• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.387-388
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• 2009

In concrete cable-stayed bridge, the time-dependent effects of concrete should be taken into account for the optimum cable force adjustment. The method for estimating the creep coefficient with using the deflections and the cable forces in concrete cable-stayed bridge is presented and the effects of the creep coefficient error are analyzed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1475-1485
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• 2012

This study was conducted in order to understand nutrition teachers (dietitians)' perceptions of barriers to implementation of HACCP system in school foodservices in Gyeongnam, Korea. Questionnaires were distributed to 350 nutrition teachers (dietitians) from November to December of 2009, and 214 were collected and analyzed. The results of this study were as follows. First, nutrition teachers (dietitians) recognized the following as barriers in implementing the HACCP system: 'the status of facilities and utilities'> 'monitoring'> 'work satisfaction'> 'foodservice employees'> 'cooperation of HACCP team'> 'cooperation of persons concerned besides foodservice employees'> 'understanding the HACCP system'. Second, total working experience was found to be the factor most affecting 'cooperation of HACCP team (p<0.01)', 'cooperation of persons concerned besides foodservice employees (p<0.01)', 'foodservice employees (p<0.05)', and 'work satisfaction (p<0.05)'. Further, 'the status of facilities and utilities' was significantly affected by 'construction/reconstruction of kitchen (p<0.01)', 'division of kitchen area (p<0.01)', 'existence of preliminary preparation room (p<0.01)', and 'existence of dishwashing room (p<0.01)'. Third, dietitians perceived the following concerning hindrance factors of the HACCP system according to CCP stage: 'CCP 1'> 'CCP 3'> 'CCP 2, 'CCP 6'> 'CCP 4'> 'CCP 8'> 'CCP 7'> 'CCP 5'. In conclusion, this study showed that nutrition teachers (dietitians) in the Gyeongnam area recognized 'the status of facilities and utilities' from HACCP areas and 'CCP 1 (menu planning)' from CCP stages as the greatest barriers to implementing the HACCP system in school foodservices. To implement the HACCP system successfully in school foodservices, facilities and utilities should be properly equipped, and menu planning training for nutrition teachers (dietitian) should be conducted.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.103-111
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• 2016

Seasonal dynamics of kelp forest-forming algae, Ecklonia cava population formed following the large-scale disturbance by Typhoon 'Bolaven' in August 2012 were investigated in Jeju Island, Korea. Morphological characteristics, recruits density, mortality rate, total density and biomass were monitored bimonthly from June 2013 to June 2015. Total and longest blade lengths, and individual weight of E. cava showed distinct seasonal trends. Stipe length increased from winter to spring, but did not show increase or reduced from summer to autumn. This indicates that morphological characteristics of E. cava are mainly affected by the change of blades. The optimal temperature for E. cava growth was about $15-18^{\circ}C$ during winter to spring while the growths were inhibited at the water temperature above $20^{\circ}C$ during summer. E. cava exhibited very low recruitment during spring-summer. However, high recruitment was observed on April 2015 when canopy cover was very low due to low density. This indicates that recruitment of E. cava was controlled not by seasonal effects but by physical factors such as canopy and space. The mortality rate of juvenile plants was highest due to their unstable settlement. By June 2015, 34 months after the disturbances, E. cava was almost recovered to the pre-disturbance population size structure. These results suggest that recovery of kelp forest following the large-scale disturbance requires a considerable period of time (more than three years). This study should provide valuable ecological information on management, restoration and protection of kelp species.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1693-1705
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• 2013

To restore old aqueduct in Korea which is a irrigation bridge to supply water in paddy field area, it is needed to estimate approximate costs of restoration because the basic design for estimation of construction costs is often ruled out in current system. In this paper, estimating models of construction costs were developed on the basis of performance data for restoration of RC aqueduct bridges since 2003. The regression analysis (RA) model and case-based reasoning (CBR) model for the estimation of construction costs were developed respectively. Error rate of simple RA model was lower than that of multiple RA model. CBR model using genetic algorithm (GA) has been applied in the estimation of construction costs. In the model three factors like attribute weight, attribute deviation and rank of case similarity were optimized. Especially, error rate of estimated construction costs decreased since limit ranges of the attribute weights were applied. The results showed that error rates between RA model and CBR models were inconsiderable statistically. It is expected that the proposed estimating method of approximate costs of aqueduct restoration will be utilized to support quick decision making in phased rehabilitation project.

• 대학교육
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• s.148
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• pp.37-43
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• 2007

대학은 자유로운 교과를 가르치는 데 목적을 둘 것인지, 아니면 유용한 교과를 가르치는 데 역점을 둘 것인지를 분명히 해야 한다. 그렇지 않으면 이 둘의 조화를 꾀하든지 말이다. 그러나 대학과 교육과정을 구분하는것이 자칫 자유로운 교과와 유용한 교과, 이론과 실제를 배타적인 논리로 잘못 이해되는 일은 없어야 할 것이다. 대학을 온통 취업 시장으로 만들어야 한다는 뜻을 반드시 포함하지도 않는다는 사실과 함께 말이다.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.308-319
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• 2016

