• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.146-151
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• 2009

It is known that muzzle flash can be generated by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. A hugh muzzle flash, which is a characteristic of small arms with short barrel length, disturbs a shooter in aiming at the target at night by making the shooter blind for a while and endangers the shooter's life by revealing firing position to enemies. In addition, the heat of muzzle flash can deteriorate the performance of thermal sights, which are attached to small arms for effective night combat. In this paper, flash suppressors of different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length and the performance of each flash suppressor to reduce the muzzle flash was compared by on-site test firing. Through the test firing, a highly efficient design of flash suppressor for reducing the muzzle flash was identified. The result of the paper can be referred when designing flash suppressors for small arms with short barrel length.

• Archives of Plastic Surgery
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• v.49 no.2
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• pp.240-252
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• 2022

Rather than just another "review," this is intended to be an "overview" of the entire subject of the medial sural artery perforator (MSAP) flap as has been presented in the reconstructive literature from its inception in 2001 until the present, with any exceptions not purposefully overlooked. Unfortunately, the pertinent anatomy of the MSAP flap is always anomalous like most other perforator flaps, and perhaps even more variable. No schematic exists to facilitate the identification of a dominant musculocutaneous perforator about which to design the flap, so some adjunctive technology may be highly valuable for this task. However, if a relatively thin free flap is desirable for a small or moderate sized defect that requires a long pedicle with larger caliber vessels, the MSAP flap deserves consideration. Indeed, for many, this has replaced the radial forearm flap such as for partial tongue reconstruction. Most consider the donor site deformity, even if only a conspicuous scar on the calf, to be a contraindication. Yet certainly if used as a local flap for the knee, popliteal fossa, or proximal leg, or as a free flap for the ipsilateral lower extremity where a significant recipient site deformity already exists, can anyone really object that this is not a legitimate indication? As with any perforator flap, advantages and disadvantages exist, which must be carefully perused before a decision to use the MSAP flap is made. Perhaps not a "workhorse" flap for general use throughout the body, the MSAP flap in general may often be a valuable alternative.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.131-148
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• 2015

The purpose of this study is to analyze and compare the heat transfer efficiency of using copper pipe, stainless pipe and traditional PE pipe commonly used for geothermal heat exchanger, with aims at seeking improved methods. In addition, the varying efficiency of heat transfer from ground heat and groundwater heat was assessed and its applicability was discussed. Design parameters for empirical field study were derived by controlling flow rate, velocity and caliber of pipes of the heat exchanger after the thermal efficiency of the heat exchanger material was evaluated. The heat exchange efficiency and effective thermal conductivity were measured with changing pattern through field thermal efficiency and thermal response test. Experimental results show that the metal material showed higher heat transfer efficiency than the PE pipe. Although the heat transfer efficiency was not high with the increase of the pipe diameter in the flow rate, it was high with the increase of the pipe diameter in the velocity.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.324-333
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• 2012

The conventional medium and large caliber gun, in general, utilize the hydro-pneumatic recoil mechanism to control the firing impulse and to return to the battery position. However, this kind of mechanism may cause the problems like the leakages and the property changes in oil and gas due to the temperature variations between low and high temperatures. Accordingly, the friction spring mechanism has recently been researched as an alternative system. The friction spring mechanism consists of a set of closed inner and outer rings with the concentric tapered contact surfaces assembled in the columnar form, and can only be used under the compression load. When the spring column is axially loaded, the tapered surfaces become overlapped, causing the outer rings to expand while the inner rings are being contracted in diameter allowing an axial displacement. Because of friction between tapered contact surfaces, much higher spring stiffness is obtained on the stroke at the increase in load than the stroke at the decrease. In this paper, the dynamic equations regarding the friction spring system and the design approach have been investigated. It is also tried for a dynamic model representing the recoil motion and the friction spring forces. And the model has been proved from firing test using a gun system with friction springs. All the results show that the recoil mechanism using friction springs can substitute for the classic hydro-pneumatic recoil system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.307-316
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• 2004

