• Journal of Information Processing Systems
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• v.17 no.1
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• pp.163-177
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• 2021

Many methods of discovering social networking communities or clustering of features are based on the network structure or the content network. This paper proposes a community discovery method based on topic models using a time factor and an unsupervised clustering method. Online community discovery enables organizations and businesses to thoroughly understand the trend in users' interests in their products and services. In addition, an insight into customer experience on social networks is a tremendous competitive advantage in this era of ecommerce and Internet development. The objective of this work is to find clusters (communities) such that each cluster's nodes contain topics and individuals having similarities in the attribute space. In terms of social media analytics, the method seeks communities whose members have similar features. The method is experimented with and evaluated using a Vietnamese corpus of comments and messages collected on social networks and ecommerce sites in various sectors from 2016 to 2019. The experimental results demonstrate the effectiveness of the proposed method over other methods.

• Journal of information and communication convergence engineering
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• v.20 no.3
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• pp.189-194
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• 2022

As non-face-to-face activities have become commonplace, online video conferencing platforms have become popular collaboration tools. However, existing video conferencing platforms have a structure in which one side unilaterally exchanges information, potentially increase the fatigue of meeting participants. In this study, we designed a video conferencing platform utilizing virtual reality (VR), a metaverse technology, to enable various interactions. A virtual conferencing space and realistic VR video conferencing content authoring tool support system were designed using Meta's Oculus Quest 2 hardware, the Unity engine, and 3D Max software. With the Photon software development kit, voice recognition was designed to perform automatic text translation with the Watson application programming interface, allowing the online video conferencing participants to communicate smoothly even if using different languages. It is expected that the proposed video conferencing platform will enable conference participants to interact and improve their work efficiency.

• ETRI Journal
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• v.45 no.6
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• pp.1046-1055
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• 2023

We introduce a display for virtual-reality (VR) fire training. Firefighters prefer to wear and operate a real breathing apparatus while experiencing full visual immersion in a VR fire space. Thus, we used a thin head-mounted display (HMD) with a light field and folded optical system, aiming to both minimize the volume for integration in front of the face into a breathing apparatus and maintain adequate visibility, including a wide viewing angle and resolution similar to that of commercial displays. We developed the optical system testing modules and prototypes of the integrated breathing apparatus. Through iterative testing, the thickness of the output optical module in front of the eyes was reduced from 50 mm to 60 mm to less than 20 mm while maintaining a viewing angle of 103°. In addition, the resolution and image quality degradation of the light field in the display was mitigated. Hence, we obtained a display with a structure consistent with the needs of firefighters in the field. In future work, we will conduct user evaluation regarding fire scene reproducibility by combining immersive VR fire training and real firefighting equipment.

• Journal of the Korean Society of Floral Art and Design
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• no.41
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• pp.133-153
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• 2019

This study is about the development and creation of the public installation to enhance the contact chances with plants for the city dwellers who are living in the environment of limited green space. The researcher tried to create a floral art work at an island type bus stop on the central bus only lane, where the passers-by can enjoy the contact with plants for a second on that crowded space. The researcher made the study of various related cased world-widely and existing island type bus stop on the central bus only lane. The researcher also made pre-creation study of applicable forms and elements, and developed the prototype of the installation on the base of that study. Therefore the researcher created 1 installable screen type floral art work offering abundant contact experience to the viewers which has multiple shelves in the vertical frame to fit and be substituted by the designated wall unit of the island type bus stop structure. Also the researcher developed the prototypes of 2 small interior pieces. The meaning of this study can be found in the contribution of increasing visual experiencing rate of green space and chances of experiencing plants to create positive psychological, emotional effects by developing floral art works to be installed at crowded urban public space.

• Korean Journal of Heritage: History & Science
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• v.54 no.1
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• pp.138-163
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• 2021

