• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.19-38
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• 2017

Collaborative filtering (CF) algorithm has been popularly used for implementing recommender systems. Until now, there have been many prior studies to improve the accuracy of CF. Among them, some recent studies adopt 'hybrid recommendation approach', which enhances the performance of conventional CF by using additional information. In this research, we propose a new hybrid recommender system which fuses CF and the results from the social network analysis on trust and distrust relationship networks among users to enhance prediction accuracy. The proposed algorithm of our study is based on memory-based CF. But, when calculating the similarity between users in CF, our proposed algorithm considers not only the correlation of the users' numeric rating patterns, but also the users' in-degree centrality values derived from trust and distrust relationship networks. In specific, it is designed to amplify the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the trust relationship network. Also, it attenuates the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the distrust relationship network. Our proposed algorithm considers four (4) types of user relationships - direct trust, indirect trust, direct distrust, and indirect distrust - in total. And, it uses four adjusting coefficients, which adjusts the level of amplification / attenuation for in-degree centrality values derived from direct / indirect trust and distrust relationship networks. To determine optimal adjusting coefficients, genetic algorithms (GA) has been adopted. Under this background, we named our proposed algorithm as SNACF-GA (Social Network Analysis - based CF using GA). To validate the performance of the SNACF-GA, we used a real-world data set which is called 'Extended Epinions dataset' provided by 'trustlet.org'. It is the data set contains user responses (rating scores and reviews) after purchasing specific items (e.g. car, movie, music, book) as well as trust / distrust relationship information indicating whom to trust or distrust between users. The experimental system was basically developed using Microsoft Visual Basic for Applications (VBA), but we also used UCINET 6 for calculating the in-degree centrality of trust / distrust relationship networks. In addition, we used Palisade Software's Evolver, which is a commercial software implements genetic algorithm. To examine the effectiveness of our proposed system more precisely, we adopted two comparison models. The first comparison model is conventional CF. It only uses users' explicit numeric ratings when calculating the similarities between users. That is, it does not consider trust / distrust relationship between users at all. The second comparison model is SNACF (Social Network Analysis - based CF). SNACF differs from the proposed algorithm SNACF-GA in that it considers only direct trust / distrust relationships. It also does not use GA optimization. The performances of the proposed algorithm and comparison models were evaluated by using average MAE (mean absolute error). Experimental result showed that the optimal adjusting coefficients for direct trust, indirect trust, direct distrust, indirect distrust were 0, 1.4287, 1.5, 0.4615 each. This implies that distrust relationships between users are more important than trust ones in recommender systems. From the perspective of recommendation accuracy, SNACF-GA (Avg. MAE = 0.111943), the proposed algorithm which reflects both direct and indirect trust / distrust relationships information, was found to greatly outperform a conventional CF (Avg. MAE = 0.112638). Also, the algorithm showed better recommendation accuracy than the SNACF (Avg. MAE = 0.112209). To confirm whether these differences are statistically significant or not, we applied paired samples t-test. The results from the paired samples t-test presented that the difference between SNACF-GA and conventional CF was statistical significant at the 1% significance level, and the difference between SNACF-GA and SNACF was statistical significant at the 5%. Our study found that the trust/distrust relationship can be important information for improving performance of recommendation algorithms. Especially, distrust relationship information was found to have a greater impact on the performance improvement of CF. This implies that we need to have more attention on distrust (negative) relationships rather than trust (positive) ones when tracking and managing social relationships between users.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.1-9
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• 1995

The slow development of histopathological changes and long period required for stabilization of lesions have suggested that secondary injury processes exacerbate the effect of initial mechanical insult after traumatic spinal cord injury (SCI). The importance of glutamate receptors in the normal functions of spinal cord, in concert with the large body of evidence that points to their involvement in neurotoxicity due to both ischemic and traumatic insults to the CNS, suggested a probable role of glutamate receptors in secondary injury process after traumatic SCI. In order to investigate the involvement of excitatory amino acid in the secondary injury process after SCI, this study examined the effect of dextrorphan, a noncompetitive NMDA receptor antagonist, on the recovery of hindlimb function and the residual tissue at injury site following SCI. Locomotor function was assessed using open field test (21 point scale). At 8 weeks spinal cord tissue was examined using quantitative histopathologic technique. Prior to surgery female Long-Evans rats were adapted to the test environment. Rats received laminectomies (T9/T10), and spinal cord contusions (NYU impactor) were produced by a 10 gm weight dropped 25 mm. DXT (15 or 30 mg/kg, i.p.) or saline was injected 15 min before contusion. Behavioral testing resumed 2 days post-injury and continued twice a week for 8 weeks. No differences between DXT and saline groups were found for hindlimb function and sparing tissue at the lesion site. These results suggest that NMDA receptor might not be involved in secondary injury processes after traumatic SCI.

