• Journal of IKEEE
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• v.22 no.4
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• pp.1068-1072
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• 2018

In underwater communications, there are many challenges due to energy limitations, long propagation delay, low data rate, and high power loss, unlike terrestrial RF communications. Especially, the propagation delay of underwater acoustic channel is five orders of magnitude higher than in electro-magnetic terrestrial channels due to the low speed of sound(1,500m/s). Thus, the MAC protocols for terrestrial communications are not suitable for underwater network. In this paper, we studied the considerations for MAC protocol in underwater acoustic channel. Here, we concentrated on CSMA based MAC protocols. From the results, we confirmed that the number of control packets has an important effect on the performance in underwater environment. These results would be useful in designing MAC protocols for underwater acoustic communications.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.457-469
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• 2012

Bedform data at 4 shallow zones in the Yellow Sea where waves as well as tidal range are high and bed material is relatively coarse were collected and analyzed here. Water depths in the study area where the bedform data were collected are 10 ~ 65 meters, and ripple lengths well developed are between 6 ~ 13 meters. Existing empirical formula for prediction of ripple length as for coexistence of waves and currents include Khelifa and Ouellet(2000) and Soulsby(2005), both of which have been based on laboratory measurements, or field measurements at different physical environment from the Yellow Sea with respect to tidal range, wave strength, and bed material. New scaling factors are proposed here for better prediction of the ripple length on coastal zone in the Yellow Sea.

• Journal of Information Technology and Architecture
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• v.9 no.4
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• pp.433-442
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• 2012

This paper focuses on developing a smartphone-based mobile office system for a logistics company in Korea using HTML5. Mobile office is smart working environment of working out of a company office using mobile devices such as smartphones and portable computers which are connected to the company servers via WiFi or 3G/4G. Recently many companies are introducing mobile office information systems with the smartphone wave, but they are having difficulties in maintaining and updating their systems due to the transformative mobile application platform. Therefore, we need a platform-independent implementation tools for the mobile office application and HTML5 is one of the solution tools. In this paper, we develop mobile and web applications applicable to all kinds of mobile devices such as iOS, android and windows mobile etc using HTML5. The proposed mobile office system consists of groupware, marketing management, reporting module and transportation management system.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.254-258
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• 2019

To protect healthy and beautiful hair, the hair protection effect was tested by adding an aloe extract from the hair solution. The treatment groups were grouped into four categories: Group II (Famma Treatment Only), Group III (Oxidase+aloe), Group IV (Reduce+aloe), and Group V (Oxidase+aloe, Release+aloe). The test hair is collected from women's hair in their 20s, 30s and 40s who have not undergone chemical treatment such as permanent and dying for one year and use 100% aloe stock solution. In order to evaluate hair thickness, cuticles, tensile strength, elongation and formation rate, the experiment environment was 28.9 degrees and 72% humidity. All statistical tests were done at 5% significant level. Cuticle, elongation, and formation rate were significantly improved (P<.05) and cuticle was best in group V, elongation was group III. In conclusion, aloe added to perm treatment were effective in improving cuticle, elongation rate, and formation of hair.

• Industry Promotion Research
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• v.6 no.4
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• pp.11-21
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• 2021

This study tried to analyze the factors of corporate growth potential of CJ E&M, a representative company in the content industry. First, in order to analyze CJ E&M's growth Engine, Michael Porter's diamond model was used to review key factors, and then, based on the 4P model, directions for future corporate growth were suggested. As a Result, Factors behind corporate growth included "Media content of various genres" and "recruitment of star-class human resources", in terms of Production Conditions, and "Gratification Chinese market demand" in terms of Demand Conditions. In addition, "Korean wave industry aiming at K-Culture" in terms of Related Industry and "Two track strategy: global·glocal strategy" and "Media commerce strategy" in terms of business environment: strategy, structure, and competition was able to analyze. For the direction of development, there are "various products through collaboration of affiliated companies" in terms of Product and "TVING Benchmarked Netflix" in terms of Price. In addition, "global expansion through OTT platform TVING" in terms of place and "challenge marketing utilizing the Tiktok platform" in terms of promotion must be carried out.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.28-41
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• 2023

