• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.972-976
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• 2006

비점오염은 일정한 오염원 없이 광범위한 지역에 쌓여 있는 오염물질이 강우 등에 의해 산발적으로 유출되는 비정형적인 오염을 말한다. 비점오염물질의 유출은 강우나 해빙에 의해 일시에 다량 발생되어 수계로 빠른 시간 내에 도달되게 되므로 인근 수계환경의 수질에 악영향을 미치게 되며, 이러한 오염물질을 효율적으로 처리하기 위해서는 발생원 가까이에서 수계에 도달하기 전에 저감하거나 유출과정에서 집수 처리하는 것이 가장 바람직하다. 본 연구에서는 이러한 비점오염물질의 저감을 위해 반응조를 이용한 실내실험을 실시하였다. 실내 실험장치는 아크릴로 제작 되었으며, 제원은 $1,000mm(L){\times}150mm(W){\times}300mm(H)$였다. 유입수는 시약을 이용하여 질소와 인의 농도를 고농도와 저농도로 조제하여 사용하였고, 유입은 미량 유량펌프를 이용하여 유입하였다. 토양의 오염물질의 처리 효율이 표면유출보다 하부유출에서 더 좋은 것으로 나타났기 때문에 하부유출의 양을 늘이기 위해 인위적으로 물의 흐름을 막는 정류벽을 설치한 계단형으로 구성하여 직선형과 비교하였다. 연구 결과, 단기간 저농도의 경우T-N, T-P부분에서 보면 직선형과 계단형의 표면유출 에서의 저감 효율이 T-N은 각각 -2.6 %, 2.4 %, T-P는 각각 -11.0 %, 52.9 %로 표면유출수의 오염저감효과가 개선되는 것으로 나타났다. 이는 방류벽 앞에 하부로 침투되었던 물이 표면으로 유출되면서 오염물질의 저감이 일어났기 때문으로 판단된다. 반면, 단면 및 하부유출수의 오염물질 농도는 증가한 것으로 나타났는데, 이는 토양내의 입경이 작은 silt나 clay보다 입경이 큰 모래나 자갈을 경유 하면서 오염물의 저감효과가 감소한 것으로 판단된다. 그러나 유입유량의 대부분이 표면으로 유출된다는 점을 고려할 때 표면유출수의 오염도를 낮추는 것이 유입오염물 저감효과에 보다 큰 효과가 있을 것으로 판단된다.문에 자료의 이상적 유지 관리가 이루어지며 복잡한 2차원 수질해석 모형을 수월하게 운영할 수 있는 시스템으로 개발하였다.제외하면, 부자측정 방법에 의한 유량산정시 가장 큰 오차원인은 홍수시 측정된 유속측선의 위치와 홍수 전후로 측정된 횡단면상의 위치가 일치하지 않는 점과, 대부분 두 측정 구간의 평균값을 대푯값으로 사용한다는 점이다. 본 연구는 다년간의 유량 측정 및 검증 경험과 자료를 토대로 현장에서 부자를 이용하여 측정된 측정성과를 정확도 높은 유량자료로 산정하는데 있어서의 문제점을 도출하고, 이로 인해 발생하는 오차를 추정하여 그 개선방안을 제시해 보고자한다. 더불어 보다 정확한 유량 산정을 위한 기준과 범주를 제시하고자 한다.리적 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 반전거래전략이고, 이 전략의 유용성은 투자자가 설정한 투자기간보다 더욱 긴 분석기간의 주식가격정보에 의하여 최대한 발휘될 수 있음을 확인하

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.1-8
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• 2020

In recent years, due to the exponential increase in internet data, many fields such as deep learning have developed, but side effects generated as commercial advertisements, such as viral marketing, have been discovered. This not only damages the essence of the internet for sharing high-quality information, but also causes problems that increase users' search times to acquire high-quality information. In this study, we define advertisement as "a text that obscures the essence of information transmission" and we propose a model for filtering information according to that definition. The proposed model consists of advertisement filtering and advertisement filtering performance improvement and is designed to continuously improve performance. We collected data for filtering advertisements and learned document classification using KorBERT. Experiments were conducted to verify the performance of this model. For data combining five topics, accuracy and precision were 89.2% and 84.3%, respectively. High performance was confirmed, even if atypical characteristics of advertisements are considered. This approach is expected to reduce wasted time and fatigue in searching for information, because our model effectively delivers high-quality information to users through a process of determining and filtering advertisement paragraphs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.121-128
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• 2020