• Journal of Life Science
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• v.15 no.5 s.72
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• pp.840-846
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• 2005

This study was carried out to investigate the effect of electron beam irradiation and cooking temperature on physico-chemical characteristics and lipid oxidation of beef. A total of six beef carcasses ($280\∼300 kg$) that were quality grade $1^{+}$(marbling score No.7, meat color No.4, maturity No.1, texture No.1) was purchased at the commercial slaughter house. The carcasses were transported and washed using high pressure water, and pasteulized with $ 50\% $ ethyl alcohol in the laboratory. After the carcasses were deboned and trimmed, loin and round were taken out to make steak (1.5cm thickness) or ground beef respectively. Samples were wrap or vacuum packaged and irradiated with 0, 3, 4.5, 6 and 7.5 kGy using electron-beam accelerator at Samsung Heavy Industries Ltd. Co. (in Taejun). Irradiated samples were cooked with different methods(electronic pan and gas oven) and temperatures ($ 60^{\circ}C, 70^{\circ}C and 80^{\circ}C$) and used to measure fatty acid composition, TBARS, cholesterol oxide products and panel test scores. The content of saturated fatty acids increased by increasing heating temperature in oven boiling steak (OBS) and pan boiling steak (PBS), and there was no difference by electron-beam irradiation. Both irradiated and non-irradiated treatment were high as the heating temperature increased in TBARS by heating temperature in PBS (p < 0.05) and the amount of Malonaldehyde (MA), standard of fat deterioration, was increased in OBS (p < 0.05). Non-irradiated and 3, 6 kGy treatment produced about 2 fold amount of MA at $ 60^{\circ}C $ compared with $ 80^{\circ}C $. In comparison with PBS, OBS produced much amount of MA and a bit different from non-irradiated treatment but did not show no tendency. As irradiation levels and heating temperature increased, the amount of cholesterol oxides products was increased and also pan-heating method, direct heating method, significantly increased the degree of oxidation compared with oven-heating method, indirect heating method (p < 0.05).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.285-294
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• 2003

To select an appropriate sampler for the environmental monitoring survey in coastal waters of Saemangeum, Jeollabuk-do, a macrobenthic sampling was conducted in April 2002. Employed samplers were dredge (type Charcot), a semi-quantitative sampler and Smith-McIntyre (SM) and van Veen grab (VV) as quantitative ones. One haul was tried for dredge and 3 replicates (0.1 ㎡${\times}$3) for SM and W at each of 11 stations. Comparisons of sediment volume in sampler bucket and of precision of biological parameters (i.e., density, biomass, species number and diversity index, H') were made between SM and VV. Sediment volume was significantly different (SM > VV) at p-value of 0.0050 (paired t-test) and, in average, 3 replicate samples of SM and VV satisfied a precision level of 0.2 by applying 4th root transformation. Patterns of observed and expected species numbers and H' were compared. Dredge-VV samples showed higher affinity than any other pair. Several dominant species in the area were underestimated in dredge samples (e.g., polychaete Heteromastus filiformis. Aricidea assimilis etc.). Quantifying the agreement pattern of multi-species responses was accomplished by estimating correlations between similarity matrices. Correlation between dredge and VV was slightly higher, but near-per-fect matches were found in general. Different ranks and composition among principal species lists were presumably linked to the effect of penetration depth that differs among samplers. Lower level of some species' abundance in VV samples (ca. 50％ compared with those of SM) was explained in this context. It seem appropriate to regard the effect as a probable cause of relatively higher correlations in dredge-VV, Overall bio-logica1 features indicated that a better choice could be SM in situations of requiring high data quality. The others work well, however, on observing and defining faunal characteristics and their capability cannot be questionted if we do not expect a first-order quality.

• Parasites, Hosts and Diseases
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• v.26 no.2
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• pp.73-86
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• 1988

