• Water for future
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• v.27 no.3
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• pp.55-69
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• 1994

In order to enhance the short-term flood forecasting accuracy of the water level of the In-do Brdg., three statistical flood forecasting models are presented models are presented and the forecasting accuracies and stabilities of the models are studied. The presented statistical models are as follows: The multi-input model by the multi-regression analysis between the water level of the In-do Brdg. and the influence parameters(Model MM). The two-level multi parameter model according to the water level tendency(Model 2MP). Among the three models, the Model MM showed the lowest forecasting accuracy, the model 2MP showed the highest forecasting accuracy, although this model sometimes became unstable and diverged. The model MMP forecasted the flood less accurately than model 2MP, but it gave more stable forecasting results.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.143-143
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• 2023

최근 대청댐('17), 평림댐('19) 등 광역 취수원에서 망간의 먹는 물 수질기준(0.05mg/L 이하) 초과 사례가 발생되어, 다수의 민원이 제기되는 등 취수원의 망간 관리 중요성이 부각되고 있다. 특히, 동절기 전도(Turn-over)시기에 고농도 망간이 발생되는 경우가 많은데, 현재 정수장에서는 망간을 처리하기 위해 유입구간에 필터를 설치하고 주기적으로 교체하는 방식으로 처리하고 있다. 그러나 단기간에 고농도 망간 다량 유입 시 처리용량의 한계 등 정수장에서의 공정관리가 어려워지므로 사전 예측에 의한 대응 체계 고도화가 필요한 실정이다. 본 연구는 광역취수원인 주암댐을 대상으로 망간 예측의 정확도 향상 및 예측기간 확대를 위해 다양한 머신러닝 기법들을 적용하여 비교 분석하였으며, 독립변수 및 초매개변수 최적화를 진행하여 모형의 정확도를 개선하였다. 머신러닝 모형은 수심별 탁도, 저수위, pH, 수온, 전기전도도, DO, 클로로필-a, 기상, 수문 자료 등의 독립변수와 화순정수장에 유입된 망간 농도를 종속변수로 각 변수에 해당하는 실측치를 학습데이터로 사용하였다. 그리고 데이터기반 모형의 정확도를 개선하기 위해서 성층의 수준을 판별하는 지표로서 PEA(Potential Energy Anomaly)를 도입하여 데이터 분석에 활용하고자 하였다. 분석 결과, 망간 유입률은 계절 주기에 따라 농도가 달라지는 것을 확인하였고 동절기 전도시점과 하절기 장마기간 난류생성 시기에 저층의 고농도 망간이 유입이 되는 것을 분석하였다. 또한, 두 시기의 망간 농도의 변화 패턴이 상이하므로 예측 모델은 각 계절별로 구축해 학습을 진행함으로써 예측의 정확도를 향상할 수 있었다. 다양한 머신러닝 모델을 구축하여 성능 비교를 진행한 결과, 동절기에는 Gradient Boosting Machine, 하절기에는 eXtreme Gradient Boosting의 기법이 우수하여 추론 모델로 활용하고자 하였다. 선정 모델을 통한 단기 수질예측 결과, 전도현상 발생 시기에 대한 추종 및 예측력이 기존의 데이터 모형만 적용했을 경우대비 약 15% 이상 예측 효율이 향상된 것으로 나타났다. 본 연구는 머신러닝 모델을 활용한 망간 농도 예측으로 정수장의 신속한 대응 체계 마련을 지원하고, 수처리 공정의 효율성을 높이는 데 기여할 것으로 기대되며, 후속 연구로 과거 시계열 자료 활용 및 물리모형과의 연결 등을 통해 모델의 신뢰성을 제고 할 계획이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.364-364
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• 2022

