• Spatial Information Research
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• v.11 no.3
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• pp.261-274
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• 2003

The effective probability-based tile pre-fetching algorithm and the collaborative cache replacement algorithm are able to reduce the response time for user's requests by transferring tiles which will be used in advance and determining tiles which should be removed from the restrictive cache space of a client based on the future access probabilities in Web GISs(Geographical Information Systems). The Web GISs have multi-level abstracted data for the quick response time when zoom-in and zoom-out queries are requested. But, the previous pre-fetching algorithm is applied on only two-dimensional pre-fetching space, and doesn't consider expanded pre-fetching space for multi-level abstracted data in Web GISs. In this thesis, a probability-based pre-fetching algorithm for multi-level abstracted in Web GISs was proposed. This algorithm expanded the previous two-dimensional pre-fetching space into three-dimensional one for pre-fetching tiles of the upper levels or lower levels. Moreover, we evaluated the effect of the proposed pre-fetching algorithm by using a simulation method. Through the experimental results, the response time for user requests was improved 1.8%∼21.6% on the average. Consequently, in Web GISs with multi-level abstracted data, the proposed pre-fetching algorithm and the collaborative cache replacement algorithm can reduce the response time for user requests substantially.

• Journal of the Korean Society of Food Culture
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• v.6 no.2
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• pp.175-184
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• 1991

To identify the eating behaviour of customers at a hotel buffet styled restaurant, a survey was conducted. The age range of the respondents was 6 through 70, but consisted mainly people in their twenties, thirties, and forties of the respondents, 65.1% were female. The occupation ranged from student 30.3%, housewife 27.2%, office worker 19.3%, professional 17.3%. 43.9% of respondents visited buffet styled restaurant 1 to 2 times every three or four months. Some respondents had a positive opinions: they had many choices in food selection, they could take and choose as much as they wanted, the appearance and the arrangement of the food was great, etc. But some also had negative attitudes(i.e. unhappy with self service and expensive prices). Of the respondents, 31.1% said they visited the buffet styled restaurant was for family parties and the average number of the party member was $9.3{\pm}4.3$. The average time period of eating was 1 hour $32{\pm}26$ minutes. The average frequency of taking food was $3.7{\pm}1.2$. The average frequency of taking food after satiety was $1.2{\pm}0.8$. The first selection of the buffet service food was soup 23.9% of the respondents and salad 23.9%. Females chose more of the soups and salads the males chose more of the meats and seafoods. The standard of food selection was 70.7% of 'my favorite'. This tells customers' low cognition level of desirable food selection and the order of a meal. 64.0% of the respondents responded overeating, from mild and extreme. We think that information on nutrition education and health problems are necessary. For better service, 82.9% wanted to lower the price by decreasing similar items. Respondent wanted; one, to increase more Korean food items and make a traditional Korean buffet styled restaurant, two, to use more seasonal food and decrease the redundant food items to reduce the price, and three, to have different price rates according to the age or gender of the grown ups.

• Journal of Food Hygiene and Safety
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• v.26 no.3
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• pp.192-197
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• 2011

Rice spent water (RSW) is generated when rice is rinsed before cooking. RSW has been discarded into sewerages due to its low usage in our daily life and become a major domestic wastewater for many years. But RSW can be used as a value-added resource because it contains various beneficial bioactive components. Therefore, fermented rice spent water (FRSW) has been already produced in our previous value-added fermentation process. In this study, proximate compositions and contents of other typical fermentation products were compared between RSW and FRSW. Both RSW and FRSW contain approximately 99.3% moisture and 0.7% total solids. Compared to those of RSW on a dry basis, carbohydrate content of FRSW was decreased by 44.8% and crude protein, lipid, and ash contents of FRSW were increased by 16.4%, 18.8%, and 36.6%, respectively. In addition, starch granules of RSW were intact as those of rice flour were, but those of FRSW were not. RSW did not have lactic acid, but FRSW had 212.13 and 181.25 g/kg D- and L-lactic acid, respectively. Free amino and ammoniacal nitrogen contents of FRSW were 12 and 7 times higher than those of RSW, respectively. Lactic acid, free amino, and ammonical nitrogen contents were considered to be increased in FRSW because carbohydrates could be disintegrated into lactic acids and proteins into free amino or ammoniacal nitrogens during the fermentation process.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.223-231
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• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• Journal of Animal Science and Technology
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• v.44 no.1
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• pp.123-134
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• 2002

