• Ocean Systems Engineering
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• v.10 no.4
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• pp.415-434
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• 2020

Detecting objects is important for the safe operation of ships, and enables collision avoidance, risk detection, and autonomous sailing. This study proposes a ship detection method from images and videos taken at sea using one of the state-of-the-art deep neural network-based object detection algorithms. A deep learning model is trained using a public maritime dataset, and results show it can detect all types of floating objects and classify them into ten specific classes that include a ship, speedboat, and buoy. The proposed deep learning model is compared to a universal trained model that detects and classifies objects into general classes, such as a person, dog, car, and boat, and results show that the proposed model outperforms the other in the detection of maritime objects. Different deep neural network structures are then compared to obtain the best detection performance. The proposed model also shows a real-time detection speed of approximately 30 frames per second. Hence, it is expected that the proposed model can be used to detect maritime objects and reduce risks while at sea.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.1-17
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• 2022

The static design approach in the current code implies that the inherent torsional moment represents the state of zero inertial torsional moments at the center of mass (CM). However, both experimental and analytical results prove the existence of a large amount of the inertial torsional moment at the CM. Also, the definition of eccentricity by engineers, which is referred to as the resistance eccentricity, is defined as the distance between the center of mass and the center of resistance, which is conceptually different from the static eccentricity in the current codes, defined as the arm length about the center of rotation. The difference in the definitions of eccentricity should be made clear to avoid confusion about the torsion design. This study proposed prediction equations as a function of resistance eccentricity based on a resistance eccentricity model with advantages of (1) the recognition of the existence of torsional moment at the CM, (2) the avoidance of the confusion by using resistance eccentricity instead of the design eccentricity, and (3) a clear relationship of applied inertial forces at the CM and resisting forces. These predictions are compared with the seismic responses obtained from time-history analyses of a five-story building structure under moderate and severe earthquakes. Then, the trend of the resistance eccentricity corresponding to the maximum edge drift is investigated for elastic and inelastic responses. The comparison given in this study shows that these prediction equations can serve as a useful reference for the prediction in both the elastic and the inelastic ranges.

• Physical Therapy Rehabilitation Science
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• v.11 no.1
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• pp.78-87
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• 2022

Objective: The purpose of this study was to investigate the effect of high-intensity complex exercise program using whole-body vibration (WBV) and respiratory resistance on pain and dysfunction, psychosocial level, balance ability, and pulmonary function in low back pain (LBP) patients with high obesity. Design: A randomized controlled trial Methods: A total of 44 LBP patients withhigh obesity (body mass index, BMI≥30kg/m²) were randomly assigned to an experimental group (n=22) and a control group (n=22). Both groups underwent a lumbar stabilization exercise program. In addition, the experimental group implemented the high-intensity complex exercise program combined with WBV and respiratory resistance. In order to compare the effects depending on the intervention methods, numeric pain rating scale (NRPS), Roland-Morris disability questionnaire (RMDQ), fear-avoidance beliefs questionnaire (FABQ), balance ability, and pulmonary function were used for measurement. Results: Both groups showed significant differences in NRPS, RMDQ, FABQ, balance ability before and after intervention (p<0.05). In addition, the experimental groupshowed significant difference in the amount of change in RMDQ, balance ability and pulmonary function values than the control group (p<0.05). Conclusions: High-intensity complex exercise program using WBV and respiratory resistance has been proven to be an effective and clinically useful method to decrease dysfunction, increase balance ablilty, and pulmonary function for LBP patients with high obesity.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1788-1791
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• 2010

위치 측정 기술의 발달로 인해 다양한 서비스들이 개발 되어 현대 사회에 제공되고 있다. 이러한 서비스들 중 GPS는 현재 우리 사회에 깊숙이 녹아 들어와 핸드폰, 내비게이션, 배송처리, 차량 위치 파악, 긴급구조서비스, 항공 및 선박 항법장치, DSLR 등 다양한 분야에서 활용되고 있다. GPS는 위성신호를 수신하여 위치를 파악하기 때문에 위성신호를 수신할 때 공간상의 제약이 있고, 매우 민감하게 방해요소에 의해 간섭을 받을 수 있다. 차량이 충돌위험 발생시 GPS가 방해요소로 인해 수신되지 않으면 충돌회피를 위한 시스템이 제대로 작동하지 못할 우려가 있다. 본 논문에서는 GPS가 수신율이 떨어지는 터널, 고가도로, 지하주차장과 같은 장소에서의 WLAN을 기반으로 한 위치측정 기술을 이용하여 차량의 충돌회피를 방지하기 위한 프로토콜을 제안한다.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.539-543
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• 2005