In order to evaluate the role of macrophytes as refuge of zooplankton on physical distribution (i.e. summer rainfall), we investigated the environmental factors, macrophytes, and zooplankton in waterside zones (macrophytes zones) and open water zones of 17 wetlands from May and August, 2011. In this study, a total of 51 zooplankton species were identified, and Polyarthra sp. and Diaphanosoma brachyurum were found to be the most dominant species. Waterside area of each wetland were occupied by a total of 10 macrophyte species, species composition and biomass (dry weight) were different in the survey sites. Zooplankton was more abundant in waterside zone than open water zones lacking macrophytes (One-way ANOVA, df=2, F=27.1, P<0.05), in particular, waterside zone of 1, 8, 9, 10, and 11 wetland were supported by high zooplankton density after summer rainfall. This wetlands were developed by various macrophyte species than other wetland, and submerged plant commonly presented. Waterside zones with various macrophyte species provides complexity to the habitat structure, should be utilized as refuge to avoid disturbance such as summer rainfall. The results indicate that macrophytes are the key components to enhance bio-diversity include zooplankton, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.36-36
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• 2019

본 연구는 한라산국립공원 동사면에 위치한 구상나무숲 장기생태 모니터링 5ha 조사지역 ($20{\times}20m$, 125개 방형구)에서 구상나무의 유묘 및 치수 발생 현황을 파악하기 위하여 수행되었다. 조사는 2016년 6~8월 사이에 $5{\times}5m$ 방형구 125곳에 대해 계통추출법을 적용하여 실시하였다. 조사한 전체 125개 방형구 중에서 54개에서만 유묘가 관찰되었으며, 그 내용은 유묘 615개체 및 치수 1개체로 총 616개체가 발견되었다. 그러나 과반수의 71개 방형구에서 치수뿐만 아니라 유묘도 출현하지 않았다. 심지어 전체 125개 방형구에서 유묘가 가장 많이 관찰된 방형구(2-6지역, 95개체)를 제외하면, 나머지 124개 방형구의 평균 유묘 개체수는 4.2개로 매우 적었고 높이도 35cm 이하에 불과했다. 이와 함께 장기생태 모니터링 조사 지역 내에서 $1{\times}1m$ 방형구 183곳에 대해 단순 무작위 추출법으로 발생지 조사를 수행하였다. 발생지 조사 결과 유묘 2,518개체, 치수 2개체 및 유목 2개체 등 총 2,522개체가 발견되어 계통추출법을 적용한 조사와 유사한 결과가 나타났다. 본 연구를 통해 한라산국립공원 동사면 구상나무숲 내에서 구상나무 유묘의 발생은 어느 정도 이루어지고 있으나, 교란으로 인하여 치수로의 발달이 제한되는 것으로 판단된다. 여러 교란 요인 중에서 조사된 총 3,138개체 중 12.1%, 381개체에서 유제류인 노루에 의한 섭식이 확인되어 노루의 섭식이 유묘 발생 및 치수 발달에 교란을 야기하는 가장 중요한 요인으로 추정해볼 수 있다. 한반도 특산식물 구상나무의 보전 대책 수립을 위한 유묘 및 치수 교란 원인에 대한 지속적인 모니터링이 진행되어야 한다고 사료된다.

• Journal of the Korean Chemical Society
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• v.64 no.2
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• pp.119-129
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• 2020

For effective teaching-learning activities for students with diverse talents in science high schools, it is important for teachers to understand students' individual differences in perceiving and processing information in the natural world, depending on the students' various talents and subject characteristics. The purpose of this study is to examine the students' cognition of chemistry in science high school through correlations and factor analysis of mathematics/science achievement. In addition, this study attempted to examine the cognition of chemistry subject according to R&E classes. The main participants of the study were freshmen of G science high school (296 students) who entered after three times of curriculum reforms and new admission processes and the students in two other science high schools in Gyeongnam and Ulsan were included. The correlation and factor analysis were conducted by exploratory factor analysis by IBM SPSS Statistics 25 programs. The results of this study were as follows: First, in the correlation analysis between mathematics and science achievement, it was confirmed that the Pearson's coefficient of chemistry showed higher positive correlation coefficient than that of other science subjects. Second, in the factor analysis of mathematics and science achievements, it was found that the factor indicators were divided into two factors as logical-mathematical (mathematics and physics) and naturalistic (life science and earth science). Third, in the factor analysis, it was confirmed that the chemistry is recognized as the subject that requires both logical-mathematical and naturalistic intelligence. Finally, it was confirmed that students' cognitions of chemistry subject were found to differ according to the R&E classes. In other words, the participants of R&E chemistry class, unlike other students, were found to recognize chemistry as the subject that logical-mathematical intelligence is needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.659-666
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• 2016

Magnetic disturbance is one of the main factors that deteriorate the accuracy of orientation estimation methods based on inertial/magnetic sensor signals. This paper proposes a parallel Kalman filter(KF) that explicitly detects magnetic disturbances and thus can accurately estimate 3D orientation in magnetically disturbed environments. Due to the parallel nature of the proposed KF, even severe magnetic disturbances only affect yaw estimation, while roll and pitch values remain accurate. Consequently, the proposed KF can be effectively used in various applications that involve magnetically inhomogeneous environments, such as robots, ships, and planes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.549-557
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• 2019

In this paper, we focus on the real-time detection method of a seismic ionospheric disturbance using Global Navigation Satellite System (GNSS) signal. First, the monitor for the detection of the seismic ionospheric disturbance is studied based on the estimated ionospheric delay using the GNSS signals. And then, the threshold for the automatic detection is computed. Moreover, to discriminate the seismic ionospheric disturbance against the other ionospheric anomalies due to other error sources such as cycle slips, the signatures of the ionospheric perturbation caused by the seismic wave is investigated. Based on the observation, the detection strategy is proposed. Using GPS observations collected from the 47 permanent stations in South Korea and Japan, the proposed real-time detection method is evaluated.