• 무역학회지
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• 제45권3호
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• pp.55-69
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• 2020

This study examines the research trends and knowledge structure of international trade studies using topic modeling method, which is one of the main methodologies of text mining. We collected and analyzed English abstracts of 1,868 papers of three Korean major journals in the area of international trade from 2003 to 2019. We used the Latent Dirichlet Allocation(LDA), an unsupervised machine learning algorithm to extract the latent topics from the large quantity of research abstracts. 20 topics are identified without any prior human judgement. The topics reveal topographical maps of research in international trade and are representative and meaningful in the sense that most of them correspond to previously established sub-topics in trade studies. Then we conducted a regression analysis on the document-topic distributions generated by LDA to identify hot and cold topics. We discovered 2 hot topics(internationalization capacity and performance of export companies, economic effect of trade) and 2 cold topics(exchange rate and current account, trade finance). Trade studies are characterized as a interdisciplinary study of three agendas(i.e. international economy, International Business, trade practice), and 20 topics identified can be grouped into these 3 agendas. From the estimated results of the study, we find that the Korean government's active pursuit of FTA and consequent necessity of capacity building in Korean export firms lie behind the popularity of topic selection by the Korean researchers in the area of int'l trade.

• 수산해양기술연구
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• 제30권4호
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• pp.239-250
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• 1994

The vertical distribution and activity patterns of fishes during the evening and morning transitions between day and night were studied acoustically and by bottom trawling in November 1990-1992 in thermally stratified waters of the East China Sea. The acoustic data were collected from six stations with a scientific echo-sounder operating at two frequencies of 25 and 100kHz, and the echograms were used to determine the vertical distributions of fish. Biological sampling was accomplished by bottom trawling to identify fish species recorded on the echograms, and the species and length compositions were determined. At each station, vertical profiles of water temperature, salinity and dissolved oxygen were taken with a CTD system and were related to the diel movements and the depth distributions of fish. During the day most fish were within several meters above bottom, but began to migrate upwards just before sunset, and during the night they were dispersed in midwater. Prior to sunrise with a thermocline present, one group of the fish aggregation occurred in dense schools slightly above the thermocline, while the other group occurred with the numerous single fish-traces bellow it. These groups of aggregations rapidly began to migrate toward the bottom across the thermocline from about 40 min before sunrise. Trawl hauls in the bottom strata below the thermocline with the characteristic single fish traces yieled invariably catches dominated by snailfish and fishing frog with minor quantities of other species in all stations. Hence, the results indicate that snailfish and fishing frog were the dominated scatterers in the depth strata below the thermocline, and the single-fish recordings were mainly snailfish. The fish species such as anchovy and juvenile mackerel in bottom trawl catches is poorly represented in relation to the mesh selectivity of the trawl net, but their occurrence suggest that the fish-school recording above the thermocline were due to these species which migrated vertically across the thermocline, with a temperature gradient of about 8$^{\circ}C$, from the water layers near the bottom at night. Accordingly, we conclude that the vertical distribution and activity patterns of snailfish were strongly temperature dependent and in the termally stratified waters, the upper limit to diel activity was closely linked to the position of the thermocline.

• 대한교통학회지
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• 제22권4호
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• pp.31-42
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• 2004

본 논문에서는 철도건널목에서 일어나는 사고를 줄이기 위해 새롭게 시도되는 개선대안(Countermeasure)들의 안전성 및 효율성을 베이지안 분석방법론을 이용하여 안전전문가들의 평가결과를 정량화 시키는 방법론을 제시하였다. 이를 위해 전문가 개개인의 사전지식에 논리에 기초한 정보를 제공할 수 있는 개선대안 분석방법론을 개발하였다. 분석방법론은 우선적으로 철도건널목 안전성을 향상 시킬 수 있는 개선대안 선정, 개선대안을 평가 할 전문가 선정, 그리고 개선대안의 AMF를 평가하기 위한 건널목 사고를 선정하였다. 다음 단계로 안전전문가가 공학적인 개선대안 평가를 수행할 수 있도록 사고이력매뉴얼과 개선대안 평가매뉴얼을 개발하였다. 마지막 단계로, 평가된 개선대안의 통계적 검정을 통해 합리적 AMF를 추출함에 따른 정량화된 안전도를 나타내었다. 개선대안의 통계적 검정은 비모수통계분석의 일종인 Kolmogorov-Smirnov(K-S)동질성 검정을 적용하였으며, 그 결과 안전전문가 개인간의 분포는 동일한 분포를 나타내지 않는 경우가 많이 발생하였다. 반면 개인과 그룹의 분포는 대부분 동일한 분포를 하고 있는 것으로 나타났다. 따라서 철도건널목 개선대안의 AMF값은 전문가 개개인이 평가한 값을 전체적으로 평균한 값을 사용함이 타당한 것으로 연구되었다. 본 논문에서 보여주는 AMF의 정량화과정은 철도건널목에서 뿐만 아니라, 교차로 및 도로구간에서 추후 시도되고자 하는 개선대안들의 안전성 평가에도 사용 가능하리라 판단된다.