An experiment was conducted to establish the most suitable ventilation system for the enclosed nursery pig house in Korea, comparing four different ventilation systems ; i) air enters through perforated ceiling and exhausts through chimney (NA), ii) air enters through perforated ceiling and exhausts through side walls (NB), iii) air enters through perforated ducts and exhausts through side walls (NC) and iv) air enters through perforated ducts and exhausts through chimney(ND). The experiment was carried out during winter and summer separately. The experimental pigs were weaned at fourteen days old in winter (December-February) and at twenty one days old in summer (June-August). The main results of the experiment are as follows : A preliminary experiment showed that in the NC system during summer, air can reach all the pig rooms in the house and the air flow rates of the upper, middle (1.2 m height of the room) and low (at the height of pig stature) parts of the room were measured at 7.0-8.08, over 0.5 and over 0.2 m/s, respectively, which flow rates were much higher(p$<$0.05) than those in other system. At the minimum ventilation efficiency during winter, air flow rates of upper, middle and low parts of the room equipped with the NC system were detected at over 1, less than 0.5 and around 0.07 m/s, respectively. It is concluded that the separated ventilation system air-entering through ducts is the most suitable for the ventilation system of the enclosed nursery pig house and the exhausting system through side walls is more efficient for ventilation than the system through roof. Furthermore, to sustain proper temperature and reduce energy waste as well as heat consumption, a future research should be carried out to develop the environmental control system in relation to developing a heat regulator.

• Journal of KIISE:Information Networking
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• v.35 no.2
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• pp.99-111
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• 2008

In recent years, the needs for WLANs(Wireless Local Area Networks) technology which can access to Internet anywhere have been dramatically increased particularly in SOHO(Small Office Home Office) and Hot Spot. However, unlike wired networks, there are some unique characteristics of wireless networks. These characteristics include the burst packet losses due to unreliable wireless channel. Note that burst packet losses, which occur when the distance between the wireless station and the AP(Access Point) increase or when obstacles move temporarily between the station and AP, are very frequent in 802.11 networks. Conversely, due to burst packet losses, the performance of 802.11 networks are not always as sufficient as the current application require, particularly when they use TCP at the transport layer. The high packet loss rate over wireless links can trigger unnecessary execution of TCP congestion control algorithm, resulting in performance degradation. In order to overcome the limitations of WLANs environment, MAC-layer LDA(Loss Differentiation Algorithm)has been proposed. MAC-layer LDA prevents TCP's timeout by increasing CRD(Consecutive Retry Duration) higher than burst packet loss duration. However, in the wireless channel with high packet loss rate, MAC-layer LDA does not work well because of two reason: (a) If the CRD is lower than burst packet loss duration due to the limited increase of retry limit, end-to-end performance is degraded. (b) energy of mobile device and bandwidth utilization in the wireless link are wasted unnecessarily by Reducing the drainage speed of the network buffer due to the increase of CRD. In this paper, we propose a new retransmission module based on Cross-layer approach, called BLD(Burst Loss Detection) module, to solve the limitation of previous link layer retransmission schemes. BLD module's algorithm is retransmission mechanism at IEEE 802.11 networks and performs retransmission based on the interaction between retransmission mechanisms of the MAC layer and TCP. From the simulation by using ns-2(Network Simulator), we could see more improved TCP throughput and energy efficiency with the proposed scheme than previous mechanisms.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.2
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• pp.2262-2275
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• 1971

