• 디지털융복합연구
• /
• 제10권8호
• /
• pp.341-346
• /
• 2012

본 연구에서는 이러닝 환경에서의 학습참여도에 플로우 경험과 인터넷 중독이 미치는 영향을 고찰하였다. 학습참여도는 이러닝 웹 로그 분석을 통해 학습컨텐츠 접속횟수, 접속시간 및 지연시간(컨텐츠 업로드 시간과 접속시간의 시차)을 산정하여 활용하였으며, 이러한 학습참여 변인과 학업성취도간의 관계 또한 분석되었다. 연구결과, 플로우 경험은 모든 이러닝 참여 관련변인과 유의한 관계가 있는 것으로 나타났으며, 인터넷 중독은 지연시간과 유의한 관계가 있는 것으로 파악되었다. 그리고 여학생은 남학생에 비해 더 자주, 더 오래 학습컨텐츠에 접속한 것으로 나타났다. 이러닝 참여 변인 중에서는 접속횟수와 지연시간이 학업성취도에 유의한 영향을 미치는 것으로 파악되었다.

• Structural Engineering and Mechanics
• /
• 제60권3호
• /
• pp.387-404
• /
• 2016

In this paper, the response and failure of sharp-notched 6061-T6 aluminum alloy circular tubes with five different notch depths of 0.4, 0.8, 1.2, 1.6 and 2.0 mm subjected to cyclic bending were experimentally and theoretically investigated. The experimental moment-curvature relationship exhibits an almost steady loop from the beginning of the first cycle. And, the notch depth has almost no influence on its relationship. However, the ovalization-curvature relationship exhibits a symmetrical, increasing, and ratcheting behavior as the number of cycles increases. In addition, a higher notch depth of a tube leads to a more severe unsymmetrical trend of the ovalization-curvature relationship. Focusing on the aforementioned relationships, the finite element software ANSYS was used to continue the related theoretical simulation. Furthermore, the five groups of tubes tested have different notch depths, from which five unparallel straight lines can be observed from the relationship between the controlled curvature and the number of cycles required to produce failure in the log-log scale. Finally, a failure model was proposed to simulate the aforementioned relationship. Through comparison with the experimental data, the proposed model can properly simulate the experimental data.

• 한국인터넷방송통신학회논문지
• /
• 제16권6호
• /
• pp.287-294
• /
• 2016

APT(Advanced Persistent Threat)공격은 기관, 기업의 정보통신 설비에 대한 중단 또는 핵심정보의 획득을 목적으로 장기간 IT인프라, 업무환경, 임직원 정보 등의 다양한 정보를 수집하고, 이를 바탕으로 제로데이 공격, 사회공학적기법 등을 이용하여 공격을 실행한다. 악성 시그니처 탐지 등의 단편적인 사이버 위협대응 방법으로는 APT 공격과 같이 고도화된 사이버 공격에 대응하기 어렵다. 본 논문에서는 APT 공격 대응 방안 중 하나로 이종 시스템 로그(Heterogeneous System Log)를 빅데이터로 활용하고, 패턴기반 탐지 방법과 이상 징후 탐지 방법을 병합하여 사이버 침해시도를 탐지하는 모델을 제시하고자 한다.

• 한국환경과학회지
• /
• 제16권8호
• /
• pp.913-920
• /
• 2007

Hydrochloride acid salts of new $N_2O_2$ tetradentate ligands containing amine and phenol N,N'-bis(2-hydroxybenzyl)-o-phenylenediamine(H-BHP), N,N'-bis(5-bromo-2-hydroxybenzyl)-o-phenylenediamine(Br-BHP), N,N'-bis(5-chloro-2-hydroxybenzyl)-o-phenylene-diamine(Cl-BHP), N,N'-bis(5-methyl-2-hydroxybenzyl)-o-phenylene-diamine (Me-BHP) and N,N'-bis(5-methoxy-2-hydroxybenzyl)-o-phenylenediamine(MeO-BHP) were synthesized. The ligands were characterized by elemental analysis, mass and NMR spectroscopy. The elemental analysis showed that the ligands were isolated as dihydrochloride salt. The potentiometry study revealed that the proton dissociation constants$(logK_n{^H})$ of ligands and stability constants $(logK_{ML})$ of transition and heavy metals complexes. The order of the stability constants of each metal ions for ligands was Br-BHP < Cl-BHP > H-BHP < MeO-BHP < Me-BHP.

• Environmental Engineering Research
• /
• 제12권3호
• /
• pp.118-127
• /
• 2007

Between June and November 2002, the atmospheric concentrations and dry deposition fluxes of polycyclic aromatic hydrocarbons (PAHs) in Chonju were measured four times each over five days. The total concentration of PAHs in ambient air was $84\;ng/m^3$, with about 90% existing in the vapor phase. Plots of log ($K_p$) vs. log (${P_L}^0$) indicated that PAHs partitioning was not in equilibrium and the particulate characteristics did not change with seasonal variations. The PAHs fluxes to a water surface sampler (WSS) and a dry deposition plate (DDP) were about 14.15 and $1.92\;{\mu}g/m^2/d$, respectively. The flux of the gaseous phase, acquired by subtracting the DDP from the WSS results, was about $12.23\;{\mu}g/m^2/d$. A considerable correlation was shown between the atmospheric concentrations and deposition fluxes in the gaseous phase, but not in the particulate phase, as the fluxes of the particulate phase were dependent on the physical velocity differences of the particulates based on the particle diameter.

