• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.530-534
• /
• 2006

조류발전은 조류 유속이 빠른 곳에 수차발전기를 설치하여 해수의 운동에너지로부터 전기를 생산하는 발전방식이다. 2001년부터 해양연구원에서는 울돌목의 우수한 조류발전 개발 여건을 바탕으로 조류에너지 실용화 기술을 개발하고 있다. 본 연구에서는 조류발전 시스템에 사용되는 헬리컬 수차의 효율을 현장실험을 바탕으로 판단하고자 하였다. 현장실험을 위하여 지름 2.2 m, 높이 2.5 m의 수차를 제작하고, 울돌목 협수로의 한 쪽 면에 쟈켓구조물을 설치하여 수차를 거치한다. 수차가 회전함에 따라 회전봉에 일정 마찰을 주어 토크와 RPM을 측정하고, 함께 측정된 유속자료를 이용하여 수차를 효율을 산정한다. 유속-수차효율, TSR(수차의 날개속도와 유속의 비)-수차효율의 상관관계로 실험결과를 고찰하였다. 1중 날개 수차인 경우에 유속 1.4에서 2.6 m/s 사이에서 최대효율이 30 - 35 % 정도였고, 2중 날개 수차에 대한 실험에서는 유속 1.4에서 2.6 m/s 사이에서 최대수차효율이 25 - 35 % 사이임을 알 수 있었다. TSR과 최대수차효율의 상관관계는 실험 case별로 조금씩 다르다. 전체적으로 1중 날개의 경우가 최대수차효율에서 2중 날개보다 TSR 값이 조금 큰 경향을 나타냄을 알 수 있다. 이것은 1중 날개가 2중 날개보다 가벼워 좀 더 큰 RPM을 발생시켜서 나타난 현상으로 생각된다. 현재의 실험결과들을 이용하여 TSR과 최대수차효율을 상관관계를 나타내는 모델식을 도출하였다. 현장시험결과를 종합하면, 현장조류발전 시설이 최소 600 kW의 전력이 생산되기 위해서는 지름 3 m, 높이 3.6 m 인 수차 3개가 하나의 축에 설치되어야하는 것으로 계산되었다. 정격유속이 4.8 m/s이고 수차의 지름이 3m 라면, 최적 전력발생시의 RPM은 1중 날개의 경우 79이고 2중 날개의 경우는 63정도임을 추정할 수 있었다.촬영하여 실시간으로 전송하기 때문에 홍수시 하천 상황에 대한 모니터링 목적으로 사용될 수 있다. 영상수위계는 우물통 등을 이용하는 기존 방법과 비교하여 구조물이 필요 없어 설치 비용이 저렴하고, 영상에 의한 하천 모니터링 기능을 자체적으로 가지고 있기 때문에 효율적이라고 할 수 있다.따른 4개의 평가기준과 26개의 평가속성으로 이루어진 2단계 기술가치평가 모형을 구축하였으며 2개의 개별기술에 대한 시범적용을 실행하였다.하는 것으로 추정되었다.면으로의 월류량을 산정하고 유입된 지표유량에 대해서 배수시스템에서의 흐름해석을 수행하였다. 그리고, 침수해석을 위해서는 2차원 침수해석을 위한 DEM기반 침수해석모형을 개발하였고, 건물의 영향을 고려할 수 있도록 구성하였다. 본 연구결과 지표류 유출 해석의 물리적 특성을 잘 반영하며, 도시지역의 복잡한 배수시스템 해석모형과 지표범람 모형을 통합한 모형 개발로 인해 더욱 정교한 도시지역에서의 홍수 범람 해석을 실시할 수 있을 것으로 판단된다. 본 모형의 개발로 침수상황의 시간별 진행과정을 분석함으로써 도시홍수에 대한 침수위험 지점 파악 및 주민대피지도 구축 등에 활용될 수 있을 것으로 판단된다. 있을 것으로 판단되었다.4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을 발견하였다. 이상의 행태적 측면과 투자성과측면의 실증결과를 통하여 한국주식시장에 있어서 시장수익률을 평균적으로 초과할 수 있는 거래전략은 존재하므로 이러한 전략을 개발 및 활용할 수 있으며, 특히, 한국주식시장에 적합한 거래전략은 반전거래전