This study examined the cause of the wrinkle defect which is frequently encountered in wire rod rolling of low carbon steel$(C0.08\~0.13wt.\%)$. Even a small defect on the surface of rolled bars can easily develop into fatal cracks during cold heading process of low carbon steel, and it is therefore necessary to minimize inherent defects on the surface of hot rolled bars. Hot rolling process of low carbon steel was analyzed to identify the cause of the wrinkle defect in conjunction with FE analysis. The integrated analysis revealed that the wrinkle defect initiated in the first stage of rolling, and it was at the billet edge where severe deformation and drastic temperature drop were present. To elucidate the micro-mechanical mechanism of the wrinkle defect, hot compression tests were carried out at various temperatures and strain rates using Gleeble-3800. The surface profile of the each other compressed specimens was compared, and rough surface lines were observed at relatively low temperatures. Those surface defects can develop into wrinkles during multi-pass rolling. To control the wrinkle defect in rolling, it is necessary to design an adequate caliber which can minimize the loss of ductility, and thereby prevent flow localization. To use the result of this study fur other steels, the quantitative measure of the wrinkle defect and flow localization parameter should be proposed.

• Fire Science and Engineering
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• v.21 no.3
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• pp.69-77
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• 2007

Our country automatic wet pipe sprinkler system of hydraulically designed system has not deviated from the pipe regulation process, therefore we face limitations when using an independent method to hydraulically designed system. Therefore. after reviewing a developed country's methods using the drainage-density concept, we found it necessary for our country to introduce the drainage-density concept. Currently, under the National Fire Safety Codes(NFSC), this does not solve the problem and the limitation of hydraulically designed system because different problems arise depending on where the head was installed. To make improvements, first, such as the developed country, overcome the difference by introducing the drainage-density concept to determine the amount of drainage. Second, by using diverse head caliber and decreasing the limits on the amounts of distribution, we can expect a leveling off of the drainage density. Third, using the increase of hydraulically designed system through the application of the rule to hydraulically designed system, finally, development to performance based fire protection design.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.979-985
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• 2011

This paper includes that there are results of designing the flash hider and analyzing fluid dynamics of a front area of the barrel to shorten the length of small arms. Generally, the muzzle flash can be generated out of the barrel by the reaction between the oxygen in the air and unburned gunpowder contained in the propellant gas if a barrel is not long enough to burn gunpowder fully inside of the barrel. Though, the hugh muzzle flash, which is a characteristic of small arms with short barrel length, caused a soldier to aim at the target at night by making the soldier blind for a while and endangers his life by revealing firing position to enemies. Besides, the heat of muzzle flash can weaken the performance of thermal sights, which are attached to small arms for night battlefield. In this paper, flash hiders with several different shapes were designed for a newly developed 5.56mm caliber rifle with short barrel length. The performance of each flash hider to reduce the muzzle flash was compared theoretically and experimentally. Through the authorized test procedure, a highly efficient design of flash hider for reducing the muzzle flash was identified. The result of the paper can be helpful when designing flash hiders for small arms with short barrel length.

• Journal of Korea Trade
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• v.25 no.2
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• pp.58-74
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• 2021

Purpose - This paper research on the embodied carbon emission in Sino-Korea trade. It calculates and analyzes the carbon emission coefficient and specific carbon emissions in Sino-Korea trade from 2005 to 2014. Design/methodology - This paper conducted an empirical analysis for embodied carbon emission in Sino-Korea trade during the years 2005-2014, using a multi-region input-output model. First, direct and complete CO2 emission coefficient of the two countries were calculated and compared. On this basis, combined with the world input-output table, the annual import and export volume and sector volume of embodied carbon emission are determined. Then through the comparative analysis of the empirical results, the reasons for the carbon imbalance in Sino-Korea trade are clarified, and the corresponding suggestions are put forward according to the environmental protection policies being implemented by the two countries. Findings - The results show that South Korea is in the state of net trade export and net embodied carbon import. The carbon emission coefficient of most sectors in South Korea is lower than that of China. However, the reduction of carbon emission coefficient in China is significantly faster than that in South Korea in this decade. The change of Korea's complete CO2 emission coefficient shows that policy factors have a great impact on environmental protection. The proportion of intra industry trade between China and South Korea is relatively large and concentrated in mechanical and electrical products, chemical products, etc. These sectors generally have large carbon emissions, which need to be noticed by both countries. Originality/value - To the best knowledge of the authors, this study is the first attempt to research the embodied carbon emission of ten consecutive years in Sino-Korea Trade. In addition, In this paper, some mathematical methods are used to overcome the error problem caused by different statistical caliber in different databases. Finally, the accurate measurement of carbon level in bilateral trade will provide some reference for trade development and environmental protection.

