• Proceedings of the Korea Information Processing Society Conference
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• 2021.05a
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• pp.297-300
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• 2021

대부분의 기업에서는 우수한 인적 자원의 유출을 방지하기 위해 직원들이 이직 및 퇴사하는 이유를 연구한다. 이에 기업은 직원이 퇴사하기 전에 면담을 하거나 설문조사를 통해서 연구에 필요한 데이터를 얻는다. 하지만 설문조사에서는 직원들이 직장 생활을 하는 데에 불리할 수도 있는 의견을 드러내려고 하지 않아 정확한 결과를 얻기 힘든 것이 현실이다. 한편, 한국노동연구원에서 발표한 자료에 따르면 기업이 요구하는 최소 학력 수준과 직원의 학력 수준 간의 차이가 클수록 이직 경향이 커진다. 따라서 본 연구에서는 한국노동연구원의 자료에 착안하여, 직원이 가지고 있는 객관적 데이터인 전공, 교육수준, 재직 중인 회사 유형 등의 데이터를 기반으로 직원의 퇴사 여부를 예측하고자 한다. 퇴사 예측 모델을 생성하기 위해 Decision Tree, XGBoost, kNN, SVM을 활용하였으며 각각의 성능을 비교했다. 이 결과, 지금까지 설문조사로 진행되었던 연구에서 파악하지 못한 다양한 요인을 알아낼 수 있었다. 이를 통해 기업이 퇴사 예측 모델을 이용하여 직원이 퇴사하기 전에 미리 이를 인지하고 방지하는 데에 도움을 줄 수 있을 것으로 예상된다.

• The Journal of Korean Association of Computer Education
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• v.20 no.1
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• pp.87-97
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• 2017

Recently, much research has been done on the turnover and retirement intentions of the organization members as many companies recognize the negative impact of the human resource outflow on the organization. However, most of the studies are conducted in the form of questionnaires, and there is still a lack of studies on the turnover and retirement intentions based on the work life data. In this study, we analyzed the factors affecting the retirement of employees based on the work life profile, and created a retirement prediction model using the machine learning method. As a result, we could identify various factors that were not covered in previous researches. In addition, we have established a basis for research that can provide a solution for the problem of human resource outflow by generating a good performance retirement prediction model.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.597-606
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• 2019

Due to climate change, coastal areas are being flooded with torrential rain, typhoons, and tsunamis. In addition, non-point source pollutants (NPSs) that accumulated on the ground, streets, and buildings during the dry season are washed off by rain and stormwater runoff, which adds to the damage associated with environmental pollution, e.g., pollution that makes its way into the ocean. Recently, low impact development (LID) has been considered as a means of controlling water circulation and NPSs. In the coastal area, permeable blocks have been constructed mainly to reduce the flood damage caused by waves. Some important design factors that must be considered to ensure long-term performance are the permeability coefficient, clogging, and the efficiency of the removal of total suspended solids (TSS), but currently there are no standardized design criteria or testing techniques that are used worldwide. Herein, we analyzed the permeability coefficient and the TSS removal efficiency tendency according to the permeability area ratio with an easily-detachable, permeable block filled with calcinated yellow soils as the filter media. Our lab-scale tests indicated that, when the permeability area ratio was 25%, the reduction of the permeability coefficient after clogged was 11%, which was a significant decrease compared to other cases. Permeability persistence increased when the permeability area ratio increased from 50% to 75%. The TSS removal efficiency decreased as the permeability area ratio increased. Our pilot-scale test indicated that the TSS removal efficiency was more than 80% higher in all cases. We also found that the permeability persistence was excellent as the permeability area ratio increased, and, in actual construction, it is effective to set 5.3% of the total area as permeable area in terms of permeability and economic feasibility.

• Journal of the Korea Computer Industry Society
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• v.8 no.4
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• pp.253-262
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• 2007

As the internet environment is applied in the various service field, the recognition on security is increasing. Because the authentication methods for web service user do not confirm person oneself, the serious problems of reliability, safety and security can be caused. In order to solve this problems, the authentication methods of user id and password or authentication key is used. Because the password and authentication key using the existent authentication methods for security is composed of a string, authentication information can easily hacked or leaked by hackers, and the serious problems of security can be caused. In this paper, in order to improve the web security, an authentication module using the fingerprint that have the unique properties of person is proposed. As the proposed module makes use of fingerprint authentication, the security of the web service user from hackers can be maintained. The proposed method is more excellent than the existent method in the web security.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.953-957
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• 2008