The objective of the study was to develop an Urban Windway Forest Creation Planning Technique for the Improvement of the Urban Environment using the case of Daejeon Metropolitan City. Through a spatial analysis of fine dust and heat waves, a basin zone, in which the concentration was relatively serious, was derived, and an area with the potential of cold air flow was selected as the target area for the windway forest development by analyzing the climate and winds in the relevant zone. Extreme fine dust areas included the areas of the Daejeon Industrial Complex Regeneration Business District in Daedeok-gu and Daedeok Techno Valley in Yuseong-gu. Heat wave areas included the areas of Daedeok industrial Complex in Moksang-dong, the Daejeon Industrial Complex Regeneration Business District in Daehwa-dong, and the high-density residential area in Ojeong-dong. As a result of measuring the wind speeds in Daejeon with an Automatic Weather System, the average wind speeds during the day and night were 0.1 to 1.7 m/s,, respectively. So, a plan of for a windway forest that smoothly induces the movement of cold air formed in outer forests at night is required. The fine dust/heat wave intensive management zones of Daejeon Metropolitan City were Daejeoncheon, Yudeungcheon, Gapcheon-Yudeungcheon, and Gapcheon. The windway forest formation plan case involved the old city center of Daejeon Metropolitan City among the four zones, the Gapcheon-Yudeungcheon area, in which the windway formation effect was presumed to be high. The Gapcheon-Yudeungcheon area is a downtown area that benefits from the cold and fresh air generated on Mt. Gyejok and Mt. Wuseong, which are outer forests. Accordingly, the windway forest was planned to spread the cold air to the city center by connecting the cold air generated in the Seosa-myeon forest of Mt. Gyejok and the Namsa-myeon forest of Mt. Wuseong through Gapcheon, Yudeungcheon, and street forests. After selecting the target area for the wind ventilation forest, a climate map and wind formation function evaluation map were prepared for the area, the status of variation wind profiles (night), the status of fine dust generation, and the surface temperature distribution status were grasped in detail. The wind ventilation forest planning concept and detailed target sites by type were identified through this. In addition, a detailed action plan was established according to the direction of creation and setting of the direction of creation for each type of wind ventilation forest.

• Transactions of the KSME C: Technology and Education
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• v.4 no.1
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• pp.63-71
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• 2016

Although mechatronics education in a mechanical engineering curriculum is recently recognized as important, its experimental education has been done generally in the laboratory equipped with all the apparatus and could not be done at home by students. This paper introduces experimental educations on mechatronics, e.g., digital logic circuits, 7-segment LED drive, square wave generation, microcontroller programming using assembly and C languages, timer interrupt, and step motor drive using a small 5 V power supply, a breadboard, various electronic and electric components, a microcontroller and its programmer, a step motor, and a student's PC. In the developed mechatronics course, experimental educations are scheduled in parallel with content's lectures together, and cheap and economic experimental environment is prepared for students in which students can easily practice experimental works in advance or later at home by themselves.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.183-194
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• 2010

A suitability analysis for marine afforestation was carried out on physical items based on slop rate, bottom sediment, light intensity, velocity, and wave at north Geomoon waters in Korea. The data from each physical item were changed to a GSDM (Gridded Spatial Distribution Map) using Kriging interpolation. A GSDM grid includes information, and each grid was given a SI (suitability index) of 3 grades(SI of first suitability was 100, SI of second suitability was 50, and non-suitability had no SI). According to the analysis results of all overlaid GSDM, first suitability had 500 SI, and suitability area was 0.25ha. Second and third suitability had 400~450 SI, and suitability area was 2.36ha, 1.80ha, respectively. Therefore, the results suggest that reefs installed for marine afforestation should be anti-slip types against steep slope, and the target species need to include algae with low compensation light intensity in second and third suitability.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.4
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• pp.141-151
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• 2017

Nowadays, It is undeniable that the threat of network security is growing as time flows due to worldwide development of wire/wireless, various Internet platform and sophisticated hacking techniques. The amount of traffics that Network security solution has to handle is increasing and recently many occurrence of explosive traffic attacks from PulseWave are being observed which has many similar characteristics to New DDos. Medium and small sized firms abroad have developed and distributed Snort and Suricata that are based on open-source Intrusion Detection System(IDS) / Intrusion Prevention System (IPS). The goal of this study is to compare between Windows7 by applying suicata 4.0.0 32bit version and Ubuntu 16.04.3 LTS by applying suicata 4.0.0 version which is an open source Intrusion Detection System / Intrusion Protection System that uses multi threads method. This experiment's environment was set as followed C1100 server model of Dell, Intel Xeon CPU L5520 2.27GHz*2 with 8 cores and 16 threads, 72GB of RAM, Samsung SSD 250GB*4 of HDD which was set on RAID0. According to the result, Suricata in Ubuntu is superior to Suricata in Windows7 in performance and this result indicates that Ubuntu's performance is far advanced than Windows7. This meaningful result is derived because Ubuntu that applied Suricata used multi core CPU and RAM more effectively.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.247-260
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• 2016

Sensor networks have been used in many applications such as smart home, smart factory, etc. based on sensor data. Sensor networks can change system requirements and architectures depending on their application areas. Currently, sensor network application cases in ocean environments are very rare because the ocean environments have much difficult accessibility more poor conditions, higher wave heights, more frogs, much heavier salinity, etc., compared with ground environments. In this paper, we propose the requirements, architecture and design of a sensor network system for the littoral sea cage culture monitoring and we also introduce its operation results through the development. The developed system based on our research provides users with functionalities to extract, monitor, and manage underwater environmental conditions suitable to littoral sea cage culturing of fishes.