• Journal of Intelligence and Information Systems
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• v.18 no.4
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• pp.43-57
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• 2012

To enhance the competitive advantage in a constantly changing business environment, an enterprise management must make the right decision in many business activities based on both internal and external information. Thus, providing accurate information plays a prominent role in management's decision making. Intuitively, historical data can provide a feasible estimate through the forecasting models. Therefore, if the service department can estimate the service quantity for the next period, the service department can then effectively control the inventory of service related resources such as human, parts, and other facilities. In addition, the production department can make load map for improving its product quality. Therefore, obtaining an accurate service forecast most likely appears to be critical to manufacturing companies. Numerous investigations addressing this problem have generally employed statistical methods, such as regression or autoregressive and moving average simulation. However, these methods are only efficient for data with are seasonal or cyclical. If the data are influenced by the special characteristics of product, they are not feasible. In our research, we propose a forecasting framework that predicts service demand of manufacturing organization by combining Case-based reasoning (CBR) and leveraging an unsupervised artificial neural network based clustering analysis (i.e., Self-Organizing Maps; SOM). We believe that this is one of the first attempts at applying unsupervised artificial neural network-based machine-learning techniques in the service forecasting domain. Our proposed approach has several appealing features : (1) We applied CBR and SOM in a new forecasting domain such as service demand forecasting. (2) We proposed our combined approach between CBR and SOM in order to overcome limitations of traditional statistical forecasting methods and We have developed a service forecasting tool based on the proposed approach using an unsupervised artificial neural network and Case-based reasoning. In this research, we conducted an empirical study on a real digital TV manufacturer (i.e., Company A). In addition, we have empirically evaluated the proposed approach and tool using real sales and service related data from digital TV manufacturer. In our empirical experiments, we intend to explore the performance of our proposed service forecasting framework when compared to the performances predicted by other two service forecasting methods; one is traditional CBR based forecasting model and the other is the existing service forecasting model used by Company A. We ran each service forecasting 144 times; each time, input data were randomly sampled for each service forecasting framework. To evaluate accuracy of forecasting results, we used Mean Absolute Percentage Error (MAPE) as primary performance measure in our experiments. We conducted one-way ANOVA test with the 144 measurements of MAPE for three different service forecasting approaches. For example, the F-ratio of MAPE for three different service forecasting approaches is 67.25 and the p-value is 0.000. This means that the difference between the MAPE of the three different service forecasting approaches is significant at the level of 0.000. Since there is a significant difference among the different service forecasting approaches, we conducted Tukey's HSD post hoc test to determine exactly which means of MAPE are significantly different from which other ones. In terms of MAPE, Tukey's HSD post hoc test grouped the three different service forecasting approaches into three different subsets in the following order: our proposed approach > traditional CBR-based service forecasting approach > the existing forecasting approach used by Company A. Consequently, our empirical experiments show that our proposed approach outperformed the traditional CBR based forecasting model and the existing service forecasting model used by Company A. The rest of this paper is organized as follows. Section 2 provides some research background information such as summary of CBR and SOM. Section 3 presents a hybrid service forecasting framework based on Case-based Reasoning and Self-Organizing Maps, while the empirical evaluation results are summarized in Section 4. Conclusion and future research directions are finally discussed in Section 5.

• Korea journal of population studies
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• v.35 no.1
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• pp.101-130
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• 2012

