• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.445-445
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• 2022

최근 새만금 방조제 건설이 완료됨에 따라 주변 연안지역의 지형에 많은 변화가 감지되었다. 본 연구대상지는 격포해수욕장으로서 새만금 사업 준공 후 연안침식에 따른 모래 유실 등으로 인해 양빈사업 등이 검토되고 있는 상황이다. 본 연구에서는 연안지형 변화 탐지를 위한 UAV (Unmanned Aerial Vehicle) 활용기술을 제시하는 것으로서 총 3회에 걸쳐 UAV 영상을 촬영하였다. 영상촬영은 DJI Inspire 2 UAV를 활용하였으며 VRS(Virtual Reference Service) 측량성과와 연계하여 Pix4D Mapper SW를 통해 정사영상과 수치표면모델(DSM; Digital Surface Model)을 제작하였다. 먼저 2018. 6. 29 ~ 2018. 12. 10 사이의 지형변화 탐지를 수행한 결과 침식과 퇴적의 최대값은 각각 2.56m와 2.24m로 나타났으며 평균적으로는 0.01m의 퇴적이 발생하였다. 그리고 2018. 6. 29 ~ 2019. 6. 14 동안의 침식과 퇴적의 최대값은 각각 2.31m와 2.28m로 나타났으며 평균값은 0.02m의 침식이 발생하였다. 또한 2018. 12. 10 ~ 2019. 6. 14 사이에는 침식과 퇴적의 최대값이 각각 2.28m와 2.55m로 나타났으며 평균값은 0.03m의 침식이 발생하였다. 지형변화를 보다 상세히 모니터링하고자 퇴적과 침식구간을 나누어 분석을 수행한 결과, 2018. 6. 29 ~ 2018. 12. 10 사이에는 0.5m 이내의 침식과 퇴적구간 면적이 각각 13,324.4m²와 14,667.3m²로 퇴적구간의 면적이 1,342.9m² 만큼 높게 나타났으며, 2018. 12. 10 ~ 2019. 6. 14 사이에는 0.5m 이내의 침식과 퇴적구간 면적이 각각 16,176.6m²와 11,723.0m²로 침식구간의 면적이 4,453m² 만큼 높게 나타났다. 또한 2018. 12. 10 ~ 2019. 6. 14 사이에는 0.5m 이내의 침식과 퇴적구간 면적이 각각 16,821.6m²와 11,126.4m²로 침식구간의 면적이 5,695.2m² 만큼 크게 분석되었다. 이와 같이 UAV 영상 기반의 연안지형 모니터링을 수행할 경우 시계열 지형변화를 효과적으로 모니터링할 수 있으며, 이러한 업무는 새만금 방조제 건설에 따른 지형변화의 영향평가 등 다양한 연안업무에 활용될 수 있을 것이다.

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.23-30
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• 1999

Pregnant ICR mice were treated with 137Cs gamma-ray / ultrasound on day 8 of gestation. In combined treatments, pregnant mice were treated with both 1.5 Gy of radiation and $1.0W/cm^2$ ultrasound at time intervals of -1, 0, 1, 3 and 6 hours. The mortalities and external malformations were investigated on day 18 of gestation. The threshold dose of mortality induced by radiation on day 8 of gestation was between 0.5 and 1.0 Gy, and that which was induced by ultrasound was between 1.0 and $1.5W/cm^2$. The mortalities in the late-stage of gestation induced by combined treatment with radiation and ultrasound increased synergistically. The threshold dose of exencephaly and anophthalmia induced by radiation were between 0.5 and 1.0 Gy and between 1.0 and 1.5 Gy, respectively. Those of exencephaly and anophthalmia induced by ultrasound were between 1.0 and $1.5W/cm^2$ and more than $1.5W/cm^2$, respectively. In combined treatments, the incidence of exencephaly and anophthalmia were found to increase synergistically. In the mice treated with both agents at a time interval of one hour, the incidence of exencephaly and anophthalmia reached maximum levels.