The Marine Safety Culture Index (MSCI) was developed in the year 2018 for objectively assessing the public safety culture levels and for incorporating it as data to spread knowledge regarding the marine safety culture. The method for calculating the safety culture index should include issues that may affect the safety culture and should consist of appropriate attributes for estimating the current status. In addition, continuous verification and supplementation are required for addressing social and economic changes. In this study, to determine whether the questionnaire designed by marine experts reflects the people's interests and needs, we analyzed 915 marine safety proposals. Text mining was employed for analyzing the unstructured data of the marine safety proposals, and network analysis and topic modeling were subsequently performed. Analysis of the marine safety proposals was centered on attributes such as education, public relations, safety rules, awareness, skilled workers, and systems. Eighteen questions were modified and supplemented for reflecting the marine safety proposals, and reliability of the revised questions was analyzed. Furthermore, compared to the previous year, the questionnaire's internal consistency was improved upon and was rated at a high value of 0.895. It is expected that by employing the derived marine safety culture index and incorporating the improved questionnaire that reflects the requirements of marine experts and the people, the improved questionnaire will contribute to the establishment of policies for spreading knowledge regarding the marine safety culture.

• Journal of the Korean Society for information Management
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• v.36 no.4
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• pp.253-277
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• 2019

In the era of the 4th Industrial Revolution, the importance of data is intensifying, but there are many cases where it is not easy to use data due to personal information protection. Although criminal justice information is expected to have various useful values such as crime prediction and prevention, scientific investigation of criminal investigations, and rationalization of sentencing, the use of criminal justice information is currently limited as a matter of legal interpretation related to privacy protection and criminal justice information. This study proposed to convert criminal justice information into 'crime data' and use it as big data through the structuralization and categorization of criminal justice information. And when using "crime data," legal issues, value in use, considerations for data generation and use were verified by experts, and future strategic development plans were identified. Finally we found that 'crime data' seems to have solved the privacy problem, but it is necessary to specify in the criminal justice information related law and it is urgent to be organized in a standardized form for analysis to use big data. Future directions are to derive data elements, construct a dictionary thesaurus, define and classify personal sensitive information for data grading, and develop algorithms for shaping unstructured data.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.2
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• pp.95-104
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• 2017

As the technology in smart device is growing and Social Network Services(SNS) are becoming more common, the data which is difficult to be processed by existing RDBMS are increasing. As a result of this, NoSQL databases are getting popular as an alternative for processing massive and unstructured data generated in real time. The demand for the technique of digital investigation of NoSQL databases is increasing as the businesses introducing NoSQL database in their system are increasing, although the technique of digital investigation of databases has been researched centered on RDMBS. New techniques of digital forensic investigation are needed as NoSQL Database has no schema to normalize and the storage method differs depending on the type of database and operation environment. Research on document-based database of NoSQL has been done but it is not applicable as itself to other types of NoSQL Database. Therefore, the way of operation and data model, grasp of operation environment, collection and analysis of artifacts and recovery technique of deleted data in HBase which is a NoSQL column-based database are presented in this paper. Also the proposed technique of digital forensic investigation to HBase is verified by an experimental scenario.

• The Journal of Society for e-Business Studies
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• v.25 no.1
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• pp.13-33
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• 2020

This study proposes a Korean sentimental analysis algorithm that utilizes a letter-unit embedding and convolutional neural networks. Sentimental analysis is a natural language processing technique for subjective data analysis, such as a person's attitude, opinion, and propensity, as shown in the text. Recently, Korean sentimental analysis research has been steadily increased. However, it has failed to use a general-purpose sentimental dictionary and has built-up and used its own sentimental dictionary in each field. The problem with this phenomenon is that it does not conform to the characteristics of Korean. In this study, we have developed a model for analyzing emotions by producing syllable vectors based on the onset, peak, and coda, excluding morphology analysis during the emotional analysis procedure. As a result, we were able to minimize the problem of word learning and the problem of unregistered words, and the accuracy of the model was 88%. The model is less influenced by the unstructured nature of the input data and allows for polarized classification according to the context of the text. We hope that through this developed model will be easier for non-experts who wish to perform Korean sentimental analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.896-905
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• 2004

