent to the performance of a system using vectorial memorization of all weights. The dimensioning of the word is influenced by some parameters of the input variable. The most important parameter is the maximum number membership functions (nfm) having a non null value in each element of the universe of discourse. From our study in the field of fuzzy system, we see that typically nfm 3 and there are at most 16 membership function. At any rate, such a value can be increased up to the physical dimensional limit of the antecedent memory. A less important role n the optimization process of the word dimension is played by the number of membership functions defined for each linguistic term. The table below shows the request word dimension as a function of such parameters and compares our proposed method with the method of vectorial memorization[10]. Summing up, the characteristics of our method are: Users are not restricted to membership functions with specific shapes. The number of the fuzzy sets and the resolution of the vertical axis have a very small influence in increasing memory space. Weight computations are done by combinatorial network and therefore the time performance of the system is equivalent to the one of the vectorial method. The number of non null membership values on any element of the universe of discourse is limited. Such a constraint is usually non very restrictive since many controllers obtain a good precision with only three non null weights. The method here briefly described has been adopted by our group in the design of an optimized version of the coprocessor described in [10].

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A Structural Relationship among Job Requirements, Job Resources and Job Burnout, and Organizational Effectiveness of Private Security Guards (민간경비원의 직무요구 직무자원과 소진, 조직유효성의 구조적 관계)

  • Kim, Sung-Cheol;Kim, Young-Hyun
    • Korean Security Journal
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    • no.48
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    • pp.9-33
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    • 2016
  • The purpose of the present study was to find out cause-and-effect relationship between job requirements and job resources, with job burnout as a mediator variable, and the effects of these variables on organizational effectiveness. The population in the present study was private security guards employed by 13 private security companies in Seoul and Gyeonggi-do areas, and a survey was conducted on 500 security guards selected using purposive sampling technique. Out of 460 questionnaires distributed, 429 responses, excluding 31 outliers or insincere responses, were used for data analysis. For analysis, data were coded and entered into SPSS 18.0 and AMOS 18.0, which were used to analyze the data. Descriptive analyses were performed to find out sociodemographic characteristics of the respondents. The exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to test the validity of the measurement tool, and the Cronbach's Alpha coefficients were calculated to test the reliability. To find out the significance of relationships among variables, Pearson's correlation analysis was performed. Covariance Structure Analysis (CSA) was performed to test the relationship among latent factors of a model for job requirements, job resources, job burnout, and organizational effectiveness of the private security guards, and the fitness of the model analyzed with CSA was determined by the goodness-of-fit index ($x^2$, df, p, RMR, GFI, CFI, TLI, RMSEA). The level of significance was set at .05, and the following results were obtained. First, even though the effect of job requirements on job burnout was not statistically significant, it had a positive influence overall, and this result can be considered such that the higher the perception of job requirements by the member of the organization, the higher the perception of job burnout. Second, the influence of job resources on job burnout was negative, which can be considered that the higher the perception of job resources, the lower the perception of job burnout. Third, even though the influence of job requirements on organizational effectiveness was statistically nonsignificant, it had a negative influence overall, and this result can be considered that the higher the perception of job requirements, the lower the perception of organizational effectiveness. Fourth, job resources had a positive influence on organizational effectiveness, and it can be considered that the higher the perception of job resources, the higher the perception of organizational effectiveness. Fifth, the results of the analysis between job burnout and organizational effectiveness revealed that, even though the influence of job burnout on organizational effectiveness was statistically nonsignificant, it had partial negative influences on sublevels of organizational effectiveness, and this may suggest that the higher the perception of job burnout by the organization members, the lower the organizational effectiveness. Sixth, the analysis of mediating role in the relationship between job requirements and organizational effectiveness, job burnout was taking partial mediating role between job requirements and organizational effectiveness. These results suggest that reducing job burnout by managing job requirements, organizational effectiveness that leads to job satisfaction, organizational commitment, and turnover intention can be maximized. Seventh, the analysis of mediating role in the relationship among job requirements, job resources, and organizational effectiveness, job burnout was assuming a partial mediating role in the relationships among job requirements, job resources, and organizational effectiveness. These results suggest that organizational effectiveness can be maximized by either lowering job requirements or burnout management through reorganizing job resources.

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