• Food Science of Animal Resources
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• v.24 no.4
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• pp.386-392
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• 2004

The objective of this experiment was to compare tile effect of feeding the commercial feeds (control) or fermented food waste feeds (FEWF) on consumer's acceptability and preference of pork belly. The bellies from carcasses of gilts and barrows were used. The consumers evaluated raw meat for color, freshness, fat amount (5=too much fat; 1= not enough fat), fat acceptability and overall acceptability on 5-point stale (5=most desirable; 3=moderate; 1=least desirable) and grilled belly for flavor, taste, texture, juiciness and overall acceptability on 5-point scale (5=most desirable; 3=moderate: 1=least desirable). Raw belly of control had higher scores in color than belly fed FFWF. However, there were no differences between treatments for freshness, fat contents, acceptability of fat contents and overall acceptability (p>0.05). There were no differences in any sensory trait between control and FFWF belly after cooking (p>0.05). Mean scores for preference or overall-liking of raw and cooked belly also were not significantly different between two groups (p>0.05). This results mean that feeding FFWF to pork didn't change the sensory Properties of belly meat.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.61-67
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• 2018

This study was conducted to ascertain the mediating effects of aggression in high school students' relationship with smartphone overuse and cyberbullying. Data were collected from 328 high school students in K city using self-report questionnaire. The collected data were analyzed using SPSS 22.0 and AMOS 22.0. The results show that cyberbullying has a positive correlation with smatrphone overuse(r=.321, p<.001) and aggression(r=.397, p<.001). Smartphone overuse had a direct effect on aggression(${\beta}=.195$, p=.014) and aggression had a direct effect on cyberbullying(${\beta}=.260$, p=.007). In addition, the mediation effects of aggression on the relationship between smartphone overuse and cyberbullying were confirmed(${\beta}=.051$, p=.007). In order to reduce cyberbullying in high school students, it will be necessary to develop cyber ethical awareness education programs to reduce aggression as well as regulations on excessive use of smartphones.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.5-16
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• 2014

Soil-nailing has two main resistance factors: skin friction between ground and grouting; and tension load of reinforced material. These two factors will affect the load-displacement curve when performing soil-nailing pullout tests. The purpose of this paper is to figure out the shear behavior between ground and soil-nailing focusing on the net load-displacement behavior during soil-nailing pullout tests. Firstly, the net load-displacement curve between ground and grouting is estimated theoretically. Then, in-situ pullout load tests are performed on various ground conditions to obtain the load-displacement curve occuring between ground and grouting. Since the measured shear displacement includes elongation of the reinforced material (steel nails), the net load-displacement curve can be obtained by subtracting the elongation magnitude of steels from the measured displacement. It was found that the measured net load-displacement curve matches reasonably well with the theoretically estimated curve.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.77-82
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• 2013

A cyclone separator has been widely used in various industrial processes for removing fine particulate matter because it is easy to fabricate, cost effective, and adaptable to extremely harsh conditions. However, owing to the complex flow field in cyclones, a complete understanding of the detailed mechanisms of particulate removal has not yet been gained. In this study, a theoretical analysis was performed for calculating the collection efficiency and cut-off size in cyclones by taking into account the effects of geometrical and flow parameters. The collection efficiency and cut-off size values predicted by the theoretical model showed good agreement with experimental measurements for particles with a diameter of $0.5-30{\mu}m$. It was also revealed that the surface friction, along with the flow and geometrical parameters, has a significant effect on the cyclone performance.

• Korean Journal of Ichthyology
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• v.18 no.4
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• pp.329-338
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• 2006

Phylogenetic relationships and DNA polymorphism among local populations of the Korean native catfish species, Liobagrus mediadiposalis, have been investigated based on mitochondrial cytochrome b DNA sequences. As a result, three genetically distinct groups of local populations were recognized based on the phylogenetic tree constructed. The first group was called "Nakdong-river group" that included the local populations from Geumho-river, Gyeongho-river, and Deokcheon-river; the second one was "Geum-river group"; the third one was represented as "Seomjin-river group" that included the samples from Seomjin-river, Dongjin-river and Geokum-do. The phylogeny also implied that the ancestral group of L. mediadiposalis have first evolved to Nakdong-river group, and later two local populations (Geum-river and Seomjinriver group) were diverged from the other lineage. DNA polymorphisms we observed were 4.4~4.7% between Geum-river group and Seomjin-river group, 5.1~5.5% between Seomjinriver group and Nakdong-river group, and 5.5~5.7% between Nakdong-river group and Geumriver group. These results indicated the long period of geographic isolation due to the river system in Korea caused such high degrees of DNA polymorphisms between local populations of L. mediadiposalis.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.88.2-88.2
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• 2015

