• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.468-475
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• 2019

An end-line flame arrester allows free venting in combination with flame protection for vertical vent applications. End-line flame arresters are employed in various fields, especially in shipping. In flame arresters, springs are essential parts because the spring load and the spring's elasticity determine the hood opening moment. In addition, the spring has to work under a high-temperature condition because of the burning gas flame. Therefore, it is necessary to analyze the mechanical load and elasticity of the spring when the flame starts to appear. Based on simulations of the working process of a specific end-line flame arrester, a thermal and structural analysis of the spring is performed. A three-dimensional model of a burned spring is built using computational fluid dynamics (CFD) simulation. Results of the CFD analysis are input into a finite element method simulation to analyze the spring structure. The research team focused on three cases of spring loads: 43, 93, and 56 kg, correspondingly, at 150 mm of spring deflection. Consequently, the spring load was reduced by 10 kg after 5 min under a $1,000^{\circ}C$ heat condition. The simulation results can be used to predict and estimate the spring's load and elasticity at the burning time variation. Moreover, the obtained outcome can provide the industry with references to optimize the design of the spring as well as that of the flame arrester.

• Korean Journal of Heritage: History & Science
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• v.46 no.4
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• pp.24-47
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• 2013

This study focused on the constructional concepts, landscape design techniques and changes made of the Sandan(山壇) area in the rear garden of Changdeokgung Palace based on the spatial organization of the zone. The results of this study are as below. Constructional layers that have been maintained throughout the centuries from King Injo(仁祖), King Sukjong(肅宗), King Sunjo(純祖), the Japanese colonial period to the present, were found in the Sandan area. The Sandan area, which was developed with the establishment of Chuiseungjeong(取勝亭) during the ruling of King Injo(仁祖), was created as a resting place for the King, and its usage continued until King Sukjong(肅宗) built Nakminjeong(樂民亭). However, the whole area was reorganized to host ritual ceremonies, where ancestral rites were performed for the mountain gods, after Sandan and Baekunsa(白雲社) were built during King Gojong's reign, before the drawing of 'Painting of Eastern Palaces(東闕圖).' The architectural component used then appears to have been designed to serve ancestral ritual formalities for the god of land, or to satisfy the religious desires of the royal family not fulfilled by Confucian courtesy. These are characteristics that define the Sandan area. Meanwhile, the analysis of the ground plan of the Changdeokgung Palace revealed that the Sandan had been maintained until the Japanese colonial era, but was removed sometime after liberation. The area underwent extensive reform in the early 1970s, when the whole area was developed into a tourist destination called Bingcheon(氷泉). Then, a new road that runs through Bingcheon was laid, and the present condition reflects the construction result of the time. An interview with a person who had taken part in the repair work in the 1970s confirmed that the construction work at the time had the goal of establishing two drainage systems for drinking water and copied the Okryuchon(玉流川) well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.426-431
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• 2019

In this study, we report the effect of pre-treatment of alpha-$Ga_2O_3$ grown on a sapphire substrate by halide vapor phase epitaxy (HVPE). During the pre-treatment process, 10 sccm of GaCl gas was injected to the sapphire substrate at $470^{\circ}C$. The surface morphologies of the alpha-$Ga_2O_3$ layers grown with various pre-treatment time (3, 5, and 10 min) were flat and crack-free. The transmittance of the alpha-$Ga_2O_3$ epi-layers was measured to analyze their optical properties. The transmittance was over 80% within the range of visible light. The strain in the alpha-$Ga_2O_3$ grown with a pre-treat 5 min was measured, and was found to be close to the theoretical XRD peak position. This can be explained by the reduction of strain having caused a lattice mismatch between the alpha-$Ga_2O_3$ layer and sapphire substrate. The calculated dislocation density of the screw and edge were $2.5{\times}10^5cm^{-2}$ and $8.8{\times}10^9cm^{-2}$, respectively.

• Korean Journal of Heritage: History & Science
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• v.45 no.4
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• pp.22-37
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• 2012

Storage facility of the pre-historic Korea is classified into the subterranean, ground and overground types. The rectangular-shaped subterranean Storage facilities have been identified in the Pungnaptoseong, the Gong mountain fortress site and the Gwanbukri site. Feature no. 196 at Gyeongdang District in Pungnaptoseong yielded a large quantity of glazed potteries, and a wooden storage at the Gwanbukri site contained a large amount of fruit seeds. These storage facilities might be functioned as the warehouse for the highest group rather than the storage for the emergency such as war and flooding and stipend of government officials. This article subdivided into "state storage" on the concept of the former that "royal storage" on the concept of the latter. If it look on the state storage at large, this include the royal storage too. But it subdivided to help article understand because Baekjae changed from state storage to royal storage by change and specialization of system after 4th. The reason why the diversification of storage pits was closely related to the unification of local polities and the concentration of political power in the state-level. Therefore, it might reflect the political circumstances the ruling elites attempted to heighten their authority in terms of the organizing tax collecting system. And divided the time of storage is confirmed separative storage pits in the suburbs of capital city. There is hight probability of top local polities or nation that have possessional a role. This is to cover on frequent war in the Three States. On the other hand, state storage is located around ancent road that linked castle gate that is divided into center and periphery depending on function and position of storage. Center is located royal storage focusing in the presumed royal palace that periphery is located state storage to provide service to the public. It is presumed that located with the government office.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.8
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• pp.191-200
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• 2019