최근 기후변화에 따른 잦은 이상 가뭄으로 물 부족 현상이 심화되고 있어 물 안보가 중요한 사회적 이슈로 부각되고 있다. 물 부족에 대비하기 위해 수자원은 인류가 마음대로 사용할 수 있는 자유재가 아니라 보호·관리하여야 하는 대상으로, 보유한 미사용량을 회수·재배분하여 물 이용의 공정성을 강화 등 물 이용 제도의 전반에 대한 검토·개선이 필요한 실정이다. 하지만 일부 유역에서는 하천수 사용량이 정확하게 계측되지 않아 공정한 하천수 배분 등에 한계가 발생하고 있다. 본 연구에서는 충주댐 하류 유역에 위치한 자동유량측정소 원주시(남한강대교)와 여주시(남한강교) 상·하류 유량자료를 검토·분석하여 하천수 사용허가권에 등재된 하천수 이용량을 검토하고자 한다. 아울러 상·하류 자동유량관측소 내 지류 하천(섬강, 청미천)이 유입되고 있어, 추가 유입량을 고려한 물수지 분석을 위해 원주시(문막교)수위관측소, 여주시(원부교)수위관측소의 유량자료를 이용하였다. 상·하류 유량자료 검토 결과, 지류 유입량 + 하류 여주시(남한강교)) 유량이 상류 원주시(남한강대교) 유량보다 작은 상·하류 유량이 역전('19~'20, 평균 787,753m³/day)되는 흐름이 발생하였다. 구간 내 등재된 취수시설물(11개소) 허가량(39.66×10⁶m³) 보다 실재 사용량은 많을 것으로 추정되며 상·하류 역전 흐름에 직접적인 영향을 준 것으로 판단된다, 또한 현장 조사에서 허가대장에 미등재된 다수의 시설을 발견하였으며 이는 하천수의 효율적인 관리에 장애요인으로 작용된다. 하천수 사용은 복합허가사항으로 홍수통제소에서 사용허가부터 관리까지 실시하고 있는데 하천수 허가 신청량은 계획수요량 산정과 물수지 분석결과를 통하여 적정성 검토가 이루어지고 있다. 그러나 하천수 사용허가량 대비 실제 하천수 취수량이 얼마나 되는지 파악은 불가능한 실정이다. 결국 하천 유량을 관리하기 위해 강수량, 수위, 유량 등 많은 수문요소를 정확하게 측정하는 것도 필요하지만 이처럼 하천수 이용을 위해 취수되는 양을 정확하게 계측하지 않는다면 효율적인 하천수 관리는 어렵다. 하천수를 관리하고 효율적으로 이용하기 위해 하천수 이용에 대한 제도적인 보완이 필요해 보인다.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.359-366
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• 2002

Nowadays, the hacking techniques are developed increasingly with wide use of internet. The recent type of scanning attack is appeared in against with multiple target systems on the large scaled domain rather than single network of an organization. The development of scan detection management system which can detect and analyze scan activities is necessary to prevent effectively those attacking at the central system. The scan detection management system is useful for effective utilization of various detection information that received from scan detection agents. Real time scan detection management system that can do the integrated analysis of high lever more that having suitable construction in environment of large scale network is developed.

• Journal of the Korean association of regional geographers
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• v.20 no.2
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• pp.217-229
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• 2014

This study was performed to identify neighborhood deprivation indicators associated with health and to test the contextual effects of those indicators on individual health. This study calculated SMR based on Dong district and see the differences of prediction across deprivation index and indicators. Then, a multi-level analysis using HGLM was conducted to test the contextual effect of neighborhood depreivation indicators on health after controlling for demographic and socioeconomic status of individuals. The results showed that regional SMR had strong correlations with land price, education, welfare recipients, female household proportion in Dong district but failed to show the correlation with individual health and neighborhood deprivation. Individual health was only associated with individual level of demographic and socioeconomic status. That is, spatial dispersion of illness is understood as the distribution of social classes in terms of socioeconomic status of individuals, not the contextual aspects of community.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3625-3634
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• 2014