The sensitivity and specificity of crude and affinity-purified antigens of Clcnorchis sinensis obtained from the infected rabbits were studied. Stage-specific antigenic proteins from the eggs, metacercariae and adult worms were characterized by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and enzyme-linked immunosorbent astray (ELISA). The results were as follows: 1. The antibody.binding antigen (ABA) purified from whole worm crude antigen (IVWA) by CNBr-activated Sepharose 4B affinity chromatography made :l specific bands against rabbit antisera on Ouchterlony gel diffusion plate, while WWA made 7 bands. Major WWA protein bands by SDS-PAGE were found at 16, 300~18, 500 and 28, 000~29, 000 daltons, while major ABA protein bands were at 18, 000~21, 000 and 29, 000~31, 000 daltons. The reactivity of ABA with rabbit anti-sera in ELISA was remarkably less sensitive than that of WWA. 2. Molecular weights of egg antigen (EGA), metacercarial antigen (MEA) and adult worm antigen (WWA) of C. sinensis ranged from 15, 000-200, 000 daltons, 15, 000-100, 000 daltons and 11, 000~80, 000 daltons, respectively. Major WWA proteins consisted mainly of polypeptide bands of low molecular weight, less than 31, 000 daltons, while those of EGA and MEA consisted of higher molecular T.eights than 30, 000 daltons. 3. The ELISA reactivities of WWA to rabbit anti.sera were remarkably greater than those of MEA. EGA showed negative reaction throughout the experiments. WWA showed higher optical density (O.D.) than 1.0, when reacted with rabbit anti-sera obtained at 4~6 weeks after the infection. In the rabbit anti-sera later than 12 weeks after the infection, the O.D. reacting witll WWA showed a plateau without variation. MEA shoT.ed relatively low O.D. values (<0.6), when reacted with anti-sera from lightly in(ected groups throughout the experiments, althougll there were some wealth positive cases (O.D.>0.6) ill heavily infected groups. MEA reacted with rabbit anti-sera showed negative results on Ouchterlony gel diffusion plates. Summarizing the above results, it is suggested that the whole worm antigen prepared from the adult worms of C. sinensis is most highly antigenic. However, this antigen might reveal cross reactions with other trematodes such as Paragonimus westermani, therefore, purification of antigenic proteins from the crude antigen is essential 18 increase the sensitivity and specificity for the immuncdiagnosis of clonorchiasis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4863-4872
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• 2010

This study examined the disease conditions of patients from a farming and fishing village area. In order to analyze the medical service utilization, the necessary data were obtained from established health and medical care service plans from medical treatment related organizations. The following results were based on the analysis of data from the medical records of 2,365 discharged patients during a six months period from July to December 2009 at a general hospital in an aging farming and fishing village area. Results: The sex of the patients investigated was male 55.3%, female 44.7%, and the most frequent age category at 42.0% was 70 years of age or older. Based on type of hospital admission, 65.5% of patients who were admitted were originally outpatients. Patients were admitted according to the following departments: 49.7% for the department of internal medicine, 16.7% for the department of orthopedics, and 13.8% for the department of neurosurgery. The average number of days hospitalized was 14.8 days. The following ranks the principal diagnosis among patients in this study: S00-T98 18.4%, J00-J99 15.5%, and I00-I99 11.5%. The average number of diagnosis listed per patient was 5.6. There was a statistically significant difference for the following general characteristics according to principal diagnosis list: gender, type of insurance, admission process, and age category distribution had statistically significant differences. Monthly distribution of principal diagnoses were statistically significant difference. There was a statistically significant difference for principal diagnosis lists according to the average number of days admitted and the number of diagnosis. The results of this study showed the types of disease from typical farming and fishing village regions as disease from external injury due to the work environment of farming and fishing village regions and excessive labor throughout the year, respiratory disease, and various chronic disease from aging.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.3
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• pp.159-170
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• 2006

Objective: The purpose of this study is to find out risk factors related to uterine leiomyoma in Korean women and to compare with the results of previous western studies. Methods: A retrospective analysis was carried out. All the cases of uterine leiomyoma (n=244) were diagnosed surgically or sonographically between Jannuary 1998 and December 2004. Total of 269 controls not having uterine leiomyoma were collected from patients who visited Kyungpook national university hospital for routine gynecologic check-up or treatment of their gynecologic or obstetric diseases other than uterine leiomyoma. Data were collected through review of medical records and interviews and analyzed with $x^2$ and logistic regression model. Results: In multivariate analysis, patient's age (OR 1.070; 95% CI 1.041~1.099), number of artificial abortion (OR 1.182; 95% CI 1.018~1.374) and alcohol drinking (OR 1.865; 95% CI 1.231~2.824) had significantly positive correlation with uterine leiomyoma. The duration of lactation was the only factor which had negative correlation (OR 0.985; 95% CI 0.972~0.998). BMI, parity, age at menarche, the duration and interval of menstruation, caffeine consumption and marital status did not show any correlations. Conclusion: In this study, patient's age, number of artificial abortion, and alcohol drinking were the risk factors of uterine leiomyoma in Korean women and the result was similar to that of western studies. Though we couldn't find out the specific risk factors related to the development of uterine leiomyoma in this study, but it has a great meaning to be the first trial in Korean women. The role of information bias should be carefully evaluated and further multicentered, randomized, controlled prospective studies will be needed to know the possible risk factors among Korean women.