• 감성과학
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• 제16권3호
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• pp.363-372
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• 2013

폭소노미 (foxonomy) 분위기 태그를 이용한 음악 검색 시 내부적으로 단어 태그 대신에 수치 태그 (AV 태그: Arousal과 Valence 값으로 이루어진 태그)를 이용하면 폭소노미의 문제점 중의 하나인 유사어 문제점을 일부 해결할 수 있다. 하지만 이를 위해서는 두 가지 선행 작업이 제대로 이루어져야 하는데, 그 첫 번째가 단어 태그를 수치 태그로 변환하는 작업이며 그 두 번째가 검색 대상인 음악을 수치 태그로 표현하는 작업이다. 첫 번째 작업에 대해서는 이전 연구를 통하여 그 유의성을 보였기 때문에 본 논문에서는 두 번째 작업에 대해서 그 유의성을 밝히고자 하였다. 이를 위하여 본 논문에서는 음악과 AV값 간의 관계를 정의하는 음악-분위기 매핑테이블을 제안하고, ANOVA 검증을 이용하여 분석 하였다. 실험 결과, 동의어 포함 유무에 무관하게 음악 구간의 A값과 V값 모두 12개 음악의 분위기에 대하여 분포차가 발생하고, 모두 제 1종 오류확률 P<0.001를 만족하였다. 결론적으로 음악의 분위기에 따라 AV 값 분포가 다르다는 것을 확인할 수 있었다.

• 콘크리트학회논문집
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• 제26권4호
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• pp.449-456
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• 2014

지오폴리머 반응은 매우 복잡하며, 플라이애쉬 화학조성, 입도분포, 자극제 농도와 종류, 양생온도, 양생시간 등이 지오폴리머 물성에 많은 영향을 미치고 있는 것으로 알려져 있다. 이 연구에서는 양생조건이 플라이애쉬 기반 지오폴리머 강도에 미치는 영향을 실험하기 위하여, 양생온도, 고온양생 전 전치시간, 고온에서의 양생시간 등을 변화시켜 양생조건 변화에 따른 지오폴리머 페이스트의 압축강도, SEM, 공극특성 등에 대하여 분석하였다. 실험 결과 양생온도가 높을수록 지오폴리머의 강도는 증가하였으며, 전양생시간이 길어질수록 지오폴리머 강도는 증가되었으나, 고온양생에서의 양생시간이 길어지면 압축강도가 저하현상이 관찰되었다. 고온에서의 양생시간이 길어지면 공극구조의 변화에 따라 강도 저하 현상이 관찰되었다. 따라서 양생온도와 양생시간은 지오폴리머 강도 및 미세구조에 큰 영향을 미치고 있는 것을 확인할 수 있었다.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.585-593
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• 2006

The effect of the shape of the side wall on vaporization and fuel mixture were investigated for the impinging spray of a direct injection(DI) gasoline engine under a variety of conditions using the LIEF technique. The characteristics of the impinging spray were investigated under various configurations of piston cavities. To simulate the effect of piston cavity configurations and injection timing in an actual DI gasoline engine, the parameters were horizontal distance from the spray axis to side wall and vertical distance from nozzle tip to impingement plate. Prior to investigating the side wall effect, experiments on free and impinging sprays for flat plates were conducted and these results were compared with those of the side wall impinging spray. For each condition, the impingement plate was located at three different vertical distances(Z=46.7, 58.4, and 70 mm) below the injector tip and the rectangular side wall was installed at three different radial distances(R=15, 20, and 25 mm) from the spray axis. Radial propagation velocity from spray axis along impinging plate became higher with increasing ambient temperature. When the ambient pressure was increased, propagation speed reduced. High ambient pressures tended to prevent the impinging spray from the propagating radially and kept the fuel concentration higher near the spray axis. Regardless of ambient pressure and temperature fully developed vortices were generated near the side wall with nearly identical distributions, however there were discrepancies in the early development process. A relationship between the impingement distance(Z) and the distance from the side wall to the spray axis(R) was demonstrated in this study when R=20 and 25 mm and Z=46.7 and 58.4 mm. Fuel recirculation was achieved by adequate side wall distance. Fuel mixture stratification, an adequate piston cavity with a shorter impingement distance from the injector tip to the piston head should be required in the central direct injection system.