Fourteenes rervoirs maintained by the local land improvement associations in the province of Chullabuk-Do and 20 reservoir maintained by thos in the province of Chullanam-Do, were surveyed in connection with a correction between storage capacity and sediment deposit. In addition to this survey, 3,347 of small reservoir, that lie scattered around in the above-mentioned two provinces were investigated by using existing two provinces were investigated by using existing records pertaining to storage capacity in the office of City and country, respectively. According to this investigation the following comclusions are derived. 1. A sediment deposition rate is high, being about $10.63m^3/ha$ of drainage area, and resulting in the average decreasc of storage capaity by 27.5%. This high rate of deposition coule be mainly attributed to the serve denudation of forests due to disorderly cuttings of trees. Easpecially, in small reservoir, an original average design storage depth of 197mm in irrigation water depth is decreased to about 140mm. 2. An average unit storage depth of 325.6mm as the time of initial construction is decreased to 226mm at present. This phenomena causes a greater shortage irrigation water, since it was assumed that original storage quantity was already in short. 3. Generally speaking, seepage rates through dam abutment intakepipe, etc, are high due to insufficient maintenance and management of reservoir. 4. It is recommended that sediment deposit should be dredged when a reservoir is dry in drought. 5. Farmers usually waste excessive irrigation water. 6. Water saving methods should be practiced by applying only necessary water for growing stage of rice. 7. In are as where water defficiency for irrigation is severe, a soil moisture content should be kept at about 70% by applying water once in several days. 8. Tube wells should be provided so as to exploit ground water and subsurface current below stream bed as much as possible. 9. If an intake weir was constructed, a water collection well should be built for the use in drought. 10. Water conservation should be forced by converting devastated forests contained in the drainage area of reservoir to protected forests so as to take priority of yrefor estation, gully control, the prohibition of disorderly cutting of trees, etc. 11. Collective rice nurseries should be adopted, and it should be recommended that irrigation water for rice nurseries is supplied by farmer themselves. 12. Sediment desposit in reservoir should be thoroughly dreged so as to secure a original design storage capacity. 13. The structure of overflow weir should be automatic so as to freely control flood level and not to increase dam height.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.305-316
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• 2011

Recommender system is the system which, by using automated information filtering technology, recommends products or services to the customers who are likely to be interested in. Those systems are widely used in many different Web retailers such as Amazon.com, Netfix.com, and CDNow.com. Various recommender systems have been developed. Among them, Collaborative Filtering (CF) has been known as the most successful and commonly used approach. CF identifies customers whose tastes are similar to those of a given customer, and recommends items those customers have liked in the past. Numerous CF algorithms have been developed to increase the performance of recommender systems. However, the relative performances of CF algorithms are known to be domain and data dependent. It is very time-consuming and expensive to implement and launce a CF recommender system, and also the system unsuited for the given domain provides customers with poor quality recommendations that make them easily annoyed. Therefore, predicting in advance whether the performance of CF recommender system is acceptable or not is practically important and needed. In this study, we propose a decision making guideline which helps decide whether CF is adoptable for a given application with certain transaction data characteristics. Several previous studies reported that sparsity, gray sheep, cold-start, coverage, and serendipity could affect the performance of CF, but the theoretical and empirical justification of such factors is lacking. Recently there are many studies paying attention to Social Network Analysis (SNA) as a method to analyze social relationships among people. SNA is a method to measure and visualize the linkage structure and status focusing on interaction among objects within communication group. CF analyzes the similarity among previous ratings or purchases of each customer, finds the relationships among the customers who have similarities, and then uses the relationships for recommendations. Thus CF can be modeled as a social network in which customers are nodes and purchase relationships between customers are links. Under the assumption that SNA could facilitate an exploration of the topological properties of the network structure that are implicit in transaction data for CF recommendations, we focus on density, clustering coefficient, and centralization which are ones of the most commonly used measures to capture topological properties of the social network structure. While network density, expressed as a proportion of the maximum possible number of links, captures the density of the whole network, the clustering coefficient captures the degree to which the overall network contains localized pockets of dense connectivity. Centralization reflects the extent to which connections are concentrated in a small number of nodes rather than distributed equally among all nodes. We explore how these SNA measures affect the performance of CF performance and how they interact to each other. Our experiments used sales transaction data from H department store, one of the well?known department stores in Korea. Total 396 data set were sampled to construct various types of social networks. The dependant variable measuring process consists of three steps; analysis of customer similarities, construction of a social network, and analysis of social network patterns. We used UCINET 6.0 for SNA. The experiments conducted the 3-way ANOVA which employs three SNA measures as dependant variables, and the recommendation accuracy measured by F1-measure as an independent variable. The experiments report that 1) each of three SNA measures affects the recommendation accuracy, 2) the density's effect to the performance overrides those of clustering coefficient and centralization (i.e., CF adoption is not a good decision if the density is low), and 3) however though the density is low, the performance of CF is comparatively good when the clustering coefficient is low. We expect that these experiment results help firms decide whether CF recommender system is adoptable for their business domain with certain transaction data characteristics.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.3
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• pp.165-181
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• 1976