• Science of Emotion and Sensibility
• /
• v.21 no.1
• /
• pp.59-70
• /
• 2018

With the breakthrough of speech recognition technology, conversational agents have become pervasive through smartphones and smart speakers. The recognition accuracy of speech recognition technology has developed to the level of human beings, but it still shows limitations on understanding the underlying meaning or intention of words, or understanding long conversation. Accordingly, the users experience various errors when interacting with the conversational agents, which may negatively affect the user experience. In addition, in the case of smart speakers with a voice as the main interface, the lack of feedback on system and transparency was reported as the main issue when the users using. Therefore, there is a strong need for research on how users can better understand the capability of the conversational agents and mitigate negative emotions in error situations. In this study, we applied social strategies, "forewarning" and "apology", to conversational agent and investigated how these strategies affect users' perceptions of the agent in breakdown situations. For the study, we created a series of demo videos of a user interacting with a conversational agent. After watching the demo videos, the participants were asked to evaluate how they liked and trusted the agent through an online survey. A total of 104 respondents were analyzed and found to be contrary to our expectation based on the literature study. The result showed that forewarning gave a negative impression to the user, especially the reliability of the agent. Also, apology in a breakdown situation did not affect the users' perceptions. In the following in-depth interviews, participants explained that they perceived the smart speaker as a machine rather than a human-like object, and for this reason, the social strategies did not work. These results show that the social strategies should be applied according to the perceptions that user has toward agents.

• Korean Journal of Remote Sensing
• /
• v.37 no.5_3
• /
• pp.1475-1490
• /
• 2021

Detecting oil spill area using statistical characteristics of SAR images has limitations in that classification algorithm is complicated and is greatly affected by outliers. To overcome these limitations, studies using neural networks to classify oil spills are recently investigated. However, the studies to evaluate whether the performance of model shows a consistent detection performance for various oil spill cases were insufficient. Therefore, in this study, two CNNs (Convolutional Neural Networks) with basic structures(Simple CNN and U-net) were used to discover whether there is a difference in detection performance according to the structure of CNN and distribution characteristics of oil spill. As a result, through the method proposed in this study, the Simple CNN with contracting path only detected oil spill with an F1 score of 86.24% and U-net, which has both contracting and expansive path showed an F1 score of 91.44%. Both models successfully detected oil spills, but detection performance of the U-net was higher than Simple CNN. Additionally, in order to compare the accuracy of models according to various oil spill cases, the cases were classified into four different categories according to the spatial distribution characteristics of the oil spill (presence of land near the oil spill area) and the clarity of border between oil and seawater. The Simple CNN had F1 score values of 85.71%, 87.43%, 86.50%, and 85.86% for each category, showing the maximum difference of 1.71%. In the case of U-net, the values for each category were 89.77%, 92.27%, 92.59%, and 92.66%, with the maximum difference of 2.90%. Such results indicate that neither model showed significant differences in detection performance by the characteristics of oil spill distribution. However, the difference in detection tendency was caused by the difference in the model structure and the oil spill distribution characteristics. In all four oil spill categories, the Simple CNN showed a tendency to overestimate the oil spill area and the U-net showed a tendency to underestimate it. These tendencies were emphasized when the border between oil and seawater was unclear.

• Economic and Environmental Geology
• /
• v.56 no.5
• /
• pp.589-601
• /
• 2023

We compare high-resolution seabed bathymetry data and seafloor backscattering data acquired, using multi-beam, between 2018 and 2021 to understand topographic changes in the coastal area of Dokdo. The study area, conducted within a 500 m × 500 m in the southern coast between the islands where Dongdo Port is located, has been greatly affected by human activities, waves and ocean currents. The depth variations exhibit between 5 - 70 m. Irregular underwater rocks are distributed in areas with a depth of 20 m or less and 30 - 40 m. As a whole, water depth ranges similar in the east-west direction and become flatter and deeper. The bathymetry contour in 2020 tends to move south as a whole compared to 2018 and 2019. The south moving of the contours in the survey area indicates that the water depth is shallower than before. Since the area where the change in the depth occurred is mainly formed of sedimentary layers, the change in the coast of Dokdo were mainly caused by the inflow of sediments, due to the influence of wind and waves caused by these typhoons (Maysak and Haishen) in 2020. In the Talus area, which developed on the shallow coast between Dongdo and Seodo, the bathymetry changed in 2020 due to erosion or sedimentation, compared to the bathymetry in 2019 and 2018. It is inferred that the changes in the seabed environment occur as the coastal area is directly affected by the typhoons. Due to the influence of the typhoons with strong southerly winds, there was a large amount of sediment inflow, and the overall tendency of the changes was to be deposited. The contours in 2021 appears to have shifted mainly northward, compared to 2020, meaning the area has eroded more than 2020. In 2020, sediments were mainly moved northward and deposited on the coast of Dokdo by the successive typhoons. On the contrary, the coast of Dokdo was eroded as these sediments moved south again in 2021. Dokdo has been largely affected by the north wind in winter, so sediments mainly move southward. But it is understood that sediments move northward when affected by strong typhoons. Such continuous coastal change monitoring and analysis results will be used as important data for longterm conservation policies in relation to topographical changes in Dokdo.