This study was conducted to provide the basic data for the prevention and management of health risk of dental technicians by proposing the necessary data in the management of the health related quality of life of dental technicians. The subjects of the survey were 141 dental technicians working in 30 dental technical laboratories and corresponding companies in Daejeon area. A structured self-entry type questionnaire survey was implemented by measuring the work environment from December 20, 2011 to January 31, 2012 at the same time. The total score of health index showed a significant difference according to the working hours and smoking state as the a factor of the individual level, the physical health index showed a significant difference according to the smoking state and the exercise habits as the factor of the individual level. The mental health index showed a significant difference according to the working hours and smoking state as the factor of the individual level. The significant variable did not appear in the predictor of the group level. In conclusion, the quality of life of dental technicians in relation to health appeared to have a larger effect on the factor of the individual level than the factor of the group level.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.647-656
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• 2008

In this paper, we present interference power distribution results when radio frequency identification(RFID) and ubiquitous sensor network(USN) systems share the $908.5{\sim}914MHz$ frequency bands. Average interference powers are obtained by simulation and statistical analysis, respectively. Simulation results are then verified by statistical analysis. According to the number of interferers and the diameter of the protection area, the cumulative density functions(CDFs) of interference power are simulated under the various conditions. From the simulation results, the probability that both USN and RFID systems meet the required maximal interference power levels is 95 % on condition that there are 1 low revered RFID reader and several USN nodes and that the minimum distance between a RFID reader and an USN node is greater than 1 m. Our results can be used as an basic research for coexistence analysis of RFID and USN systems in the $908.5{\sim}914MHz$ frequency bands.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1502-1509
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• 2006

In this paper, we proposed reliability and capacity enhancement methods for IEEE 802.15.3 HDR-WPAN (High Data Rate-Wireless Personal Area Network) system which is currently getting an interest in home network technology adopting a MIMO technique. We also analyzed performance or the proposed system through a computer simulation. The HDR-WPAN system using V-BLAST algorithm, transmitting the different signal vector to each other's sub-channel, can get the transmission speed of more than 110Mbps using two Tx/Px antenna without bandwidth expansion in TCM-64QAM mode. Also the proposed system has reliability of 104 at $E_b/N_0=35dB$ under the Rayleigh fading channel in case of two Tx/Rx antenna with MMSE algorithm. The HDR-WPAN system adopting V-BLAST method has its drawback which is very complicated to determine the decision-ordering at the receiver. But, the proposed system enhances the transmission capacity and reliability without extra bandwidth expansion by sending data streams to multiple antennas.

• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.560-575
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• 2020

This study analyzed the actual impact of central and local governments' startup mentoring programs on the entrepreneurship and early startup business performances of company owners and prospective owners. To analyze the participants' hidden intentions, literature review, in-depth interview, and focus group interview research methodologies were used consecutively. The following results were obtained. First, participants with higher expectations toward the mentoring programs tended to evaluate the programs more negatively, with a substantial number of interviewees responding that the quality of the programs was subpar. Second, startup mentoring programs seem to have had positive effects on building entrepreneurship. The effect was especially significant in areas such as creativeness and innovation. Third, the mentoring programs did not have a significant impact on business performance, suggesting the need for institutions' active participation in mentor-mentee relations and programs. Fourth, most participants evaluated mentoring programs as unsatisfactory, meaning that the programs do not meet the intention and purpose of the institutions providing them. Based on these analyses, the academic importance of this study was highlighted and ways startup mentoring programs can improve in the future were suggested.

• The Journal of the Korea Contents Association
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• v.15 no.10
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• pp.425-435
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• 2015

While managerial coaching has increased popularly as an effective leadership initiative in organization, the relationship between managerial coaching and its effects on performance has not been scholarly well defined. This study examined the role of managerial coaching as a moderator between job characteristics and job performance. Based on the sample of 453 employees in a financial firm, HLM was conducted to test the research model at multiple levels of organizational hierarchies. First, we found that managerial coaching has a direct impact on employee performance. Second, the strength of the relationship between job meaningfulness and job performance is positively related to the level of managerial coaching. Third, managerial coaching positively moderates the association between autonomy and job performance. However, any cross-level moderating effects of managerial coaching on the relationship between feedback and job performance is not observed. These results show that managerial coaching by managers could promote employees' performance through maximizing the impact of job characteristics on employees' motivation.