지난 2009-2010년 수행한 제 1차 수도권 밤하늘 밝기 측정에 이어, 우리는 2014년 12월부터 2015년 2월까지 제 2차 수도권 밤하늘 밝기 측정을 수행하였다. 이번 2차 측정에서는 지난 1차 측정과 가능한 한 동일한 장소와 조건에서 밤하늘 밝기를 측정함으로써, 지난 5년간 발생한 밤하늘 밝기 및 주변 환경의 변화와 이 둘 사이의 상관관계를 알아보고자 하였다. 밤하늘 밝기 측정에 사용된 기기는 1차 측정과 마찬가지로 'SQM(Sky Quality Meter)-L'을 사용하였다. SQM-L은 표면등급($mag/arcsec^2$) 단위로 밤하늘을 측정하며 측정 오차는 ${\pm}0.1$ 등급이다. 이번 측정 결과 밤하늘 밝기가 가장 어두운 지역은 경기도 가평군 청평면 고성리(20.6 등급)로, 1차 측정에서의 가장 어두운 지역과 동일했다. 반면 가장 밝은 지역은 서울 영등포구 윤중초교와 서울 중구 남산초교(16.5 등급)로 나타났으며, 가장 어두운 지역과 밝은 지역 사이의 밤하늘 밝기 차이는 약 40배(~4 등급)로 나타났다. 이번에 측정한 밤하늘 밝기는 지난 1차 관측에 비해 전 지역에서 평균 0.5 등급 어두워진 것으로 나타났다. 특히 서울 은평구 갈현초교는 5년 사이에 1.5 등급 어두지면서 가장 큰 차이를 보였다(1차: 16.0 등급, 2차: 17.5 등급). 본 포스터에서는 이번 측정 결과와 진행 과정을 소개하고 두 관측 기간 사이에 발생한 밤하늘 밝기 변화의 원인에 대하여 토론하고자 한다.

• Information and Communications Magazine
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• v.33 no.5
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• pp.39-46
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• 2016

디지털 사이니지(Digital Signage)는 불특정 다수에게 일대다 형태로 정보를 제공하는 디지털 정보 디스플레이(Digital Information Display)에서 사용자의 상황을 인지하여 개인 맞춤형 콘텐츠를 제공하는 상황인지기반 텔레스크린(TeleScreen)으로 진화했으며, 앞으로의 디지털 사이니지는 옥내외에 위치한 다양한 형태의 사이니지들이 주변 환경과 사용자 상황에 따라 서로 협업하여 서비스를 제공하는 오픈스크린 서비스로 발전할 전망이다. 본 고에서는 오픈스크린(Open-Screen) 서비스의 등장 배경과 개념을 소개하고 하고 본 연구원에서 개발한 오픈스크린 서비스 플랫폼 기술을 소개한다.

• Journal of the Korean Wood Science and Technology
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• v.20 no.1
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• pp.72-78
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• 1992

지진과 관련있는 하중 속도에서 damping을 측정하기 위하여 합판과 목재 사이에 한개의 못을 사용한 접합에 대하여 조사 했다. 조사된 하중은 sine function 의 15Hz와 ASTM하중 속도 사이에서 행했다. Damping 율은 4Hz까지의 하중 속도에서는 증가를 보였으며 그후 15Hz 까지는 점진적으로 감소하였다. 강성은 높은 하중 범위에서 slip moduli가 지속적으로 증가 하였다. 낮은 하중 범위에서 2.5Hz까지 증가 하였으며 그후는 감소 하였다. Damping 율과 slip modulus는 하중 속도와 상관 관계가 낮은 반면 work capacity와 dissipated energy는 높은 상관 관계를 보았다.