• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.491-497
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• 2009

This paper presents the results of accelerated pavement tests (APT) that simulate permanent deformation (rutting) of asphalt concrete pavements under different temperatures and loading courses. Also, finite element (FE) analysis has been conducted to predict the test results. Test section for APT is the same as one of test sections at Korea Expressway Corporation test road and is subjected to a constant moving dual tire wheel load of APT at three different temperatures: 30, 40, $50^{\circ}C$. The moving wheel is applied at different loading courses within a 75cm wide wheel path to account for traffic wandering. Also, the effect of wandering on permanent deformation development is investigated numerically with three wandering schemes. In this study, ABAQUS is adopted to model APT pavement section with plain stain elements and creep strain rate model is used to take into account viscoplastic stain of asphalt concrete mixtures, and elastic layer properties are back-calculated from FWD measurements. Plus, the effect of boundary condition and subgrade on FE permanent deformation predictions is investigated. A full FE model that accounted for subgrade provided more realistic rut depth predictions, indicating subgrade has contributed to surface rutting.

• Journal of Service Research and Studies
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• v.11 no.2
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• pp.1-19
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• 2021

This study was conducted to derive a model of a sustainable politics and administration system that will enhance human happiness. A new long-term sustainable development model has been established based on the experience of the politics and administration system over the past thousands of years. Currently, the democratic political system and the bureaucratic administrative system dominate, but they are facing many problems. In this study, we analyzed the politics and administration system experienced by human society, and derived a model of a politics and administration system that is ideal for the present and future societies and is sustainable in the long term. The necessary condition should be a model that can solve the problems of the current politics and administration system. It must be a model that is faithful to the characteristics and essence of modern society. And as a sufficient condition to ensure long-term sustainability, it must be based on the common principles of human society. After analyzing the problems of the current system and analyzing the conditions required for the new system, the axioms that are the basis of the politics and administration system were presented. Based on the axioms, the structure and operation model of a new politics and administration system were derived. The derived model was named as a servicism politics and administration system. It is a dynamic model in which two opposing opponents recognize each other's contradictions and balance them dialectically in the space-time dimension.

• Korean Journal of Remote Sensing
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• v.38 no.6_2
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• pp.1723-1735
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• 2022

Landslides are one of the most prevalent natural disasters, threating both humans and property. Also landslides can cause damage at the national level, so effective prediction and prevention are essential. Research to produce a landslide susceptibility map with high accuracy is steadily being conducted, and various models have been applied to landslide susceptibility analysis. Pixel-based machine learning models such as frequency ratio models, logistic regression models, ensembles models, and Artificial Neural Networks have been mainly applied. Recent studies have shown that the kernel-based convolutional neural network (CNN) technique is effective and that the spatial characteristics of input data have a significant effect on the accuracy of landslide susceptibility mapping. For this reason, the purpose of this study is to analyze landslide vulnerability using a pixel-based deep neural network model and a patch-based convolutional neural network model. The research area was set up in Gangwon-do, including Inje, Gangneung, and Pyeongchang, where landslides occurred frequently and damaged. Landslide-related factors include slope, curvature, stream power index (SPI), topographic wetness index (TWI), topographic position index (TPI), timber diameter, timber age, lithology, land use, soil depth, soil parent material, lineament density, fault density, normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) were used. Landslide-related factors were built into a spatial database through data preprocessing, and landslide susceptibility map was predicted using deep neural network (DNN) and CNN models. The model and landslide susceptibility map were verified through average precision (AP) and root mean square errors (RMSE), and as a result of the verification, the patch-based CNN model showed 3.4% improved performance compared to the pixel-based DNN model. The results of this study can be used to predict landslides and are expected to serve as a scientific basis for establishing land use policies and landslide management policies.

• The Journal of the Korea Contents Association
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• v.17 no.8
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• pp.1-13
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• 2017

In this paper, a research model was designed to investigate the factors influencing the intention to use of mobile easy payment services in China. Our research model includes the service factors(instant connectivity, economic and security), social factors(subjective norms and image), the user's individual factors(self-efficacy personal innovativeness and suitability), perceived ease of use, perceived usefulness and intention to use. A survey was conducted to collect the data with users who have had the actual using experience about mobile easy payment services. In this research, the data were collected by online survey, and in final analysis, 439 users' questionnaires were used. The empirical paper proves research hypothesis by using SPSS 22.0 and AMOS 23.0. The results of the study are as follows: the mobile easy payment service factors, social factors and the user's individual factors partially give positive effects to perceived ease of use and perceived usefulness; perceived ease of use gives positive effects to perceived usefulness. In addition, perceived ease of use and perceived usefulness have positive effects to on intention to use.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.171-181
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• 2013

