• 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.

• The Journal of the Korean life insurance medical association
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• v.4 no.1
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• pp.44-76
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• 1987

Present study was undertaken to establish the modified Broca's indices to estimate standard body weight by using a total of 5,496 insured persons who were medically examined at the Honam Medical Room of Dong Bang Life Insurance Company Ltd. from January, 1983 to January, 1986. The results were as follows: 1. The linear regression equations of body weight to $height^3$ to estimate standard body weight were as follows: In male, for $18{\sim}19$ age group $y=7.272{\times}10^{-6}{\times}x^3+23.560$ for $20{\sim}29$ age group $y=8.187{\times}10^{-6}{\times}x^3+22.031$ for $30{\sim}39$ age group $y=8.627{\times}10^{-6}{\times}x^3+23.169$ for $40{\sim}49$ age group $y=9.561{\times}10^{-6}{\times}x^3+20.994$ for $50{\sim}59$ age group $y=8.604{\times}10^{-6}{\times}x^3+23.081$ and for all ages group $y=7.778{\times}10^{-6}{\times}x^3+25.929$ In female, for $18{\sim}19$ age group $y=8.252{\times}10^{-6}{\times}x^3+18.920$ for $20{\sim}29$ age group $y=7.715{\times}10^{-6}{\times}x^3+22.409$ for $30{\sim}39$ age group $y=8.808{\times}10^{-6}{\times}x^3+21.440$ for $40{\sim}49$ age group $y=9.691{\times}10^{-6}{\times}x^3+21.940$ for $50{\sim}59$ age group $y=12.550{\times}10^{-6}{\times}x^3+11.031$ and for all ages group $y=7.300{\times}10^{-6}{\times}x^3+26.601$ In both sexes, for all ages group $y=8.342{\times}10^{-6}{\times}x^3+22.998$ 2. The modified Broca's index is expressed by formula $\{height(cm)-100\}{\times}K(kg)$. K is obtained from the following formula standard weight to average height estimated $\frac{by\;means\;of\;linear\;regression\;equation(kg)}{\{Average\;height(cm)-100\}{\times}K(kg)}$=1 Author's modified Broca's indices are as follows: In male, for $18{\sim}19$ age group $\{height(cm)-100\}{\times}0.85(kg)$ for $20{\sim}29$ age group $\{height(cm)-100\}{\times}0.90(kg)$ for $30{\sim}39$ age group $\{height(cm)-100\}{\times}0.95(kg)$ for $40{\sim}49$ age group $\{height(cm)-100\}{\times}1.00(kg)$ for $50{\sim}59$ age group $\{height(cm)-100\}{\times}0.95(kg)$ and for all ages group $\{height(cm)-100\}{\times}0.95(kg)$ In female, for $18{\sim}19$ age group $\{height(cm)-100\}{\times}0.90(kg)$ for $20{\sim}29$ age group $\{height(cm)-100\}{\times}0.90(kg)$ for $30{\sim}39$ age group $\{height(cm)-100\}{\times}1.00(kg)$ for $40{\sim}49$ age group $\{height(cm)-100\}{\times}1.05(kg)$ for $50{\sim}59$ age group $\{height(cm)-100\}{\times}1.05(kg)$ and for all ages group $\{height(cm)-100\}{\times}1.00(kg)$ In both sexes, for all age group $\{height(cm)-100\}{\times}0.95(kg)$ 3. Several types of modified Broca's index recommended by author are as follows: I. In male, for $18{\sim}29$ age group $\{height(cm)-100\}{\times}0.90(kg)$ and for $30{\sim}59$ age group $\{height(cm)-100\}{\times}0.95(kg)$ In female, for $18{\sim}29$ age group $\{height(cm)-100\}{\times}0.90(kg)$ and for $30{\sim}39$ age group $\{height(cm)-100\}{\times}1.00(kg)$ II. In male, for all ages group $\{height(cm)-100\}{\times}0.95(kg)$ In female, for all ages group $\{height(cm)-100\}{\times}1.00(kg)$ III. In both sexes, for all ages group $\{height(cm)-100\}{\times}0.95(kg)$ Note: The first type of modified Broca's index is the most precise one in estimating standard body weight among several types established by author. 4. Error of estimated standard body weight appearing by applying modified Broca's indices is generally greater in short build persons than in tall build persons and is more dominant especially in female group.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.57-64
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• 1999

