• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.111-129
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• 2007

The standard construction manual of the SDA(Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 405 dynamic pile load tests and 30 static pile load tests were performed for 265 test piles, which were installed by the SDA piling method in 33 sites in Korea. The results of the pile load tests showed that the end bearing capacity of the SDA augered piles depended on the property of various soil stratums and did not agree with ones estimated by the existing formula based on several standard design codes. On the basis of the pile load test results, four formulas were presented according to bearing stratums to estimate quantitatively the unit end bearing capacity of the SDA augered piles. The formulas for the unit end bearing capacity of piles on soils or weathered rocks were related to N-value given by SPT(Standard Penetration Test), while the unit end bearing capacity on bedrock was suggested to be more than 1500 $tf/m^2$. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles. In order to use correctly the presented formulas, the quality of Standard Penetration Test should be controlled precisely. Also it is desirable to choose a pilot construction site, where both dynamic and static pile load tests are performed.

• Journal of Industrial Convergence
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• v.21 no.7
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• pp.29-39
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• 2023

In the recent period, there have been numerous earthquakes both domestically and internationally, and buildings in South Korea are particularly vulnerable to seismic design and earthquake damage. Therefore, the objective of this study is to discover an effective method for assessing the seismic vulnerability of buildings and conducting a density analysis of high-risk structures. The aim is to model this approach and validate it using data from pilot area(Seoul). To achieve this, two modeling techniques were employed, of which the predictive accuracy of the statistical analysis technique was 87%. Among the machine learning techniques, Random Forest Model exhibited the highest predictive accuracy, and the accuracy of the model on the Test Set was determined to be 97.1%. As a result of the analysis, the district rating revealed that Gwangjin-gu and Songpa-gu were relatively at higher risk, and the density analysis of at-risk buildings predicted that Seocho-gu, Gwanak-gu, and Gangseo-gu were relatively at higher risk. Finally, the result of the statistical analysis technique was predicted as more dangerous than those of the machine learning technique. However, considering that about 18.9% of the buildings in Seoul are designed to withstand the Seismic intensity of 6.5 (MMI), which is the standard for seismic-resistant design in South Korea, the result of the machine learning technique was predicted to be more accurate. The current research is limited in that it only considers buildings without taking into account factors such as population density, police stations, and fire stations. Considering these limitations in future studies would lead to more comprehensive and valuable research.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.12
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• pp.1846-1854
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• 2022

The sophistication and diversification of mission equipment for surveillance and reconnaissance is leading to a demand for large-capacity public data links. Overseas, a T4 class(274Mbps) common data link was applied to the Global hwak, a high-altitude unmanned aerial vehicle, and various research and development are being conducted in Korea. In this paper, we propose a structure in which pilot is additionally applied to improve SNR performance while minimizing data transmission rate loss in the DVB-S2 frame structure, which is a european satellite broadcasting standard, for high-capacity transmission of T4 class or higher in the common data link. For the performance evaluation of the proposed structure, the performance of the DVB-S2 was compared and analyzed by simulating the UAV data link channel environment. As a result of simulation, 0.15% of transmission rate loss occurred at T4 class transmission rate compared to DVB-S2 in the proposed structure, but improved SNR reception performance of 0.2~0.3dB was confirmed in the UAV channel environment.

• 한국노년학
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• v.31 no.2
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• pp.381-400
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• 2011

The purpose of this study is to develop the scale on Selection, Optimization, Compensation(SOC) model as successful aging strategies of Korean Elderly. In first phase of the study, 64 pilot items were collected from researcher's indepth interviews with a purposive sample group of 24 elderly people(16 items) and original SOC scale(48 items). To analyze the factor structure and to verify the validity of the scale, 592 questionnaires collected from survey were divided randomly into 300 developmental samples and 292 validity samples. The items were examined exploratory with developmental samples and confirmatory factor analysis with developmental samples. Two factor analysis supported four factor structure of the SOC consisted of 20 items. Four factors are as follows: 'Elective Selection', 'Loss-Based Selection', 'Opimization', 'Compensation'. The cronbach's alpha estimate of the scale was .930. This scale of four factor model exhibited good fit, assessed by overall fit measure criteria(TLI=.939, CFI=.947, RMSEA=.058). The result of analysis by item response theory for SOC scale is satisfatory. Also, SOC scale was significantly related to the two successful aging scales for Korean elderly and life satisfation scale(SWLS). These results proved the validity of the scale.