• Journal of Distribution Science
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• v.12 no.12
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• pp.55-63
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• 2014

Purpose - In urban regeneration projects, considerations for rejuvenating traditional public markets are becoming increasingly important. That is because the traditional market is not just a commercial space but also a living center for local people's existence. Cultural contents like these are invaluable assets in the contemporary economy. However, traditional markets are gradually declining because of changes in distribution systems and consumer lifestyles. New distribution systems such as modern distribution markets, home shopping, and online shopping malls made traditional markets less competitive. Further, traditional markets have not been able to adapt to the changing consumption styles of younger generations. Some say that it is a natural phenomenon that cannot be stopped. However, traditional markets are not just another distribution system but also a valuable resource that encapsulates the local people's tradition and history. Thus, a revitalization strategy for traditional public markets has become an urgent task in contemporary urban regeneration projects. This study aimed to find ways to activate traditional public markets by making it a community landmark based on visual merchandising perspectives. Research design and methodology - This study focused on analyzing Granville Island (Vancouver, Canada) as a role-model project for rejuvenating the traditional market. It investigated Granville Island both with walk-through evaluation and literature reviews. Results - We found that it has been developed not only to improve visual aspects, but also to promote cultural contents with high value added. For example, the developers maintained the visual elements that tell the original history of the site as an industrial factory. The renewal project had a balance between improving the outer look and creating attractive contents. The following are the merits of Granville Island that Korean traditional markets should note. First, they kept the whole area clean and hygienic. Second, merchants are well educated, business-savvy, and consumer-oriented. Third, the area's total environmental designs were done by professionals of a high caliber. Fourth, the city government and the merchants'association were collaborating well in their efforts to accommodate the changing needs of consumers. Conclusions - This study made the following suggestions as a conclusion. First, it will be a very powerful tool to rejuvenate the traditional market if we can discover unique cultural resources and develop them as cultural products, experiences, and events. Consumers of the 21st century have a strong tendency to consume not only material products, but also the experiences and memories attached to them. Second, in order to maintain the unique characteristics of traditional markets, fostering the viability of the merchants' association and local residents' society would be essential. Third, it is necessary to make the traditional market into a cultural place not only for the shopping patronage of local residents, but also for attracting tourists to increase sales. Finally, professional management and design approaches are needed in order to make the traditional market a pleasant space from a visual merchandising standpoint.

• KOMUNHWA
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• no.69
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• pp.91-111
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• 2007

This paper deals with the cultural and ideoligical background of the landscape designs on Joseon blue and white porcelains in the late Joseon period, and involves the government painters in the official kiln. Dongjeongchuwol-design (동정추월문), painted the full-moon night scene of Dongjeong lake on Jeseon blue and white porcelains, was in fashion in the late Joseon period. It didn't reflected the entirely realistic subject comparing to the painting circles at that time, but the principle and aesthetic appreciation of Royal family who leaded the official kiln. And Sansuinmul-design (산수인물화). painted the man of great caliber in the ancient history with mountain scenery, was similar to the painting manuals such as Gossihwabo (고씨화보) and Dangsihwabo (당시화보). It was a counterpart of Dongjeonchuwol-design on Joseon blue and white porcelains in the late Joseon period. These designs were painted into ogival-shaped frame (릉화창) on the blue and white porcelains in most cases, and adjusted to shape of porcelain. The landscape designs on Joseon blue and white porcelains became stereotyped, involving subjects of folk painting in the late 18th Century and the early 19th Century. This essay will be just a start to research into the landscape designs on blue and white porcelains in the late Joseon period, even though we seldom find works providing strict chronology among some works to the public.