Fertilizer(N,P,K) demand for crop production in 1980, 1990 and 2000 was estimated according to the two proposed models, one of which is fertilizer use efficiency model expressed in $Fn=(Y/E){\cdot}(1-Cs)Eu$, where Fn:fertilizer demand, Y:Crop production estimated, E:nutrient efficiency, Cs:fraction of natural resource nutrient in plant, Eu:fertilizer use efficiency and the other fertilization efficiency model expressed in Fn=Y(1-Cys)/Fe, where Cys:fraction of yield without fertilizer, Fe:fertilization efficiency. Total crop uptake of nutrient and its noncycling portion were estimated as criteria for fertilizer demand and nutrient maintenance. Total crop uptake of N,P,K was 600,000 M/T in 1965 700,000 M/T in 1974 and estimated to 880,000 M/T in 1980, 1,170,000 M/T in 1990 and 1,410,000 M/T in 2000. Fertilizer demand appeares to be about 90% of total crop uptake according to fertilizer use efficiency model and about 87% according to fertilization efficiency model. The noncycling nutrient was about 29% of total crop uptake. Fertilizer demand was almost same to the uptake amount in nitrogen, 1.5 times of uptake in phosphorus and half of uptake in potassium. Varietal development, improvement of soil fertility and cultivation method and development of fertilizer forms appears to decrease fertilizer demand by increasing efficiency term in two models while environmental stress such as low temperature appears to give reverse effect resulting in higher fertilizer demand. Fertilizer consumption in 1974 seemed to be unreasonably high especially in nitrogen and phosphorus and thus the effective use of fertilizer appeared as an urgent problem considering that large fields are still remained in lower fertility.

• Management & Information Systems Review
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• v.35 no.3
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• pp.57-79
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• 2016

It is required to derive various conclusions by identifying the type of power and the relationship between SCMs and presenting practical implications. Thus, we can identify the differential effects of each type of power on SCM performance. We can contribute to develop the practical implications at more sophisticated multi-dimension by comparing results of this study with various SCM theories. Through previous studies, the source of power is largely divided into binding power and non-binding power. Binding power is classified into behavior coercion, binding reward and relationship legitimacy. Non-binding power is classified into work expertise, information superiority and value compliance. Enterprises should fully understand and recognize partners within supply chains including understanding of the source of power, imbalance and results. Thus, we look into types of power and effects on trust and commitment, and identify a causal relationship leading to collaboration and SCM performance. Specific research results are as follows. First, the binding power did not give a significant effect to the trust. However, the binding power gave a positively(+) significant effect to the commitment. Second, non-binding power showed a significant effect on both trust and commitment. As a result of analysis on total effects, it was shown that non-binding power gave indirect effects to collaboration and SCM performance. Third, it was shown that both trust and commitment significantly affected collaboration. From the perspectives of social exchange theory and trading cost theory among inter-organizational relationship theory, it may lead to SCM performance of trust, commitment and collaboration. Moreover, it was found that association of each attribute of power led to the significant result. Fourth, it was shown that trust and collaboration significantly affected SCM performance. However, commitment did not directly affect SCM performance, but it indirectly significantly affected SCM performance through collaboration. Proper use of this power can firmly build partnerships between members of the supply chain and induce the improvement on supply chain performance and satisfaction of members.