Purpose : Paclitaxel is a chemotherapeutic agent with a potent microtubule stabilizing activity that arrests mitosis at G2-M phase of cell cycle which is the most radiosensitive period. Therefore paclitaxel is considered as a cell cycle-specific radiosensitizer. This study investigates the effect of paclitaxel on the radiation response of the normal large bowel mucosa of the rat. Materials and Methods: The rats were divided into the three groups i.e., single intraperitoneal infusion of paclitaxel (10 mg/kg), a single fraction of irradiation (8 Gy, x-ray) to the whole abdomen, and a combination of irradiation (8 Gy, x-ray) given 24 hours after paclitaxel infusion. The histological changes as well as kinetics of mitotic arrest and apoptosis were evaluated on the large bowel mucosa at 6 hours, 1 day, 3 days and 5 days after treatment with paclitaxel alone, radiation alone and combination of paclitaxel and radiation. Results : The incidence of the mitotic arrest was not increased by paclitaxel infusion. The apoptosis appeared in 24 hours after paclitaxel infusion, and the histopathologic changes such as vesiculation, atypia and reduction of the goblet cell of the mucosa of the large bowel were demonstrated during the period from 6 hours to 3 days after, and returned to normal in 5 days after paclitaxel infusion. In irradiated group, the apoptosis was increased in 6 and 24 hours after irradiation, and the histopathologic changes of the mucosa were appeared in 24 hours and markedly increased in 3 days and returned to normal in 5 days. In combined group of irradiation and paclitaxel infusion, the apoptosis was appeared in 3 days and the histopathologic changes appeared during the period from 6 hours to 3 days after infusion. On the basis of the incidence of apoptosis and the degree of the histopathologic changes of the large bowel mucosa, there seemed to be additive effect by paclitaxel on radiation rather than sensitizing effect. Conclusions: The histopathological changes of large bowel mucosa in combined group compared to radiation alone group suggested an additive effect of paclitaxel on radiation response in the large bowel of rat.

• Korean Journal of Microbiology
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• v.39 no.2
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• pp.95-101
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• 2003

The total bacterial numbers, Eubacterial community structures and environmental factors which affect bacterial community were estimated monthly using DAPI and fluorescent in situ hybridization monthly, from June to November 2000 to evaluate the correlation between the bacterial community and environmental factors in eutrophic agricultural Masan reservoir in Asan. Average water temperatures varied from 12.3 to $27.5^{\circ}C$, pH 7.5 to 9.0, DO 7. I~12.8 mg/L, COD 6.4~13.0 mg/L, chlorophyll a 30.5~99.0 mg/㎥, SS 7.S~25.7 mg/L, TN 1.748~3.543 mg/L., and TP 0.104~0.581 mg/L, respectively. Total bacterial numbers showed high ranges from 0.4 to 9.6$\times$ $10^{6}$ cells/ml, and these indicated the mesotrophic or eutrophic state. The ratio of Eubacteria to total bacteria was 67.6-88.0%, which was higher than that in other reservoir. The relationships of total bacteria and Eubacteria community were more significant with organic nitrogen (Org-N), and organic phosphorus (Org-P) than with water temperature. Proteobacteria groups showed strongly significant relationships with Org-P and Org-N and significant relationships with water temperature, conductivity, COD, and inorganic nitrogen. C-F group was the most significant with Org-N, and HGC group with water temperature. However, relationships of Chl-a, pH, DO and SS showed no significance with any bacterial community. These results were different from other studies, because of the specific characteristics of Masan reservoir such as old, shallow and eutrophic states. The seasonal variation of bacterial community in Masan reservoir does not seem to depend on phytoplankton dynamics but on storm event and organic materials from watershed and the sediment of reservoir.

• Journal of Oral Medicine and Pain
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• v.37 no.4
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• pp.233-242
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• 2012