This study examines mortality change in North Korea and its association with state production and welfare systems. Two main subjects are analyzed. The first theme is to examine the reliability of mortality related data released by North Korea government authorities. Examining inner consistencies among mortality related statistics and comparing with mortality trends in other socialist societies, the study finds that mortality rate was under estimated. Under-estimation of mortality by North Korean authorities is regarded to result not only from political purpose which aims to propagate the regime's superiority but also from enumeration errors of vital statistics based on the residence registration. The second theme is to estimate the change in mortality of North Korean people since the establishment of DPRK, correcting errors of mortality data. Mortality of North Korean people is estimated to have improved largely by the early 1970s, to have been sluggish hereafter, and finally to have increased during the economic hardship period between 1993 and 2008. While large people died during the food crisis in the late 1990s, however the population loss caused by mortality increase was not so great as the proposition of the huge starvation was expected. It is partly because population turbulence occurred not just by mortality increase, rather it has progressed in the joint effects of fertility decline and exodus of North Korean people for food. It is also due to North Korean people's voluntary activities of informal economy. It is also worth noting the high mortality rate of North Korean men. The high mortality of North Korean men is likely due to men's mobilization for long time in army and labor with high risk of accident and their life styles.

• Clean Technology
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• v.19 no.3
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• pp.264-271
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• 2013

In this study, we optimized the removal condition of contaminants attached on the scrap surface to recycle the scrap generated from the Zr alloy tube manufacturing process back to the nuclear grade. The main contaminant is remnant of watersoluble cooling lubricant that is used in the pilgering manufacture during the tube production, and it is assumed to be compressed and carbonized on the surface of tube. Zirlo alloy tube of ${\phi}9.50mm$, which has high occurrence frequency of scrap, was selected as the object to be cleaned, and cleaning abilities of reagents were evaluated by measuring the characteristics of contaminants remained and by analyzing the surface of the tube after cleaning process. For evaluation of each cleaning agent, we selected two types of sodium hydroxide series and three types of potassium hydroxide series. Furthermore, to confirm dependence on tempe-rature and ultrasonic intensities, cleaning at the room temperature, $40^{\circ}C$, and $60^{\circ}C$ was conducted, and results showed that higher the cleaning temperature and higher the ultrasonic intensity, better the cleaning effect. As a result of the bare-eye inspection, while the use of sodium hydroxide provided satisfactory condition on the tube surface, the use of potassium hydroxide series provided satisfactory condition on the tube surface only when the ultrasonic intensity was over 120 W. In the cleaning effect analysis using the gravimetric method, cleaning efficiency of sodium hydroxide series was as high as 97.6% ($60^{\circ}C$, 120 W), but since the tube surface condition was poor after the use of potassium hydroxide, the gravimetric method was not appropriate. In the analytical result of surface contaminants on the tube surface, C, O, Ca, and Zr were detected, and mainly C and O dominated the proportion of contaminants. It was also found that the degree of cleaning on the tube affected the componential ratio of C and O; if the degree of cleaning is high, or if cleaning is well-conducted, the proportion of C is decreased, and the proportion of O is increased. Based on these results, optimal cleaning for application in the industry can be expected by categorizing cleaning process into three steps of Alkali cleaning, Rinsing, and Drying and by adjusting cleaning parameters in each step.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.1 s.6
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• pp.15-29
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• 2005

Truck Shipment Safety Information, which is a part of the development of NERIS is divided into Optimal Route Guidance System and Emergency Response System. This research is for establishing an advance warning system, which aims for preventing damages(fire, explosion, gas-escape etc.) and detecting incidents that are able to happen during transporting hazardous materials in advance through monitoring the position of moving vehicles and the state of hazardous materials in real-time. This research is peformed to confirm the practical possibility of application of the advance warning system that monitors whether the hazardous materials transport vehicles move the allowed routes, finds the time and the location of incidents of the vehicles promptly and develops the emergency system that is able to respond to the incidents as well by using the technologies of CPS, CDMA and CIS with testing the ability of performance. As the results of the test, communication accuracies are 99$\%$ in freeway, 96$\%$ in arterial, 97$\%$ in hilly sections, 99$\%$ in normal sections, 96$\%$ in local sections, 99$\%$ in urban sections and 98$\%$ in tunnels. According to those results, the system has been recorded a high success rate of communication that enough to apply to the real site. However, the weak point appeared through the testing is that the system has a limitation of communication that is caused in the rural areas and certain areas where are fewer antennas that make communication possible between on-board unit and management server. Consequently, for the practical use of this system, it is essential to develop the exclusive en-board unit for the vehicles and find the method that supplements the receiving limitation of the GPS coordinates inside tunnels. Additionally, this system can be used to regulate illegal acts automatically such as illegal negligence of hazardous materials. And the system can be applied to the study about an application scheme as a guideline for transporting hazardous materials because there is no certain management system and act of toxic substances in Korea.