The Buyeo Wangheungsa Temple was excavated 15 times by the Buyeo National Research Institute of Cultural Heritage by 2015. In doing this, it was confirmed that the attached buildings were placed in the east and west along with the central Sangharama building. Various building sites were established in the western section of the temple, and various buildings were placed inside, and this pattern was estimated in the eastern section. In this article, the structure and function of the attached buildings of the Wangheungsa Temple were focused on the planar structure and excavated artifacts. The most distinctive feature of the attached buildings of the Wangheungsa Temple is their construction alongside the central Sangharama building. It is different from the building to the Neungsan-ri Temple, which was expanded gradually. The attached buildings in the east and west of the lecture hall are presumed to be living space for monks who used solitary rooms, and the attached buildings in the east and west of the main hall were a combination of public work space used for things such as administration, ceremonies, and reception. Next, looking at the outer space of the central Sangharama, the western section was likely constructed at the same time as the central Sangharama. However, if you look at the building site inside the western section, the function has been changed in two stages. The first stage was a ritual space, and it is evident that the western section has a separate entrance and sidewalk and that the workshop was used as a monastery space in the second stage. Finally, there is a distinct possibility that the eastern part of the complex was an important section. Although this space is presumed to be composed of triple towers and halls, it must be have been approached in various ways and included structures related to the operation of temples, such as the monastery space. From this point on, the overall appearance of Baekje temples can be recovered through access to temple structures in a wide variety of ways, including studies of the attached buildings.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.731-742
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structure. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process is repeated in the lower ground of the excavation so that it can affect existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effects of the ground excavation and the new structure load on the existing tunnel were investigated by large - scale experiment and numerical analysis. For this purpose, a large model tester with a size reduced to 1/5 of the actual size was constructed, and model tests and numerical analyzes were carried out to investigate the effects of the excavation of the body ground by maintaining the distance between the excavation floor and the tunnel ceiling constant, The impacts were identified. As a result of the study, it was confirmed that the deeper the excavation depth, the larger the influence on the existing tunnel. At the same distance, it was confirmed that the tunnel displacement increased with the increase of the building load, and the ground stress increased up to 2.4 times. From this result, it was confirmed that the effect of the increase of the underground stress on the existing tunnel is affected by the increase of the building load, and the influence of the underground stress is decreased from the new load width above 3.0D.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.8
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• pp.692-700
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• 2014

In this work, satellite FE (finite element) model updating for the prediction of the effect of micro-vibration is described. In the case of satellites launched in low earth orbit, high agility and more mission accomplishments are required by the customer in order to procure many images from satellites. To achieve the goal, many mechanisms, including high capacity wheels and antennas with multi-axis gimbals have been widely adopted, but they become a source of micro-vibration which could significantly deteriorate the quality of images. To investigate the effect due to the micro-vibration in orbit on the ground, a prediction is conducted through an integrated model coupling the measured jitter sources with FE (finite element) model. Before prediction, the FE model is updated to match simulation results with the modal survey test. Subsequently, the quality of FE model is evaluated in terms of frequency deviation error, the resemblance of mode shapes and FRFs (frequency response functions) between test and analysis.

• Journal of architectural history
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• v.22 no.4
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• pp.35-44
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• 2013

This paper looked into the structure of and changes in the building process of Gijang mountain fortress and its receiving reservoir by analyzing data from an excavation investigation. The structure of the receiving reservoir may be classified into a flat form, stone sheath, floor facility, wall facility, and entry and exit facility. The flat form of the Gijang mountain fortress and receiving reservoir is round. Concerning the sectional form, the wall was obliquely excavated in the trapezoid. As a stone sheath building method, it was built by undertaking a range work of oblong stone materials in a clockwise direction on a stamped soil floor. Then, it was treated with stamping using double layers of gray clay and yellowish brown clay on the floor and the wall. Also, in a space between the stamped layers on the floor, herbal plants and a straw mat were laid for waterproofing as well as to prevent sinking. As an entry and exit facility, two facilities were confirmed symmetrically in the southeast and in the northwest. It is believed that they were built additionally during rebuilding after the initial construction. The building process was revealed to have been carried out in 8 stages. Given the structure and excavated remains, the building period is estimated to be the early to mid 7th century for the initial building, the later 9th to 11th centuries for the primary rebuilding, and the later 16th to early 17th centuries for the secondary rebuilding.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.3
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• pp.482-501
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• 2014

Most textbooks of urban geography explain that land value drops down with distance from the Peak Land Value Intersection of urban center. However, There is little rigorous empirical work supporting this belief. Using the publicly notified individual land price data of 2013, this paper examines the structure of land value in urban center with a focus on spatial distribution of land value by land use. As an analytic result, the structure of land price varies between land uses, significantly being different from the classical model of land value in urban space. In residential lands and mixed-use lands for residence and commerce, land price gradient as a function of distance from PLVI is positive and a crater phenomenon even is identified in spatial distribution of land value. The classical model coincides only with land for commerce and office. Nonetheless, predict of land uses by land value function fairly corresponds to Alonso's model.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.776-787
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• 2002

Automation of welding process in shipyards is ultimately necessary, since the welding site is spatially enclosed by floors and girders, and therefore welding operators are exposed to hostile working conditions. To solve this problem, a welding mobile robot that can navigate autonomously within the enclosure has been developed. To achieve the welding task in the closed space, the robotic welding system needs a sensor system for the working environment recognition and the weld seam tracking, and a specially designed environment recognition strategy. In this paper, a three-dimensional laser vision system is developed based on the optical triangulation technology in order to provide robots with 3D work environmental map. Using this sensor system, a spatial filter based on neural network technology is designed for extracting the center of laser stripe, and evaluated in various situations. An environment modeling algorithm structure is proposed and tested, which is composed of the laser scanning module for 3D voxel modeling and the plane reconstruction module for mobile robot localization. Finally, an environmental recognition strategy for welding mobile robot is developed in order to recognize the work environments efficiently. The design of the sensor system, the algorithm for sensing the partially structured environment with plane segments, and the recognition strategy and tactics for sensing the work environment are described and discussed with a series of experiments in detail.