The purposes of this study were to compare psychological profiles, to investigate the differences in the clinical characteristics, and to compare treatment outcomes between myogenous pain and arthrogenous pain subgroups of temporomandibular disorder (TMD) based on Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD). Two hundred and fifty two patients diagnosed as TMD were divided into three groups based on the RDC/TMD axis I diagnostic guidelines; myogenous pain group, arthrogenous pain group, and mixed pain (both myogenous pain and arthrogenous pain) group. RDC/TMD history questionnaire was administered to each patient and depression, somatization, jaw disability, pain intensity, disability days, and graded chronic pain scale were analyzed. Bruxism, clenching, insomnia, headache, and unilateral chewing were assessed in a standardized TMD dysfunction questionnaire and the duration of onset, chronicity of pain, treatment period, the effectiveness of the treatment, and improvement of symptoms also analyzed. Myogenous pain group had higher depression (p=0.002), and somatization scales (p<0.001) than the arthrogenous pain group. Mixed pain group showed higher pain intensity (p=0.008), disability days (p<0.001), graded chronic pain scale (p=0.005), somatization (p<0.001), and depression scores (p=0.002) than the arthrogenous pain group. Jaw disability did not show any significant differences among the three groups (p=0.058). Arthrogenous pain group reported more limitation of mouth opening than myogenous pain group (p=0.007). Duration of onset showed that the arthrogenous pain group had lowest prevalence of chronicity among three groups (p=0.002). Mixed pain group patients showed lowest symptom improvements among three groups (p=0.007). Multiple linear regression analysis results showed that the treatment effectiveness was significantly associated with somatization score (${\beta}$=-0.251, p=0.03).

• Journal of Periodontal and Implant Science
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• v.31 no.1
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• pp.1-23
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• 2001

Chitosan is biodegradable natural polymer that has been demonstrated its ability to improve wound healing, and calcium metaphosphate(CMP) is a unique class of phosphate minerals having a polymeric structure. In this study, chitosan/CMP and platelet derived growth factor(PDGF-BB) loaded chitosan/CMP sponges were developed, and the effect of the sponges on bone regeneration and their possibility as scaffolds for bone formation by three-dimensional osteoblast culture were examined. PDGF-BB loaded chitosan/CMP sponges were prepared by freeze-drying of a mixture of chitosan solution and CMP powder, and soaking in a PDGF-BB solution. Fabricated sponge retained its 3-dimensional porous structure with $100-200\;{\mu}m$ pores. The release kinetics of PDGF-BB loaded onto the sponge were measured in vitro with $^{125}I-labeled$ PDGF-BB. In order to examine their possibility as scaffolds for bone formation, fetal rat calvarial osteoblastic cells were isolated, cultured, and seeded into the sponges. The cell-sponge constructs were cultured for 28 days. Cell proliferation, alkaline phosphatase activity were measured at 1, 7, 14 and 28 days, and histologic examination was performed. In order to examine the effect on the healing of bone defect, the sponges were implanted into rat calvarial defects. Rats were sacrificed 2 and 4 weeks after implantation and histologic and histomorphometrical examination were performed. An effective therapeutic concentration of PDGF-BB following a high initial burst release was maintained throughout the examination period. PDGF-BB loaded chitosan/CMP sponges supported the proliferation of seeded osteoblastic cells as well as their differentiation as indicated by high alkaline phosphatase activities. Histologic findings indicated that seeded osteoblastic cells well attached to sponge matrices and proliferated in a multi-layer fashion. In the experiments of implantation in rat calvarial defects, histologic and histomorphometric examination revealed that chitosan/CMP sponge promoted osseous healing as compared to controls. PDGF-BB loaded chitosan/CMP sponge further echanced bone regeneration. These results suggested that PDGF-BB loaded chitosan/CMP sponge was a feasable scaffolding material to grow osteoblast in a three-dimentional structure for transplantation into a site for bone regeneration.

• Korean Journal of Agricultural Science
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• v.29 no.2
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• pp.43-52
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• 2002

This study was performed to provide the basic data for preservation and improvement of genetic resources according to finding genetic construction obtained from analysis of genetic characteristics of $\beta$-casein gene in Korean Native goat and Saanen using the PCR-RFLP. This study confirmed the amplified products of 481bp fragments obtained from the amplification of $\beta$-casein loci by PCR. The $\beta$-casein AB genotype showed 481, 284 and 197bp, and $\beta$-casein BB genotype showed 284 and 197bp fragments in Korean Native goat and Saanen. The frequencies of $\beta$-casein genotype in Korean Native goat were 6.25 and 93.75% for AA and AB and the frequencies of $\beta$-casein genotype in Saanen were 57.14 and 42.86% for AA and AB types. The frequencies of $\beta$-casein A and B alleles were 0.031 and 0.969 in Korean Native goat and the frequencies of $\beta$-casein A and B alleles are 0.286 and 0.714 in Saanen, respectively. The nucleotide sequence of $\beta$-casein gene of Korean Native goat was 97.71% higher homology with 11 nucleotide sequences difference of that of goat reported in GeneBank (M90556). Therefore, this study of molecular genetic characteristics by the analysis of genetic polymorphism and sequencing for $\beta$-casein gene should be used as basic and applying data for preservation and improvement of genetic resources in Korean Native goat breeding.