• The Journal of the Korean bone and joint tumor society
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• v.13 no.1
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• pp.60-66
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• 2007

Purpose: The purpose of this study was to evaluate the functional outcomes of periacetabular malignant bone tumors treated by internal pelvectomy without reconstruction. Materials and methods: Between January 1996 and December 2005, eight patients with primary malignant or metastatic periacetabular bone tumors were treated by internal pelvectomy without reconstruction. There were 6 men and 2 women. Mean age was 42 years old. There were 3 osteosarcomas, 3 chondrosarcomas and 2 metastatic carcinomas. The type of pelvic resections were 6 type I+II+III, 1 type I+II and 1 type II+II resection. The functional outcomes were evaluated with ISOLS revised criteria. The follow up period ranged from 6 to 84 months. Results: At last follow up, 5 patients showed CDF, 2 patients, AWD and the remained 1, DOD. The mean functional score for pain, functional activity, emotional acceptance, use of external support, walking ability and gait were 4.9, 2.9, 2.9, 1.5, 2.3 and 2.5 respectively. The total functional score ranged from 37% to 70%(average: 56%). There were three temporary nerve palsies. Conclusion: The internal pelvectomy without reconstruction for selective difficult periacetabular malignant tumors could be a viable option with fewer complications and fair functional outcomes.

• Korean Journal of Poultry Science
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• v.39 no.4
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• pp.291-295
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• 2012

The use of methylacetamide (MA) as a cryoprotective agent for freezing Korean Native Black rooster Ogye semen was examined with artificial insemination. The diluted Ogye semen with HS-1 was subjected for 2 step dilution method of cryopreservation in which the final concentration of MA was adjusted to 7.5%. The sperm viability after thawing was reduced from $95.17{\pm}0.93%$ to $55.93{\pm}1.38%$ which was confirmed by live-death analysis based on Fluorescence-Activated Cell Sorting (FACS). The rates of fertilized eggs with fresh or frozen-thawed semen were reduced from $94.98{\pm}3.93%$ to $66.36{\pm}8.43%$ at day 7 with significant difference. However, the hatching rates of experiments at day 21 did not shown difference between $92.64{\pm}2.33%$ and $90.45{\pm}8.05%$ (P<0.05). With these results, the utilization of MA for freezing of Ogye spermatozoa could affect on viability of frozen-thawed semen but not on the fertility of lain eggs and hatchability of fertilized eggs and also provide possible tools of freezing for poultry genetic resource conservation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.1-7
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• 2005

Tidal flats have been regarded to carry out transformation and removal of land-derived organic matter, and this purifying capability of organic matter by tidal flats is one of very important reasons for their conservation. However, integral biogeochemical studies on production and decomposition of organic matter by benthic microbes in tidal flats have been absent in Korea, although the information is indispensable to quantification of the purifying capability. Our major goals in this multidisciplinary research were to understand major biogeochemical processes and rates mediated by diverse groups of microbes dominating material cycles in the tidal flats, and to assess the contribution of benthic microbes to removal of organic matter and nutrients in the tidal flats. Our study sites were Ganghwa and Incheon north-port tidal flats that had been regarded as naturally well reserved and organically polluted, respectively. Our research group measured over 3 years primary production, biomass and community structure of primary producers, abundance and production of bacteria, enzyme activities, distribution of protozoa and protozoan grazing rates, rates of denitrification and sulfate reduction, early sediment diagenesis, primary production and respiration based on oxygen microelectrode. We analyzed major features of each biogeochemical process and their interactions. The results are compiled in the following articles in this special issue: An (2005), Hwang and Cho (2005), Mok et at. (2005), Na and Lee (2005), Yang et at. (2005), and Yoo and Choi (2005).