Recently, ground penetrating radar(GPR) has been widely used in detecting metallic and nonmetallic buried landmines and a number of related researches have been reported. A novel preprocessing method is proposed in this paper to flag potential locations of buried mine-like objects from GPR array measurements. GPR operates by measuring the reflection of an electromagnetic pulse from discontinuities in subsurface dielectric properties. As the GPR pulse propagates in the geologic medium, it suffers nonlinear attenuation as the result of absorption and dispersion, besides spherical divergence. In the proposed algorithm, a logarithmic transformed regression model which successfully represents the time-varying signal amplitude of the GPR data is estimated at first. Then, background signals may be densely distributed near the regression model and candidate signals of targets may be far away from the regression model in the time-amplitude space. Based on the observation, GPR signals are decomposed into candidate signals of targets and background signals using residuals computed from the estimated value by regression and the measurement of GPR. Candidate signals which may contain target signals and noise signals need to be refined. Finally, targets are detected through the refinement of candidate signals based on geometric signatures of mine-like objects. Our algorithm is evaluated using real GPR data obtained from indoor controlled environment and the experimental results demonstrate remarkable performance of our mine-like object detection method.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.605-614
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• 2002

Amount of the web traffic web server handles are explosively increasing, which requires that the performance of the web server should be improved for the various web services. Although the analysis for the HTTP traffic with the proper tuning for the web server is essential, the research relevant to the subject are insignificant. In particular, although most of applications are implemented over HTTP 1.1 protocol, the researches mostly deal with the performance evaluation of the HTTP 1.0 protocol. Consequently, the modeling approach and the performance evaluation over HTTP 1.1 protocol have not been well formed. Therefore, basing on the HTTP 1.1 protocol supporting persistent connection, we present an analytical end-to-end tandem queueing model for web server to consider the specific hardware configuration inside web server beginning at accepting the user request until completing the service. we compare various performances between HTTP 1.0 and HTTP 1.1 under the overloading condition, and then analyze the characteristics of the HTTP traffic that include file size requested to web server, the OFF time between file transfers, the frequency of requests, and the temporal locality of requests. Presented model is verified through the comparing the server throughput according to varying requests rate with the real web server. Thereafter, we analyze the performance evaluation of the web server, according to the interrelation between TCP Listen queue size, the number of HTTP threads and the size of the network buffers.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.164-174
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• 2008

In this study we try to identify the three-dimensional mixing characteristics of Seomjin River discharges in Seomjin River Estuary and Gwangyang Bay using a seasonal field observation (CTD) during spring tide and a three-dimensional numerical model with EFDC (Environmental Fluid Dynamics Code). The tidal elevation conditions of the four main tidal harmonic constituents on the open boundary and river discharges and thermal effluents at the specific boundary are considered. The calculated harmonic constants of tide and tidal current agreed well with those of observations at two stations for tide and two stations for tidal current. The model successfully reproduced well known the estuarine circulation in Seomjin River Estuary where tide and river discharges are dominant forcings. In the winter mean discharges case, tidal currents move Seomjin River discharges in Seomjin River mouth and in the summer mean discharges case, river flows move Seomjin River discharges near ae Seomjin River Estuary. A three-dimensional mixing characteristics of Seomjin River Estuary show well a three-dimensional estuarine circulation and thermal effluents effect to the seasonal variation of river discharges.

• Journal of Energy Engineering
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• v.24 no.1
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• pp.114-122
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• 2015

In the high convective gas flow condition, irregular shaped water waves from which droplet entrainment occurs are generated under horizontally stratified two-phase flow condition. KAERI proposed a new mechanistic droplet entrainment model based on the momentum balance equation consisting of the shear stress, surface tension, and gravity forces. However, this model requires correlation or experimental data of several physical parameters related to the wave characteristics. In the present study, we tried to measure the physical parameters such as wave slope, wave hypotenuse length, wave velocity, wave frequency, and wavelength experimentally. For this, an experiment was conducted in the horizontal rectangular channel of which width, height, and length are, respectively, 40 mm, 50 mm, and 4.2 m. In the present test, the working fluids are chosen as air and water. The PIV technique was applied not only to obtain images for phase interface waves but also to measure the velocity field of the water flow. Additionally, we developed the parallel wire conductance probe for the confirmation of wave height from PIV image. Finally, we measured the physical parameters to be used in the validation of new droplet entrainment model.