• 한국노년학
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• v.29 no.3
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• pp.917-933
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• 2009

This study examined the factors affecting forms of long-term care service use by elderly and the forms of use are classified facility care service, home care service, and unused. It is used data from the 2nd pilot program for the Long Term Care Insurance scheme and it is analysed 5,497 cases. Multi-nominal regression is used. According to the results, women use formal service more than man do, and wowen use facility care than home care. Those who eligible for National Basic Livelihood Security System(NBLSS) are shown to have higher use of formal care(especially facility care) than the middle income class, and the low income class than the middle income class has lower use of formal care. In addition, higher the family care is available, lower the taking part in the service. The big cities and mid sized cities than rural are used the formal service and moreover mid sized cities are used facility care than home care. Furthermore, the level of care need is determinants of service use and function of ADL, IADL, and abnormal behavior is also determinants of formal service(especially facility care). But nursing need and rehabilitation need are not determinants of formal service use. Based on the results, the recommendations are developed and implemented for the improvement the elderly long-term care insurance.

• Korean small business review
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• v.39 no.3
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• pp.57-76
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• 2017

While the unemployment rate is rising rapidly due to recent economic recession at home and abroad, university students' reluctance to apply for jobs in Small and Medium Enterprises (SME's) causes instability in manpower supply and demand and social unrest. To provide insights for solving the problem, this study explores how beliefs and attitudes of university students influence their intention to apply for jobs in SME's using Theory of Planned Behavior proposed by Icek Ajzen. This study followed the 2-stage survey methodology suggested by Ajzen. In the first stage of pilot study, a small sample of university students was used to illicit readily accessible behavioral outcomes, normative referents, and control factors. In the second stage of main study, the standard questionnaire was designed and administered and data were collected and analysed using the PLS Structural Equation Modeling (SEM) technique. PLS-SEM was used instead of Covariance Based (CB)- SEM considering the exploratory nature of this study. In overall, the results showed that TPB is very effective in explaining and predicting the university student's intention to apply for jobs in SEM's. Gender turned out to be a significant moderator variable in the relations between intention and its influence factors. Student's scholastic performance showed a negative correlation with intention. More research efforts need to be exerted to better understand university student's job seeking behavior.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.857-862
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• 2023

In order for an autonomous ship to arrive near the pier and automatically berth without the help of a tugboat or pilot, it is necessary to recognize the pier and calculate the thruster output and output angle for berthing to the pier at a fixed berthing speed under given external force conditions. Therefore, in this study, the external force and moment acting on the ship while berthing were analyzed, and the thruster output calculation for automatic berthing was designed and the basic concept for the development of the automatic berthing program was designed. The wind pressure applied to the hull by the wind while the ship is berthing was calculated based on the wind pressure area and the wind direction angle and the turning moment to rotate the ship according to the transverse force of the ship was calculated. Considering the force acting on the ship and the turning moment during berthing, a theoretical formula was presented to calculate the thruster output and output angle for berthing parallel to the pier, and the turning due to other variables was controlled by the PID controller. In addition, the basic concept for program development was presented by analyzing the input elements necessary for the theoretical formula.