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.366-373
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• 2000

Toxin production and low digestibility of cyanobacteria are known to cause low exploitability of cyanobacteria by zooplankton. In this study, we compared relative tolerance and compatibility of zooplankton taxa in eight eutrophic lakes, exposed to frequent cyanobacterial blooms, uring the summer season of 1999. Microcystis, Anabaena, Oscillatoria and Phormidium were common cyanobacteria in all lakes. with relatively lower $NO_3-N$ concentration (<0.2 mgN/l) and TN/TP ratio (<20), compared with other lakes where colonial cyanobacteria dominated. Rotifers were dominant zooplankton in most lakes, and among them, Keratella, Polyarthra and Hexathra were common. The laboratory feeding experiment showed that relative copepods that greatly decreased (90%) after 4 day when cyanobacteria were used as the food source of zooplankton, while rotifers gradually increased with the change of dominant taxa from Keratella through Pompholyx to Monostyla. These results suggest that rotifers may be capable of coexisting with cyanobacteria by exploiting them for the food source.

• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.113-130
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• 2002

In this paper, we developed DNL(Dynamic Network Loading) model based on Moving cell theory to analyze the dynamic characteristics of traffic flow in congested network. In this paper vehicles entered into link at same interval would construct one cell, and the cells moved according to Cell following rule. In the past researches relating to DNL model a continuous single link is separated into two sections such as running section and queuing section to describe physical queue so that various dynamic states generated in real link are only simplified by running and queuing state. However, the approach has some difficulties in simulating various dynamic flow characteristics. To overcome these problems, we present Moving cell theory which is developed by combining Car following theory and Lagrangian method mainly using for the analysis of air pollutants dispersion. In Moving cell theory platoons are represented by cells and each cell is processed by Cell following theory. This type of simulation model is firstly presented by Cremer et al(1999). However they did not develop merging and diverging model because their model was applied to basic freeway section. Moreover they set the number of vehicles which can be included in one cell in one interval so this formulation cant apply to signalized intersection in urban network. To solve these difficulties we develop new approach using Moving cell theory and simulate traffic flow dynamics continuously by movement and state transition of the cells. The developed model are played on simple network including merging and diverging section and it shows improved abilities to describe flow dynamics comparing past DNL models.

• KSBB Journal
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• v.21 no.4
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• pp.248-254
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• 2006

Animal cell culture industry has a large market and an exponential growth rate among biological industry field. Chines hamster ovary(CHO) cells are the most widely used cell lines for recombinant protein production. They can avoid infection from polio, herpes, hepatitis B, HIV, measles, adenovirus and etc. Moreover it is easy to transfection recombinant genes and possible to suspension culture. Serum free media is one of the most important factor of protein production. Because serum has problems. Serum is not defined the contents until now, it has a number of proteins, lipids, carbohydrates and unknown molecules that cause of risk involve in infection and high cost of product purification. CHO cell line cultured using serum free media were the basis of a very successful method to produce(glyco-)protein in mammalian cells, which are then used as pharmaceutical products. Also, the low protein content of the developed medium facilitates downstream processing and product purification. But non-adapted CHO cells have a limit of proliferation cultured using serum free media and it takes very long time to adapt non-adapted cells to serum free media. There are a number of causes of a limit of proliferation using serum free media. Absence of growth factors and growth stimulating molecules is a major factor of the reasons. It makes growth signals and moves cell cycle. And increase of cellular stress is another reason. It induces increase of intraceullar ROS concentration. The purpose of this study is about improvement of proliferation capacity of non-adapted CHO cells cultured using serum free media without adaptation process.