In this paper, the design, fabrication and experiment on a planar array antenna with a flat-topped radiation pattern for a mobile base station antenna were described. The current distribution of an antenna aperture, which is easily realizable in a feeding network compared with the conventional one of sin(x)/x was optimized for shaping a desired flat-topped radiation pattern. The planar array antenna designed in this paper has a rectangular lattice and is composed of array elements of 16${\times}$8. Each radiating element, which is a microstrip element fed coaxially, has a linear vertical polarization and the feed network which use a Wilkinson power divider and a 180$^{\circ}$ ring hybrid coupler as a base element is designed. The flat-topped radiation pattern with 90$^{\circ}$ is shaped by 16 array elements with the element spacing of 0.55 λ$_{ο}$ in the azimuth plane, and the normal radiation pattern with 10$^{\circ}$ is shaped by 8 array elements with the element spacing of 0.65 λ$_{ο}$ in the elevation plane. Also, the planar array antenna is symmetrically divided into four parts. It consists of one hundred-twenty-eight radiating elements, thirty-two 1-4 column dividers, low 1-8 row dividers and one 1-4 input power divider. In order to verify electrical performances of the planar way antenna proposed in this paper, the experimental breadboard operated in tile band of 1.92～2.17 GHz(IMT2000 band) was fabricated, and its experimental results were a good agreement with simulation ones.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.231-243
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• 2016

This study presents the applicability of two-dimensional (2D) flood inundation model by applying to real irrigation reservoir failure with limited available data. The study area is Sandae Reservoir placed in Gyeongju and downstream area of it and the reservoir was failured by piping in 2013. The breach hydrograph was estimated from one-dimensional (1D) hydrodynamic model and the discharge was employed for upstream boundary of 2D flood inundation model. Topography of study area was generated by integrating digital contour map and satellite data, and Cartesian grids with 3m resolution to consider geometry of building, road and public stadium were used for 2D flood inundation analysis. The model validation was carried out by comparing predictions with field survey data including reservoir breach outflow, flood extent, flood height and arrival time, and identifying rational ranges with allowed error. In addition, the applicability of 2D model is examined using different simulation conditions involving grid size, building and roughness coefficient. This study is expected to contributed to analysis of irrigation reservoirs were at risk of a failure and setting up Emergency Action Plan (EAP) against irrigation reservoir failure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.307-318
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• 2015

In this study, the efficiency of two-dimensional inundation analysis using road network was demonstrated in order to reduce the simulation time of numerical model in urban area. For this objective, three simulation conditions were set up: Case 1 considered only inundation within road zone, while Case 2 and 3 considered inundation within road and building zone together. Accordingly, Case 1 used grids generated based on road network, while Case 2 and 3 used uniform and non-uniform grids for whole study area, respectively. Three simulation conditions were applied to Samsung drainage where flood damage occurred due to storm event on Sep. 21, 2010. The efficiency of suggested method in this study was verified by comparison the accuracy and simulation time of Case 1 and those of Case 2 and 3. The results presented that the simulation time was fast in the order of Case 1, 2 and 3, and the fit of inundation area between each case was more than 85% within road zone. Additionally, inundation area of building zone estimated from inundation rating index gave a similar agreement under each case. As a result, it is helpful for study on real-time inundation forecast warning to use a proposed method based on road network and inundation rating index for building zone.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.552-561
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• 2016

In this experimental study, the dynamic stability derivatives of a tailless lambda-shape UAV are estimated from time history data of aerodynamic moments measured from the internal balance while the test model is forced to oscillate at given frequencies and amplitudes. A 3-axis forced oscillation apparatus is designed to induce decoupled roll, yaw, pitch oscillations respectively. The results show that the roll damping derivatives remain stable at the entire range of angle of attack tested, whereas the pitch damping derivatives become unstable beyond $15^{\circ}$ angle of attack. The amplitude and frequency have little impact on roll damping derivatives while the smaller amplitude and frequency of oscillation improves the pitch stability. The yaw damping derivative values are fairly small as expected for a tailless configuration. The results indicate that the proposed methodology and test apparatus area valid for estimating the dynamic stability derivatives of a tailless UAV.