• Korean Security Journal
• /
• no.62
• /
• pp.35-63
• /
• 2020

As the frequency and intensity of catastrophic disasters increase, there is widespread public sentiment that government capacity for disaster response and recovery is fundamentally limited, and that the involvement of civil society and the private sector is ever more vital. That is, in order to strengthen national disaster response capacity, governments need to build disaster systems that are more participatory and function through the channels of civil society, rather than continuing themselves to bear sole responsibility for these "wicked problems." With the advancement of smart mobile technology and social media, government and society as a whole have been called upon to apply these new information and communication technologies to address the current shortcomings of government-led disaster management. As illustrated in such catastrophic disasters as the 2011 Tohoku earthquake and tsunami in Japan, the 2010 Haitian earthquake, and Hurricane Katrina in the United States in 2005, the realization of participatory potential of smart technologies for better disaster response has enabled citizen participation via new smart technologies during disasters and resulted in positive impact on the management of such disasters. In this context, this study focuses on the South Korean context, and aims to analyze Korean government officials' readiness for public participation using smart technologies. On this basis, it aims to offer policy suggestions aimed at promoting smart technology-enabled citizen participation. For this purpose, it proposes a particular model, termed SMART (System, Motivation, Ability, Response, and Technology).

• Progress in Medical Physics
• /
• v.26 no.4
• /
• pp.208-214
• /
• 2015

The aim of this study is to investigate the effect of low magnetic field on dose distribution in the partial-breast irradiation (PBI). Eleven patients with an invasive early-stage breast carcinoma were treated prospectively with PBI using 38.5 Gy delivered in 10 fractions using the $ViewRay^{(R)}$ system. For each of the treatment plans, dose distribution was calculated with magnetic field and without magnetic field, and the difference between dose and volume for each organ were evaluated. For planning target volume (PTV), the analysis included the point minimum ($D_{min}$), maximum, mean dose ($D_{mean}$) and volume receiving at least 90% ($V_{90%}$), 95% ($V_{95%}$) and 107% ($V_{107%}$) of the prescribed dose, respectively. For organs at risk (OARs), the ipsilateral lung was analyzed with $D_{mean}$ and the volume receiving 20 Gy ($V_{20\;Gy}$), and the contralateral lung was analyzed with only $D_{mean}$. The heart was analyzed with $D_{mean}$, $D_{max}$, and $V_{20\;Gy}$, and both inner and outer shells were analyzed with the point $D_{min}$, $D_{max}$ and $D_{mean}$, respectively. For PTV, the effect of low magnetic field on dose distribution showed a difference of up to 2% for volume change and 4 Gy for dose. In OARs analysis, the significant effect of the magnetic field was not observed. Despite small deviation values, the average difference of mean dose values showed significant difference (p<0.001), but there was no difference of point minimum dose values in both sehll structures. The largest deviation for the average difference of $D_{max}$ in the outer shell structure was $5.0{\pm}10.5Gy$ (p=0.148). The effect of low magnetic field of 0.35 T on dose deposition by a Co-60 beam was not significantly observed within the body for PBI IMRT plans. The dose deposition was only appreciable outside the body, where a dose build-up due to contaminated electrons generated in the treatment head and scattered electrons formed near the body surface.

• Journal of Korean Home Economics Education Association
• /
• v.17 no.4 s.38
• /
• pp.101-115
• /
• 2005

The purpose of this research was to develop and applicate In based teaching$\cdot$learning process plan for Environmentally friendly Housing. The 3 main stages of process were used: analyses, planning & development, and application & evaluation. Three teaching subjects were selected to teach Environmentally friendly housing in the analysis stage. The webhard learning environment was consisted of contents and various materials such as digital video, PPT, group activity, discussion, individual and group reporting forms, and questions. The number of 101 high school students participated for the application stage during september 22-27, 2003. Most of all students evaluated very positively the various aspects of contents as well as LT cooperative learning methods md the web based learning environment. They strongly expressed to practice the practical ways of Environmentally friendly housing learned in the class in the future. The results imply that the contents and In teaching learning plan developed in this study seem to be adequate to be included in the regular text.