• The Transactions of the Korea Information Processing Society
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• v.13 no.4
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• pp.199-207
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• 2024

Local reservoirs are crucial sources for agricultural water supply, necessitating stable water level management to prepare for extreme climate conditions such as droughts. Water level prediction is significantly influenced by local climate characteristics, such as localized rainfall, as well as seasonal factors including cropping times, making it essential to understand the correlation between input and output data as much as selecting an appropriate prediction model. In this study, extensive multivariate data from over 400 reservoirs in Jeollabuk-do from 1991 to 2022 was utilized to train and validate a water level prediction model that comprehensively reflects the complex hydrological and climatological environmental factors of each reservoir, and to analyze the impact of each input feature on the prediction performance of water levels. Instead of focusing on improvements in water level performance through neural network structures, the study adopts a basic Feedforward Neural Network composed of fully connected layers, batch normalization, dropout, and activation functions, focusing on the correlation between multivariate input data and prediction performance. Additionally, most existing studies only present short-term prediction performance on a daily basis, which is not suitable for practical environments that require medium to long-term predictions, such as 10 days or a month. Therefore, this study measured the water level prediction performance up to one month ahead through a recursive method that uses daily prediction values as the next input. The experiment identified performance changes according to the prediction period and analyzed the impact of each input feature on the overall performance based on an Ablation study.

• 한국HCI학회:학술대회논문집
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• 2007.02b
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• pp.270-277
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• 2007

가상공간에서 사용자들은 온라인 커뮤니티(Online Community)로 관계(Relationship)를 맺고, 같은 관심사를 가지고 공감대를 형성하는 일이 하나의 디지털문화로 형성되었다. 이러한 가상공간에서 자신을 대변할 수 있는 또 다른 나, 즉 아바타(Avatar)에 대한 선호가 증가하고 있으며, 사용목적에 따른 사용자 감성의 반영으로 아바타 디자인이 다양한 형태로 발전하고 있다. 아바타의 근원은 분신(分身) 화신(化身)을 뜻하는 산스크리스트어 '아바따라(avataara)'에서 유래되었으며, 인터넷시대가 열리면서 3차원이나 가상현실게임 또는 웹에서의 채팅 등을 즐길 때 사용자를 대신하는 그래픽 아이콘으로 표상되면서 인터넷 상에서 자신을 대표하는 분신으로 정의되고 있다. 본 연구의 목적은 인터넷 매체 서비스 이용자의 아바타 사용에 따른 유형별 특성에 관한 것으로서, 이 연구를 통해 아바타 디자인의 시각적 표현요소에 효과적으로 활용될 수 요인을 찾고자 하였다. 분석을 위해 인터넷 공동체 집단을 미니홈피/블로그, 채팅, 게임으로 구분하였으며, 아바타 이용자들이 이와 같은 커뮤니티를 이용할 때 어떤 목적에 따라 사용하고 있으며, 그들이 아바타를 선택할 때 어떤 유형별 특성이 나타나는가를 실증하고자 하였다. 이것은 아바타 이용자들이 자신이 표현하려는 아바타 이미지와의 관계를 파악함으로써 가상세계에서 표출하는 아바타 사용 목적에 맞는 유형을 설명할 수 있을 것이다. 따라서 아바타 이용자의 특성을 파악하여 그들의 감성을 반영하는 디자인 전략을 세울 수 있다. 연구방법은 아바타의 개념과 유형분류, 그리고 미니홈피/블로그, 게임, 채팅의 이론적 논의 및 근거제시를 위한 문헌연구를 하였으며, 아바타 이용목적에 따른 유형별 특성을 심도 있게 파악하기 위해 질적연구(Qualitative)로서 표적집단면접(Focus Group Interview)을 실시하였으며, 그에 따른 내용분석과 표현분석을 하였다. 그리고 이것을 보다 객관적으로 검증(verification)하기 위해 양적연구(Quantitative)를 병행하였다. 조사대상은 아바타를 이용해 본 경험이 있는 384명의 학생들이며, 성별 연령별에 따른 분류를 통해 각 조사대상자별 특징을 발견하고자 하였다. 조사를 통해 미니홈피/블로그, 채팅, 게임의 서비스 공간에서 보여 지는 각각의 특성에 맞게 아바타 이용자들은 자신이 표현하려는 아바타의 유형에서 선호의 차이를 나타내고 있음을 알 수 있었다. 결과적으로 아바타사용자의 인터넷 매체 이용목적에 따른 유형별 특성을 파악할 수 있었으며, 향후 사이트(site)의 특성에 따라 사용자의 감성선호를 고려한 아바타 디자인 전략과 그 모델(Design model)을 제시할 수 있을 것이다.