• 한국국방경영분석학회지
• /
• 제36권2호
• /
• pp.85-106
• /
• 2010

최근 정부가 공공부문에 대해 저비용, 고효율을 지속적으로 요구해 옴에 따라 국방부문도 효율성 개선을 위한 노력을 하고 있다. 그러나 군수부대의 효율적 운영에 대한 계량적 분석이 없는 실정으로, 본 연구는 군수부대의 효율적 경영 여부를 평가하기 위한 방법을 제시하고자 한다. 이를 위해 기존 선행연구 고찰을 통해 보급부대의 효율성 평가에 적절한 변수를 선정하여 제시하고, 공공부문 효율성 측정에 유용한 DEA(Data Envelopment Analysis)기법을 활용하여, 야전 보급부대를 대상으로 효율성을 평가한 후 비효율적 조직의 효율성 개선을 위한 방안을 제시하고자 한다.

• 한국물환경학회지
• /
• 제32권6호
• /
• pp.537-545
• /
• 2016

In order to cope with the new and strict government regulations for turbid water discharge from construction sites, this study tested whether synthetic fiber filters can replace conventional best management practices. The filter efficiency was about 10 to 60% with a varying filter depth of 5 to 15cm, presuming extreme storm flow conditions to be in the range of 800 to 1500m/day of filtration rates. Fiber filter acts exactly like a granular filter, i.e. the separation efficiency is directly and inversely proportional to filter depth and rate, respectively. Based on the operational data, we suggested the Log-Log design relationship, which can be used to determine the filter depth and area. Compared to the widely used gravel filter which treats the turbid water at the construction site, about 20% higher efficiency was obtained under similar operating conditions. Cleaning the filter through a simple hand-washing method at the time of break-through, achieved about 90% soil recovery.

• 한국멀티미디어학회논문지
• /
• 제18권12호
• /
• pp.1501-1508
• /
• 2015

In this paper, we describe a case study to improve performance through the load testing of multi-tired system for financial accounts before the system opening. The load test was conducted after the data collection tools(Performance Monitor, DB PSSDiag) were installed. By analyzing the collected log, we were able to identify the main sector requiring performance improvements among the presentation tier, web tier, business logic tier and data tier. The ASP.NET server-down on the web tier could be improved by modifying the parameter values in the configuration file. Some server downs occurred on the business logic tier when a large number of users access at the same time, were more difficult to be solved. By analyzing the hang-dump at the server-down time, we were able to find a process that caused the problem. and we had to modify the relevant codes. For major performance improvements of the data-tier, indices of some queries was optimized by using the built-in DBMS query analyzer, after analyzing the log of long-response-time queries. The problems and solutions considered in this case study will be a reference for the performance improvement of a multi-layer system with the similar structure.

• Ocean and Polar Research
• /
• 제37권4호
• /
• pp.333-340
• /
• 2015

The contrast (fish body to medium ratio) of density and sound speed were measured to estimate acoustic scattering from small juvenile cod (Gadus macrocephalus) with the Kirchhoff-Ray Mode backscatter model. The density contrast was measured by the density-bottle method and the sound speed contrast was estimated by the time of flight method. The results revealed that the measured density contrasts of juvenile cod varied between 1.003 and 1.029 (mean = 1.014, S.D. = 0.01). On the other hand, sound speed contrasts varied between 1.039 and 1.041 (mean = 1.041, S.D. = 0.001). The relationship between averaged target strength (TS) and total length (TL) established by the model were <$TS_{38kHz}$> = 20log(TL) - 68.8 and <$TS_{38kHz}$> = 20log(TL) - 69.4, respectively.

• 한국농공학회논문집
• /
• 제60권4호
• /
• pp.83-91
• /
• 2018

Land reclamation, coastal construction, coastline extension and port construction, all of which involve dredging, are increasingly required to meet the growing economic and societal demands in the coastal zone. During the land reclamation, a portion of landfills are lost from the desired location due to a variety of causes, and therefore prediction of sediment transport is very important for economical and efficient land reclamation management. In this study, laboratory disposal tests were performed using an open channel, and suspended sediment transport was analyzed according to flow velocity and grain size. The relationships between the average and standard deviation of the deposition distance and the flow velocity were almost linear, and the relationships between the average and standard deviation of deposition distance and the grain size were found to have high non-linearity in the form of power law. The deposition distribution of sediments was demonstrated to have log-normal distributions regardless of the flow velocity. Based on the experimental results, modeling of suspended sediment transport was performed using deep neural network, one of deep learning techniques, and the deposition distribution was reproduced through log-normal distribution.