• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.49-56
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• 2018

As the energy generated by earthquake, tsunami, etc. propagates through the air and disturbs the electron density in the ionosphere, the perturbation can be detected by analyzing the ionospheric delay in satellite signal. The electron density in the ionosphere is affected by various factors such as solar activity, latitude, season, and local time. To distinguish from the anomaly, therefore, it is required to inspect the normal trend of the ionosphere. Also, as the perturbation magnitude diminishes by distance it is necessary to develop an appropriate algorithm to detect long-distance disturbances. In this paper, normal condition ionosphere trend is analyzed via IONEX data. We selected monitoring value that has no tendency and developed an algorithm to effectively detect the long-distance ionospheric disturbances by using the lasting characteristics of the disturbances. In the end, we concluded the $2^{nd}$ derivative of ionospheric delay would be proper monitoring value, and the false alarm with the developed algorithm turned out to be 1.4e-6 level. It was applied to 2011 Tohoku earthquake case and the ionospheric disturbance was successfully detected.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1172-1178
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• 2011

The purpose of this study was to investigate the status of a school foodservice menu evaluation and the perception of the school's dietitian on menu evaluation. Questionnaires were distributed to 448 school dietitians with an official letter, and a total of 292 responses were used for analysis. More than 90% of the respondents stated that a menu evaluation for the school foodservice was necessary. The major barriers to menu evaluation were "excessive workload" and a "lack of know-how", and the expected benefits were "increased satisfaction of customers" and "increased foodservice efficiency". The menu evaluation for "student preferences", "health improvement", and "ease of quality management" categories were performed in more than 45% of schools. The proportion of subjects who answered that "customer satisfaction" and "increased efficiency of foodservice" were expected benefits of menu evaluation were significantly higher in the menu evaluation group (p<0.05).

• Korean Journal of Environment and Ecology
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• v.28 no.1
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• pp.24-32
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• 2014

Our study is purposed to understand effect on spatio-temporal variability of macroinvertebrate community 11 sampling times at 4 sites between two streams (Shinchon stream and Gongji stream in Chuncheun City) from May 2011 to October 2013. In this study, the possible physical factors on spatio-temporal variability of macroinvertebrate community were discussed. After stream improvement project, the effects of anthropogenic disturbance in study sites appeared as increased water temperature more than $30^{\circ}C$ and the difference of water temperature between Shinchon stream and Gongji stream was by maximum $9^{\circ}C$ on 2012. The monsoon rainfall decreased number of species, individuals and biodiversity index of macroinvertebrate community, particularly, in Shincheon stream compare to Gongji stream. Dominant species of macroinvertebrate taxa was caddisfly in Shincheon stream and Diptera in Gongji stream but on August 2013, it was dominated by Diptera, Chironomidae spp. in all study sites. The spatio-temporal variability of macroinvertebrate community in the streams may be useful as bio-indicator influencing anthropogenic factors such as soil erosion (landslide or cultivation) or monsoon rainfall.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.356-360
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• 2010

Recently, there have been many research efforts on privacy-preserving data mining. In privacy-preserving data mining, accuracy preservation of mining results is as important as privacy preservation. Random perturbation privacy-preserving data mining technique is known to well preserve privacy. However, it has a problem that it destroys distance orders among time-series. In this paper, we propose a notion of the noise averaging effect of piecewise aggregate approximation(PAA), which can be preserved the clustering accuracy as high as possible in time-series data clustering. Based on the noise averaging effect, we define the PAA distance in computing distance. And, we show that our PAA distance can alleviate the problem of destroying distance orders in random perturbing time series.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1240-1245
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• 2006

PCB는 수십개의 주공정과 보조공정으로 구성된 제품으로 동일한 생산라인에서 로트 단위로 다품종 혼류 생산되고 있다. 따라서 PCB 제조라인에서는 많은 공정수, 높은 불량률, 다양한 공정설비 및 빈번한 설비고장, 중소기업의 낮은 설계 및 생산기술력, 빈번한 수주 변경 및 다품종 혼류, 긴급 수주 등과 같이 제조원가를 증가시키는 다양한 교란요인들이 항상 발생하고 있다. 본 연구에서는 생산성, 품질 등을 고려하면서 리드 타임을 단축하기 위하여 TOC DBR 기법을 개선한 2개의 DBR 개념을 도입하여 성공적으로 리드타임을 개선한 사례를 소개하고자 한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.499-509
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• 2006

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail, acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses for the frequently adopted PSC composite girder railway bridge. The effect of the temperature change is also investigated considering the design codes and theoretical equations in an in-depth manner. The estimated proper prestress level to counteract those tensile stresses is above 2.4 MPa, which is similar to the case of the highway bridges.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.713-718
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• 2021

This study was conducted to clarify the role and importance of dental hygienists in improving patient satisfaction in dental medical institutions, and to improve the social position, working conditions, and environment of dental hygienists. This study evaluated the impact of dental hygienists on dental satisfaction, revisits, and doctor recommendations for patients who had received prosthodontic treatment at dentistry in the last 10 years. This study analyzed the data from 166 survey questionnaires from June 1, to July 2, 2020. For data analysis, the SPSS Ver 23.0 program was used to calculate frequency and percentage, mean and standard deviation of the variables, Pearson correlation analysis, and multiple regression analysis. As a result, the average quality of medical services provided by dental hygienists among prosthetics was 4.05, the average dental satisfaction was 4.27, the average revisit was 3.97, and the average recommendation was 4.01. As a result of Pearson's correlation analysis, there was a significant positive correlation between each variable (P<0.01). As a result of multiple regression analysis, the level of knowledge appeared as a factor affecting dental satisfaction (P<0.05). The factors influencing both the revisits and the intention to recommend were the level of knowledge and the level of education (P<0.05).

• Life and Agrochemicals
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• s.263
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• pp.14-17
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• 2010

무역자유화 시대의 한국 농업의 유지, 발전의 관건은 가격 이외의 요인으로 부가가치를 높이고 농산업이 수행하고 있는 다양한 비경제적 기능을 국민 전체가 인정하고, 그 결과 합리적인 소득지지정책이 뒷받침 될 때만이 한국 농산업이 건전한 발전과 농촌지역의 지속 가능성이 담보될 것이다.

• 대한핵의학회:학술대회논문집
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• 2002.11a
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• pp.20.1-20.1
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• 2002

• Journal of Wetlands Research
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• v.22 no.4
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• pp.295-301
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• 2020

This research analyzed the relationship between environmental factors and the density of Sycios angulatus in the Miho Stream, Geum River water system in order to secure basic data for the control of the ecosystem-distrubing plant Sycios angulatus. As a result of the soil particle size analysis of Sycios angulatus habitat, it was found that the density of Sycios angulatus decreased as the silty and clay contents increased. Most of the Sycios angulatus habitats had high sandy and silt content, and low clay content of less than 2%. The increased flow rate reduced the density of Sicyos angulatus. This is because when the flow rate is increased, the Sicyos angulatus cannot grow due to the change in soil characteristics. Water quality plays a role in supplying nutrients when Sicyos angulatus are submerged. However, due to the change in soil characteristics during flooding, the density of Sicyos angulatus tended to decrease due to impaired growth. The Sicyos angulatus can be managed through artificial and natural techniques. The appropriate natural control technique is the creation of a natural waterway in the habitats to change the water contents.