The research presented in this paper enables real-time 3D modeling to help make construction processes ultimately faster, more predictable and safer. Initial research efforts used an emerging sensor technology and proved its usefulness in the acquisition of range information for the detection and efficient representation of static and moving objects. Based on the time-of-flight principle, the sensor acquires range and intensity information of each image pixel within the entire sensor's field-of-view in real-time with frequencies of up to 30 Hz. However, real-time working range data processing algorithms need to be developed to rapidly process range information into meaningful 3D computer models. This research ultimately focuses on the application of safer heavy equipment operation. The paper compares (a) a previous research effort in convex hull modeling using sparse range point clouds from a single laser beam range finder, to (b) high-frame rate update Flash LADAR (Laser Detection and Ranging) scanning for complete scene modeling. The presented research will demonstrate if the FlashLADAR technology can play an important role in real-time modeling of infrastructure assets in the near future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.194-195
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• 2023

Recently, Maritime Autonomous Surface Ship(MASS) technology has attracted attention as a key technology for ship safety, efficiency, and economic feasibility in the marine field. Decision-making by the navigator's Situation Awareness (SA) for remote control on shore is expected to play an important role in ship collision avoidance. In this study, the navigator's decision-making time for the collision situation was measured.

• ETRI Journal
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• v.45 no.5
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• pp.887-898
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• 2023

Aerial base stations (ABSs) seem promising to enhance the coverage and capacity of fifth-generation and upcoming networks. With the flexible mobility of ABSs, they can be positioned in air to maximize the number of users served with a guaranteed quality of service (QoS). However, ABSs may be overloaded or underutilized given inefficient placement, and user association has not been well addressed. Hence, we propose a three-dimensional ABS placement scheme with a delay-QoS-driven user association to balance loading among ABSs. First, a load balancing utility function is designed based on proportional fairness. Then, an optimization problem for joint ABS placement and user association is formulated to maximize the utility function subject to statistical delay QoS requirements and ABS collision avoidance constraints. To solve this problem, we introduce an efficient modified gray wolf optimizer for ABS placement with a greedy user association strategy. Simulation results demonstrate that the proposed scheme outperforms baselines in terms of load balancing and delay QoS provisioning.

• Journal of Gifted/Talented Education
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• v.11 no.3
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• pp.99-129
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• 2001

The purpose of the present study is to determine antecedents in the area of subject matters and to compare these factors between average student group and gifted student group, based on the implicit theory proposed by Sternberg(1993). The average group consisted of 350 primary school students (boy 172; girl 178) from a primary school and 380 middle school students (boy 221; girl 159) from a middle school in Taejeon Metropolitan City. The gifted group consisted of 181 primary school students (boy 130; girl 51) and 154 middle school students (boy 92; girl 62) from the Center for the Gifted Education of the Kong Ju National University. A questionnaire was developed by the authors. It consisted of 30 research questions related to reasons why they studied those subject matters hard. It took about 40 minutes to complete the questionnaire. Several exploratory factor analyses and confirmative analyses were conducted. The main results obtained were as follows: The subject matters all the students of the present study were English and Math. The main reasons why they studied those subject matters hard were interest, utility, competition, self-esteem, entrance examination, recognition, punishment avoidance, etc. A factor analysis revealed that, for the elementary school students, recognition and interest were factors for the average students, whereas knowledge acquisition was an unique factor for the gifted. Utility was common factor for both groups. A factor analysis revealed that, for the middle school students, knowledge acquisition was the main factor for the average students, whereas competition was the unique factor for the gifted. Recognition, interest, and utility were common factors for the both groups.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.299-323
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• 2018

This study confirmed the life career branching points, and studied qualitatively the career strategy and career identity at that time. The participants in this study were three students from third graders of middle school, three ones from third graders of high school, and three before and after college graduation, which correspond to the vertical transition stage of school education. Three participants were selected before and after 30 years of age, three before and after 40 years of age, and three before and after 60 years of age. Subject analysis of the contents of the 18 interviews, showed that the life career branching point appeared in middle school grade 3, high school grade 3, until employment after graduation, within 3 years after entering their first job, early 40 years, 60 years old, and 80 years old. Second, external situations were due to the influence of important others, or external stimuli, environment, and career events. Third, negative emotions were repeated for each life career branching point. Fourth, as a result of the interview, the career identity confusion was repeated in every life career branching point. Fifth, the career strategy at the life career branching point was categorized as an approach strategy and avoidance strategy.

• Journal of Science Education
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• v.45 no.1
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• pp.55-68
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• 2021

The modern society is rapidly changing, and accordingly, the required teacher image is changing as well. Middle school students are immature, when they undergo major changes both physically and mentally, and teachers have a great influence. How students perceive the teacher determines the relationship between teachers and students. Therefore, it is necessary to analyze what kind of teacher image middle school students want. The purpose of this study is to analyze the image of a science teacher who prefers and avoids each class situation perceived by middle school students. To this end, 502 middle school students were divided into five classes: class type, class material presentation method, subject instruction method, subject content explanation method, and class atmosphere, and the image of science teacher who prefers and avoids is described in an open format. Concepts presented by middle school students were analyzed through semantic network analysis (SNA). The conclusions of this study are as follows: first, in order to make middle school students interested in science, an inquiry-centered experiment class should be conducted. Second, the change of class by science teacher can change it into preferred science class. Third, student-centered classes should be conducted according to the level so that students can understand. Finally, science teachers continue to strive through communication between science teachers and students, and students and students, and look forward to changes in science classes through this.