• International Journal of Computer Science & Network Security
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• v.23 no.10
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• pp.1-10
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• 2023

This paper proposes a method to extend Inter-Carrier Interference (ICI) canceling Orthogonal Frequency Division Multiplexing (OFDM) receivers for 5G mobile systems to spatial multiplexing 2×2 MIMO (Multiple Input Multiple Output) systems to support high-speed ground transportation services by linear motor cars traveling at 500 km/h. In Japan, linear-motor high-speed ground transportation service is scheduled to begin in 2027. To expand the coverage area of base stations, 5G mobile systems in high-speed moving trains will have multiple base station antennas transmitting the same downlink (DL) signal, forming an expanded cell size along the train rails. 5G terminals in a fast-moving train can cause the forward and backward antenna signals to be Doppler-shifted in opposite directions, so the receiver in the train may have trouble estimating the exact channel transfer function (CTF) for demodulation. A receiver in such high-speed train sees the transmission channel which is composed of multiple Doppler-shifted propagation paths. Then, a loss of sub-carrier orthogonality due to Doppler-spread channels causes ICI. The ICI Canceller is realized by the following three steps. First, using the Demodulation Reference Symbol (DMRS) pilot signals, it analyzes three parameters such as attenuation, relative delay, and Doppler-shift of each multi-path component. Secondly, based on the sets of three parameters, Channel Transfer Function (CTF) of sender sub-carrier number n to receiver sub-carrier number l is generated. In case of n≠l, the CTF corresponds to ICI factor. Thirdly, since ICI factor is obtained, by applying ICI reverse operation by Multi-Tap Equalizer, ICI canceling can be realized. ICI canceling performance has been simulated assuming severe channel condition such as 500 km/h, 8 path reverse Doppler Shift for QPSK, 16QAM, 64QAM and 256QAM modulations. In particular, 2×2MIMO QPSK and 16QAM modulation schemes, BER (Bit Error Rate) improvement was observed when the number of taps in the multi-tap equalizer was set to 31 or more taps, at a moving speed of 500 km/h and in an 8-pass reverse doppler shift environment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.151-171
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• 2023

This study analyzed farmer's responses to the pilot project in advance of the nationwide expansion of the farm-customized early warning service for weather risk management by conducting a survey among all farmers who received text messages of this service. We analyzed not only the satisfaction of farmers with the early warning service, but also the effectiveness of the service in preventing agrometeorological disasters through cross-tabulation analysis of survey results. More than 330 farmers participated in the survey, and more than 60% of the respondents said that they had prevented or mitigated crop disasters by using the early warning service. The cross-tabulation analysis showed that farmers who perceived the field-specific weather information of the early warning service to be more accurate than the weather forecast were statistically significantly more likely to prevent crop disasters than those who did not. According to our case study, farmers who grew open field fruit crops were particularly sensitive to weather information and confirmed that early warning services, along with disaster prevention facilities, were effective in preparing for freezing and frost injury that had been occurring frequently under the influence of climate change. This study is significant in that it is the first to systematically analyze the effectiveness of the farm-customized early warning service for weather risk management based on extensive surveys. It is expected to contribute to exploring ways to develop the service ahead of the nationwide expansion of the early warning service in the near future.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.1
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• pp.69-75
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• 2023

In recent years, there has been a growing interest in deep learning-based animal pose estimation, especially in the areas of animal behavior analysis and healthcare. However, existing animal pose estimation techniques do not perform well when body parts are occluded or not present. In particular, the occlusion of dog tail or ear might lead to a significant degradation of performance in pet behavior and emotion recognition. In this paper, to solve this intractable problem, we propose a simple yet novel framework for pet pose estimation where pet pose is predicted on an outpainted image where some body parts hidden outside the input image are reconstructed by the image inpainting network preceding the pose estimation network, and we performed a preliminary study to test the feasibility of the proposed approach. We assessed CE-GAN and BAT-Fill for image outpainting, and evaluated SimpleBaseline for pet pose estimation. Our experimental results show that pet pose estimation on outpainted images generated using BAT-Fill outperforms the existing methods of pose estimation on outpainting-less input image.