일반적으로 하천은 오랫동안 장기간의 변화를 겪으며 안정되어 있다. 산사태나 홍수 등 자연적인 변화뿐 아니라 댐이나 교량 등 인위적인 변화에 따라 흐름이나 유사량이 변하게 되며 이런 동적변형상태를 복원하는 과정에서 침식과 퇴적이 반복적으로 이루어져 대규모 하상변동이 이루어지게 된다. 이러한 하천에서 발생하는 대규모의 하상변동에는 일반적으로 1차원 해석이 적용된다. 하천의 일정 하도구간을 고려할 경우 구간의 상류단면으로부터 유입하는 유입토사량과 하류단면에서 유출되는 유출토사량과의 비에 따라 그 구간에는 하상상승(aggradation)및 하상저하(degradation)가 발생하게 되고 이것이 거시적 측면에서 하상변동이라 할 수 있다. 이러한 장기하상변동은 경우에 따라서 이수용도의 수문 혹은 취수구가 노출되거나, 교량의 교각에 국부세굴이 발생되어 붕괴위험이 생기는 등 심각한 문제가 발생할 수가 있다. 본 연구에서는 하상변동 예측 모형 중 신뢰성 및 적용성이 우수한 것으로 인식되고 있는 HEC-6 모형을 형산강수계에 적용하여 4가지 협착부 개선방안에 따른 장기하상변동에의 영향을 검토하고자 하였다. 하천기본계획상의 횡단면도와 유사량 실측값을 이용하여 유사모의 결과를 검증하고 2020년까지의 모형의 계산 값을 이용하여 4가지 대안에 따른 모의 결과와 원안의 결과와 비교 및 분석하였다. 모의한 결과 형산강의 하상변동치가 크지 않은 것은 형산강의 하상이 어느 정도 안정되어 있어 장기적인 하상변동이 크지 않기 때문이다. 따라서 협착부 개선에 따른 대안 1, 2, 3, 4의 하상이 크게 변하지 않음을 보였다. 지형 변화에 따른 장기하상변동에의 영향이 크지 않은 것을 확인할 수 있다.

• Journal of the Korean Institute of Gas
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• v.6 no.4 s.18
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• pp.33-39
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• 2002

[ $9\%$ ] nickel steel LNG storage tank have double containments that can store cryogenic LNG independently. Inner tank material is used as $9\%$ nickel steel and outer tank is constructed by concrete. Comer protection which is installed on inner surface of concrete corner is consist of $9\%$ nickel steel liner and form glass insulator that make reduce tension at corner when LNG is leaked from inner tank. It is very difficult to design corner protection because expansion and contraction of liner make stress state complex. Corner protections of operating tank in KOGAS are designed by Japanese engineering company such as TKK, KHI and England company of WHESSOE. This paper is mainly focused on the integrity comparison of them according to requirements of Appendix 4 in ASME Section VIII Div. 2 by using FEM.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.569-575
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• 2014

Since 2009 the number of users of smart phones and tablet PC is growing exponentially. In particular Apple's iOS and Google's Android OS are the heart of this remarkable growth, most of smart phone and tablet PC are designed to operate based on these two OS. Such increasing use of smart devices has led to changes in the social environment that allows, without the constraints of time and place. However, such development does not supply only ease to do something, even compared to past, financial fraud and information leakage are easier than before by variety of new types of attack for example phishing, pharming, smishing and qshing. So according to this paper, analyzes for smishing attack, propose a countermeasure system of the technical way and proved its higher performance compare to the existing method.

• Water for future
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• v.28 no.4
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• pp.155-169
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• 1995

Three types of methods are used to determine the lag time which is an important parameter in estimating the geomorphological instantaneous unit hydrograph (GIUH) and their results are anlyzed hydrologically in this study. The first method uses only the average velocity and second one uses the combination of the stream length and the average velocity. The third method employs the relationship between watershed area and lag time obtained from the empirical coefficients of Boyd and Singh. To verify the applicabilities of such methods to the actual river basin, the obtained lag times were tested by using the observed data. The results showed that the first method was applicable to small watershed area but not to larger area. The several other hydrologic characteristics beside the watershed area should be considered for the third method because the accuracy of the lag time was not good. Finally, the second method gave the most similar simulation results and the best agreements to the observed runoff data than any other method.

• Journal of Korea Water Resources Association
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• v.33 no.1
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• pp.123-132
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• 2000

In the study the instantaneous unit hydrographs (IUHs) based on the linear Nash (1957) and the nonlinear Diskin (1964) models are derived and compared for the Soyang river basin. Total 14 rainfall runoff events are used for the study and the model parameters are estimated by minimizing the sum of square error considering runoff hydrograph ordinates as relative weights. The representative IUHs for both models are decided to show an average shape of derived IUHs. In the application of the representative IUHs of Nash and Diskin, Diskin model shows better performances in reproducing the observed outflows, especially the peak flow. In the comparison of two Diskin models little difference could be found between the IUHs with the same or different number of two characteristic reservoirs.rvoirs.

• Journal of Korea Water Resources Association
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• v.37 no.1
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• pp.67-75
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• 2004

In this study, real-time forecasting model(Neural Dam Inflow Forecasting Model; NDIFM) based on neural network to predict the dam inflow which is occurred by flood runoff is developed and applied to check its availability for the operation of multi-purpose reservoir Developed model Is applied to predict the flood Inflow on dam Nam-Gang in Nak-dong river basin where the rate of flood control dependent on reservoir operation is high. The input data for this model are average rainfall data composed of mean areal rainfall of upstream basin from dam location, observed inflow data, and predicted inflow data. As a result of the simulation for flood inflow forecasting, it is found that NDIFM-I is the best predictive model for real-time operation. In addition, the results of forecasting used on NDIFM-II and NDIFM-III are not bad and these models showed wide range of applicability for real-time forecasting. Consequently, if the quality of observed hydrological data is improved, it is expected that the neural network model which is black-box model can be utilized for real-time flood forecasting rather than conceptual models of which physical parameter is complex.