• Management & Information Systems Review
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• v.28 no.2
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• pp.41-67
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• 2009

Organizational interpersonal supervisory trust, organizational justice(distributive and procedural justice) and job satisfaction have been lately more spotlighted as generally concluded by many previous studies. The purpose of this study is to find out possible effects of these three factors upon organizational commitment. The results of this study can be outlined as follows: First, it was found that organizational trust, a preceding variable, had significant positive effects on distributive and procedural justice, as well as on organizational commitment as a dependent variable. Second, it was found that two independent variables, i.e. distributive and procedural justice had significant positive effects upon job satisfaction, and procedural justice had significant positive effects on organizational commitment as a dependent variable, but distributive fairness had no significant effects on organizational commitment. Third, it was found that job satisfaction, an independent variable, had significant positive effects on organizational commitment. Fourth, it was found that organizational trust had significant positive secondhand associations with organizational commitment by way of distributive and procedural justice and job satisfaction, and also had overall significant positive effects on organizational commitment. Thus, it is concluded that the higher organizational trust is an index of higher organizational commitment. Fifth, it was found that distributive justice had just significant secondhand effects on organizational commitment by way of job satisfaction, but it had no significant effects overall upon organizational commitment, since such secondhand effects were considerably set off due to negative firsthand effects of distributive justice upon organizational commitment. But procedural justice and job satisfaction had significant firsthand and overall effects on organizational commitment, so it is concluded that the higher procedural justice and the higher job satisfaction are good indices of the higher organizational commitment. Hence, it is concluded that organizational supervisory trust has positive effects on distributive and procedural justice and organizational commitment; distributive justice has positive effects on job satisfaction; procedural justice has positive effects on job satisfaction and organizational commitment; and job satisfaction has positive effects on organizational commitment, so these empirical findings hereof are consistent with general results of previous studies.

• Journal of The Korean Association For Science Education
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• v.25 no.4
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• pp.441-449
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• 2005

The purpose of this study was to examine the degree of cognitive conflict by learner personality and the method of presenting anomalous data to induce cognitive conflict. The participants of this study were 461 high school students. To arose cognitive conflict, an actual demonstration was done for half of the participants and a logical article for the rest. MBTI (Myers-Briggs Type Indicator) was used to find the learner personality types, and CCLT (Cognitive Conflict Level Test) was used to measure the degree of cognitive conflict aroused when anomalous data was confronted. The results of this study indicated that learner personality types influence the degree of cognitive conflict. First, participants were divided into two personality types via preferences on each of the four preference indices; extraversion (E) or introversion (I), sensing (S) or intuition (N), thinking (T) or feeling (F), judgment (J) or perception (P). The cognitive conflict scores of the thinking types were significantly higher than those of the feeling types. Participants were also divided four personality types according to personality functional types: ST, SF, NT and NF. SF type showed a significantly lower cognitive conflict score than any of the other types. According to the type of learner personality, cognitive conflict was influenced differently by the method of presenting anomalous data. For example, the judgment types had a higher cognitive conflict score by logical argument, and the perception types showed a higher score by demonstration. In conclusion, learner cognitive conflicts were influenced by personality types and the methods of presenting anomalous data.

• Journal of The Korean Association For Science Education
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• v.34 no.7
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• pp.677-691
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• 2014

Understanding of the nature of science (NOS) has been a consistent topic as one of the most important goals in science education for the past several decades. Even though there is a variety of research related with the NOS conducted in science education, few researches has been conducted for the conception of scientists regards to the nature of science (Bayir et al., 2014; Taylor et al., 2008; Wong & Hudson, 2008). Recently, researchers in science education turned their attention to identifying views of scientists about the nature of science since they recognized the importance of participation of scientists in science education (Southerland et al., 2003; Taylor et al., 2008). This study was conducted to examine the Korean scientists' views of the nature of science. Through the use of semi-structured questionnaire and in-depth interview the views of 35 scientists who belong to the Korean-American Scientists and Engineers Association (KSEA) regards to the nature of science were explored. Findings show that while the scientists have more informed views with respect to the tentativeness of scientific knowledge, cultural and social influence embedded in science, the limitation of science, and the collaboration of science with others, the scientists have more na${\ddot{i}}$ve views about the distinction between laws and theories, the existence of a universal scientific method, and the importance of imagination and creativity. As such, it can be assumed that the scientists cannot conceptualize their notion in a philosophical sense even though they are engaged in scientific work in reality (Bayir et al., 2014).