• Journal of Science Education
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• v.41 no.3
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• pp.334-350
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• 2017

The purposes of this study are to develop scientific-inquiry based on STEAM education program and to investigate the effects of the program on middle-school students' interests, self-efficacy, and career choice about science, technology/engineering, and mathematics. In order to develop this program, the literature investigation and previous studies were conducted, so that finally the developmental direction was based on scientific inquiry and the developmental theme and model were selected. A total 92 first-graders in G middle-school of Daegu city were participated in this study. A single group pre-post test paired t-test was conducted to figure out changes of students' interest, self-efficacy, and career choices before or after applying this program. In addition, in-depth interviews were conducted with 14 students to find their specific responses. The results of this study were as follows. First, STEAM education program on the theme of 'RC Airplane' was developed on the basis of the 'ADBA' model. Second, the developed STEAM educational program not only results a decisive difference statistically but also has significant effects on middle-school students' interests, self-efficacy, and career choice in science, technology/engineering, and mathematics, who are involved in the free-semester program, across the overall affective domain. In conclusion, the STEAM educational program in this study could affect significant meanings to middle-school students during the free-semester. It could contribute to facilitate middle-school students' education for happiness and to grow the creative STEAM talents.

• Economic and Environmental Geology
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• v.34 no.4
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• pp.375-383
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• 2001

We extracted sea surface heights(SSH) from the TopexJPoseidon(T/P) radar altimeter data to compare with fhe SSH estimated from in-situ lide gauges(T/G) at Ulleungdo, Pohang, and SockcholMucko sites. Selection criteria such as wet/dry troposphere, ionosphere, and ocean tide were used to estimate accurate SSH. For time series analysis, the one-hour interval tide gauge SSHs were resampled al lO-day interval of the satellite SSHs. The ocean tide model applied in the altimeter data processing showed periodic aliasings of 175.5 day, 87.8 day, 62J day, 58.5 day, 49.5 day and 46.0 day, and, hence, the ZOO-day filtering was applied to reduce these spectral noises. Wavenumber correlation analysis was also applied to extract common components between the two SSHs, resulting in enhancing the correlation coefficient(CC) dramatically. The original CCs between the satenite and tide gauge SSHs are 0.46. 0.26, and 0.]5, respectively. Ulleungdo shows the largest cc bec;luase the site is far from the coast resulting in the minimun error in the satellite observations. The CCs were then increased to 0.59, 030, and 0.30, respectively, after 200.day filtering, and to 0.69, 0.63. and 0.59 after removing inversely correlative components using wavenumber correlation analysis. The CCs were greatly increased by 87, 227, and 460% when the wavenumber correlation analysis was followed by 2oo-day filtering, resulting in the final CCs of 0.86, 0.85, 0.84, respectively. It was found that the best SSHs were estimated when the two methods were applied to the original data. The low-pass filtered TIP SSHs were found to be well correlated with the TIG SSHs from tide gauges, and the best correlation results were found when we applied both low-pass filtering and spectral correlation analysis to the original SSHs.

• Korean Journal of Animal Reproduction
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• v.24 no.2
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• pp.189-197
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• 2000

In this study, we investigated the preventive and therapeutic effects of antler-extract for osteoporosis. Rats were ovariectomized bilaterally and were fed up with Ca- and P-free diet in order to induce osteoporosis. Body weight, organ weight, the weight of femur and bone ash quantity were examined for 5 weeks. We also performed histological and electronical microscopic examinations. 1. After adminstration of female and male antler extract to osteoporosis-induced rats at the doses of 625 and 1250 mg/kg, respectively, the body weights were significantly increased compared with those of normal control group's which was 230.2:t2.3-281.0:t2.5g (p＜0.05). 2. The weights of both right and left femur of osteoporosis-induced rats, administered with female or male antler-extract, little decreased compared with those of normal control group. 3. The bone ash quanties of femur of osteoporosis-induced rats, administered with female or male antler-extract, little decreased compared with those of normal control group. 4. The weights of liver, spleen, and kidney of osteoporosis-induced rats, administered with female or male antler-extract, decreased compared with those of normal control group. 5. Histological and electronic microscopical findings were (1) that in normal control rats the connectional of lacunae appeared well and were without loss of bone mineral, (2) that in ovariectomized rats the connections of lacunae were mostly broken and were with loss of bone mineral compared with those of normal control rats, (3) that in osteoporosis-induced rats, administrated with female or male antler-extract, the shape of lacunae and the connections of them were similar to those of normal control rats. These findings suggest a possible protective and therapeutic effects of female or male antler extract against bone loss in ovariectomized rats.