In an Ad-hoc network, a method of time synchronizing all the nodes in a network centering on one reference node can be used. A representative algorithm based on a reference node is Flooding Time Synchronization Protocol (FTSP). In the process of sending and receiving messages, predictable and unpredictable delays occur, which should be removed because it hinders accurate time synchronization. In multi-hop communications, hop delays occur when a packet traverses a number of hops. These hop delays significantly degrade the synchronization performance among nodes. Therefore, we need to find a method to reduce these hop delays and increase synchronization performance. In the FTSP scheme, hop delays can be greatly increased depending on the position of a reference node. In addition, in FTSP, a node with the smallest node ID is elected as a reference node, hence, the position of a reference node is actually arbitrarily determined. In this paper, we propose an optimal reference node election algorithm to reduce hop delays, and compare the performance of the proposed scheme with FTSP using the network simulator OPNET. In addition, we verify that the proposed scheme has an improved synchronization performance, which is robust to topology changes.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.137-151
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• 2019

Geophysical exploration techniques are effective for monitoring changes in the ground condition around the excavation project to prevent subsidence risks during excavation work, therefore, improving analysis techniques is required for applying and supplementing various geophysical exploration technologies. In this study, a field-scale on-site test was conducted to detect possible ground subsidence hazards and areas of relaxation zone that may occur during excavation work and due to underground water level changes. In order to carry out the field test, a real-scale excavation test bed was constructed and the geophysical exploration methods, such as electrical resistivity survey and multi-channel analysis of surface wave (MASW) survey for urban sites condition, have researched for optimal geophysical exploration parameter, design and correlation analysis between the results by reviewing the validity of each individual geophysical exploration and modeling. The results of this study showed the impact of each geophysical exploration on the relaxation zone and, in particular, the location of the underground water surface and the effects of excavation were identified using electrical resistivity survey. Further research on modeling will be required, taking into account the effects of excavation and groundwater.

• Journal of the HCI Society of Korea
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• v.14 no.1
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• pp.5-13
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• 2019

SNS has been advanced from first to third generation by changing its service format in various ways. Nowadays, image-based SNS such as instagram and pinterest where users communicate via images has become popular as third generation service. Due to the fact that users communicate especially through images, image-based SNS utilizes images in different ways compared to other SNS. This study derived various characteristics of images in image-based SNS, and observed how users perceive each of them differently. Also, relationship between the characteristics and user satisfaction on image-based SNS is analyzed. The characteristics include 6 items; 'implicity', 'recordability', 'expressing identity', 'indirect experience', 'temporary amusement', and 'stimulating desire.' As a result of comparing user perception regarding those 6 characteristics, recordability and indirect experience were highly recognized than other characteristics. Also, according to users' age, motivation of using image-based SNS, and number of followers they have, users perceived each characteristic in different level. Finally, relationship between the characteristics and user satisfaction was analyzed, and the result showed that indirect experience had positive influence to user satisfaction. Regarding indirect experience, it was highly perceived by users and also had positive influence to their satisfaction, which means it is the most typical characteristic of image-based SNS.

• Journal of the HCI Society of Korea
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• v.14 no.1
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• pp.45-52
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• 2019

As the requirement of the in vehicle infotainment service increases, the role of the in vehicle display is also expected to rise. Particularly, center information display(CID) is expected to be actively utilized, and since the size and position of the display is anticipated to change, it is necessary to research based on the users' perspective. However, there are limited research studies that investigated the user's consciousness on the size and position of autonomous vehicle display. Herein, the purpose of this study is to identify and present the preference of the center information display's size and position on each levels of driving automation. For this, an experiment on the driving simulator was conducted using the think-aloud method. As a result, it was found that the horizontal display(12.5inch) on the top position was the most preferred in the second level of the driving automation. On level three, the participants significantly preferred the vertical display(17inches) compared to the second level. This study is significant since it conducted an empirical study which examines the user' preference of CID using a driving simulator for the autonomous vehicle.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.481-487
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• 2019

Based on the scan conditions and algorithms that are generally applied during examinations during head CT examinations, the results of dose reduction through the application of algorithm changes were investigated through experiments. As a result, the dose reduction effect was more meaningful for the change of perfusion than for the tube voltage, and the quality evaluation using the brain phantom was relatively less reduced when the dose was reduced after the application of the Bone algorithm, especially for the application of the Bone algorithm, and the deviation of the mean CT number or Pixel value was measured relatively significantly. In other words, the conditions under which dose was reduced and quality was maintained to reduce the patient's exposure dose and obtain images of the same quality were obtained with the application of the Smooth algorithm and the resulting values of 120 kVp, 160 mA. At this point, doses were reduced by about 28%, and the mean CT number or Pixel value was also measured with relatively little error. If the results are applied to patients who visit the hospital for examination or follow-up after applying various algorithms and follow up scan conditions, the results are considered to be very useful in reducing patient exposure dose.

• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.168-178
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• 2019

This study takes a close look at the recent success of independent documentaries to find its implications and a way to invigorate Korean documentary ecosystems. To this aim, this study performed in-depth interviews with independent documentary film makers and television documentary directors. Also, it analyzed the case of POV (Point Of View), which is television's longest-running showcase for independent documentary films in the USA. The results display that independent documentaries convey competitive edge of contents and expansion of distribution and funding through film industry systems, based on the producer systems, global distribution networks of overseas pitching and film festivals, marketing and audience strategy of film industry. Although this shows its molding of documentary industry ecosystems, there are great needs for various platforms other than film industrial outlet in order to make an advancement of the ecosystems under the digital environment. POV works on the basis of 'open sourcing' form when collaborating with independent film makers. Independent documentaries picked up by POV are aired on PBS, streamed via its online service, and distributed through community screenings; this three-outlet strategy makes POV a unique platform and has a relevance and feasibility to apply for Korean documentary ecosystems. Therefore, this study suggests to create a platform adopting POV system hoping that more studies and efforts would come for various and novel platform building so to make more advanced and invigorated ecosystems of Korean documentary.