• Geophysics and Geophysical Exploration
• /
• v.21 no.3
• /
• pp.171-182
• /
• 2018

We performed the seismic field data processing using an open-source software (Madagascar) to verify if it is applicable to processing of field data, which has low signal-to-noise ratio and high uncertainties in velocities. The Madagascar, based on Python, is usually supposed to be better in the development of processing technologies due to its capabilities of multidimensional data analysis and reproducibility. However, this open-source software has not been widely used so far for field data processing because of complicated interfaces and data structure system. To verify the effectiveness of the Madagascar software on field data, we applied it to a typical seismic data processing flow including data loading, geometry build-up, F-K filter, predictive deconvolution, velocity analysis, normal moveout correction, stack, and migration. The field data for the test were acquired in Gunsan Basin, Yellow Sea using a streamer consisting of 480 channels and 4 arrays of air-guns. The results at all processing step are compared with those processed with Landmark's ProMAX (SeisSpace R5000) which is a commercial processing software. Madagascar shows relatively high efficiencies in data IO and management as well as reproducibility. Additionally, it shows quick and exact calculations in some automated procedures such as stacking velocity analysis. There were no remarkable differences in the results after applying the signal enhancement flows of both software. For the deeper part of the substructure image, however, the commercial software shows better results than the open-source software. This is simply because the commercial software has various flows for de-multiple and provides interactive processing environments for delicate processing works compared to Madagascar. Considering that many researchers around the world are developing various data processing algorithms for Madagascar, we can expect that the open-source software such as Madagascar can be widely used for commercial-level processing with the strength of expandability, cost effectiveness and reproducibility.

• Journal of Korea Entertainment Industry Association
• /
• v.15 no.1
• /
• pp.131-142
• /
• 2021

Purpose: Clinical practicums via non-face-to-face methods were inevitable due to the COVID-19 pandemic. We developed an online program for emergency nursing care and identified the feasibility of the program and the learning achievements of students. Methods: This was a methodological study. The program was developed by three professors who taught theory and clinical practicum for adult nursing care and clinical experts. Students received four hours of video content and two task activities every week in four-week program. Real-time interactive video conferences were included. Qualitative and qualitative data were collected. Results: A total of 96 students participated in the program. The mean score for overall satisfaction with the online program was 4.72(±1.02) out of 6. Subjects that generally had high learning achievement scores were basic life support care, fall prevention, nursing documentation, infection control, and anaphylaxis care. As a result of a content analysis of 77 reflective logs on the advantages of this program, students reported that "experience in applying nursing process," "case-based learning and teaching method," and "No time and space constraints" were the program's best features. Conclusion: Collaboration between hospitals and universities for nursing is more important than ever to develop online content for effective clinical practicum.

• Korean Journal of Remote Sensing
• /
• v.40 no.1
• /
• pp.19-31
• /
• 2024

Ports are vital social infrastructures that significantly influence both people's lives and a country's economy. In South Korea, the aging of port infrastructure combined with the increased frequency of various natural disasters underscores the necessity of displacement monitoring for safety management of the port. In this study, the time-series displacements of Yeongilman Port and surrounding areas in Pohang, South Korea, were measured by applying Permanent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) to Sentinel-1 SAR images collected from the satellite's ascending (February 2017-July 2023) and descending (February 2017-December 2021) nodes, and the displacement associated with the 2017 Pohang earthquake in the port was analyzed. The southern (except the southernmost) and central parts of Yeongilman Port showed large displacements attributed to construction activities for about 10 months at the beginning of the observation period, and the coseismic displacement caused by the Pohang earthquake was up to 1.6 cm of the westward horizontal motion and 0.5 cm of subsidence. However, little coseismic displacement was observed in the southernmost part of the port, where reclamation was completed last, and in the northern part of the oldest port. This represents that the weaker the consolidation of the reclaimed soil in the port, the more vulnerable it is to earthquakes, and that if the soil is very weakly consolidated due to ongoing reclamation, it would not be significantly affected by earthquakes. Summer subsidence and winter uplift of about 1 cm have been repeatedly observed every year in the entire area of Yeongilman Port, which is attributed to volume changes in the reclaimed soil due to temperature changes. The ground of the 1st and 2nd General Industrial Complexes adjacent to Yeongilman Port subsided during the observation period, and the rate of subsidence was faster in the 1st Industrial Complex. The 1st Industrial Complex was observed to have a westward horizontal displacement of 3 mm and a subsidence of 6 mm as the coseismic displacement of the Pohang earthquake, while the 2nd Industrial Complex was analyzed to have been little affected by the earthquake. The results of this study allowed us to identify the time-series displacement characteristics of Yeongilman Port and understand the impact of earthquakes on the stability of a port built by coastal reclamation.