• 한국임상수의학회지
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• 제25권4호
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• pp.227-230
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• 2008

To determine the distribution of feline blood types and then to estimate the risk of neonatal isoerythrolysis (NI) in non-pedigree cats, we typed blood of 482 cats of both genders and various breeds (336 domestic shorthair cat and 146 pedigree) from August 2005 through July 2007. Blood samples from Seoul and Kangwon province were typed within 5 days after collection by the simple tube method. High-titer anti-A antiserum and anti-B reagent, prepared with Triticum vulgaris lectin, were used to determine type A and type B blood, respectively. The majority of cats were type A (n = 465, 96.5%) and only 3.5% (n = 17) were type B. No type AB blood were detected. Blood type distributions among the non-pedigree and pedigree cats were similar: for non-pedigree cats, 96.4% were type A and 3.6% were type B, whereas for pedigree cats, 96.6% were type A and 3.4% were type B. All type B cats had a very strong agglutination reaction to anti-A antiserum: 8 sample for 3+ and 9 for 4+. Assuming 19% of estimated frequency for the type-B allele in domestic cats, the calculated proportion of random mating from this population at risk for developing NI was 3.4%. Based on this finding, it is strongly recommended that blood typing be performed prior to any blood transfusion or breeding to minimize blood type incompatibilities. Further comprehensive studies on the titer of naturally occurring antibodies in cat populations in Korea and the prevalence of possible NI in practice are clearly required.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8221-8226
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• 2016

Background: Misreporting self-reported family history may lead to biased estimations. We used Bayesian methods to adjust for exposure misclassification. Materials and Methods: A hospital-based case-control study was used to identify breast cancer risk factors among Iranian women. Three models were jointly considered; an outcome, an exposure and a measurement model. All models were fitted using Bayesian methods, run to achieve convergence. Results: Bayesian analysis in the model without misclassification showed that the odds ratios for the relationship between breast cancer and a family history in different prior distributions were 2.98 (95% CRI: 2.41, 3.71), 2.57 (95% CRI: 1.95, 3.41) and 2.53 (95% CRI: 1.93, 3.31). In the misclassified model, adjusted odds ratios for misclassification in the different situations were 2.64 (95% CRI: 2.02, 3.47), 2.64 (95% CRI: 2.02, 3.46), 1.60 (95% CRI: 1.07, 2.38), 1.61 (95% CRI: 1.07, 2.40), 1.57 (95% CRI: 1.05, 2.35), 1.58 (95% CRI: 1.06, 2.34) and 1.57 (95% CRI: 1.06, 2.33). Conclusions: It was concluded that self-reported family history may be misclassified in different scenarios. Due to the lack of validation studies in Iran, more attention to this matter in future research is suggested, especially while obtaining results in accordance with sensitivity and specificity values.

• The Journal of Advanced Prosthodontics
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• 제5권3호
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• pp.256-261
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• 2013

PURPOSE. Occlusal splints are commonly used to prevent tooth wear caused by bruxism. However, the effects of splints on occlusion are still unclear. Although it is rarely alluded in literature, splints can provoke severe occlusal alterations and other complications. This study was aimed to identify differences in the responses of individuals with bruxism and healthy individuals to a full-arch maxillary stabilization splint in terms of occlusal changes. MATERIALS AND METHODS. Occlusal contacts in 20 (5 male, 15 female) bruxism patients and 20 (5 male, 15 female) controls with normal occlusion were evaluated before and after occlusal splint therapy. T-Scan III, a computerized occlusal analysis system, was used to simultaneously measure occlusion and disclusion times as well as left-right and anterior-posterior contact distributions before splint therapy and 3 months after therapy. Wilcoxon and Mann-Whitney U tests were used for statistical analyses (${\alpha}$=.05). RESULTS. No differences were found in the posterior contact of bruxism patients before and after stabilization splint treatment. However, differences in posterior contact were observed between bruxists and normal individuals prior to treatment, and this difference disappeared following treatment. CONCLUSION. The results of this study showed the use of a stabilization splint may not have an effect on occlusion. However, the area of posterior occlusal contact among bruxists was found to be greater than that of normal individuals. According to this study, the clinical use of splints may be harmless.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4814-4834
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• 2018

This paper presents an architecture for wireless sensor networks (WSNs) with blind source separation (BSS) applied to retrieve the received mixing signals of the sink nodes first. The little-to-no need of prior knowledge about the source signals of the sink nodes in the BSS method is obviously advantageous for WSNs. The optimization problem of the BSS of multiple independent source signals with complex and noncircular distributions from observed sensor nodes is considered and addressed. This paper applies Castella's reference-based scheme to Novey's negentropy-based algorithms, and then proposes a novel fast fixed-point (FastICA) algorithm, defined as the reference-signal negentropy complex FastICA (RSNT-cFastICA) for complex-valued noncircular-distribution source signals. The proposed method for the sink nodes is substantially more efficient than Novey's quasi-Newton algorithm in terms of computational speed under large numbers of samples, can effectively improve the power consumption effeciency of the sink nodes, and is significantly beneficial for WSNs and wireless communication networks (WCNs). The effectiveness and performance of the proposed method are validated and compared with three related BSS algorithms through theoretical analysis and simulations.