• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.946-952
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• 2013

Large scale fire tests were conducted to develop water mist nozzles as a component of fixed water- based fire fighting systems for Ro-Ro spaces and special category spaces. Fire scenarios for this system consist of two cases which are for cargo fire in a simulated truck and for passenger vehicle fire, and each case has 3 different tests according to the position between fixed water mist nozzles and fire source. Every experiment proceeded for 30 minutes and acceptance criteria were based on gas temperature, fuel package's damage and ignition of targets. This study primarily dealt with the experimental results of cargo fire and focused on fire suppression capability in accordance with discharge pressure, flow rate and flow characteristics like swirl and penetration of the developed water mist nozzles. It appeared that low pressure water mist nozzles with about 40 L/min were able to control fire occurred in Ro-Ro spaces.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.82-93
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• 2002

The effects of the interaction between the flow and temperature field and a boundary layer due to a variety of the height of a vortex generator are experimentally investigated. The test facility consists of a boundary-layer wind tunnel with the vortex generator protruding from the bottom surface. In order to control the strength of the longitudinal vortices, the angle of attack and the spacing distance of the vortex generator are 20 degree and 40 mm, respectively. The height of the vortex generator (H) is 15 mm, 20 mm and 30 mm and the cord length of it is 50 mm. Three-component mean velocity measurements are made using a 5-hole probe system and the surface temperature distribution is measured by the hue capturing method using thermochromatic liquid crystals. By using the method mentioned above, the following conclusions are obtained from the present experiment. The boundary layer is thinned in the downwash region where the strong downflow and the lateral outflow of the boundary layer fluid occur and thickened in the upwash re,3ion where the longitudinal vortex sweeps low momentum fluid away from the bottom surface. In case that the height of the vortex generator increases, the averaged circulation and the maximum vorticity of the vortex pair decrease. The contours of the non-dimensional temperature show the similar trends fur all the cases (H=15 mm, 20 mm and 30 mm). The peak augmentation of the distribution of the local non-dimensional temperature occurs in the downwash region near the point of minimum boundary-layer thickness.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.199-211
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• 2009

Recent advancements in wireless networks have enabled support for mobile applications to transfer data over heterogeneous wireless paths in parallel using data striping technique [2]. Traditionally, high performance data transfer requires tuning of multiple TCP sockets, at sender's end, based on bandwidth delay product (BDP). Moreover, traditional techniques like Automatic TCP Buffer Tuning (ATBT), which balance memory and fulfill network demand, is designed for wired infrastructure assuming single flow on a single socket. Hence, in this paper we propose a buffer tuning technique at senders end designed to ensure high performance data transfer by striping data at transport layer across heterogeneous wireless paths. Our mechanism has the capability to become a resource management system for transport layer connections running on multi-homed mobile host supporting features for wireless link i.e. mobility, bandwidth fluctuations, link level losses. We show that our proposed mechanism performs better than ATBT, in efficiently utilizing memory and achieving aggregate throughput.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.434-443
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.665-672
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• 2016

This study is conducted to investigate the effect of phase change materials (PCM) on hydration heat and strength characteristics of cement mortar. Two types of Barium and Strontium-based PCMs were used in this study and the addition ratio of each PCM to the cement mortar ranged from 1% to 5% by cement weight. Flow test, semi-adiabatic temperature rise test, compressive strength and flexural strength test were carried out to examine the PCM effect on heat and mechanical properties of cement mortar. Test results indicated that PCMs used in this study were effective to control hydration heat of cement mortar, and Barium-based PCM slightly reduce flow value. The compressive and flexural strength of cement mortar with PCM decreased with increasing the adding mount of PCM. The prediction model for compressive strength of cement mortar with different addition levels of PCMs are suggested in this study.

• Journal of Navigation and Port Research
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• v.34 no.5
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• pp.325-330
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• 2010

An open water rudder test was carried out to figure out the flow characteristics around a twin rudder at $Re=1.5{\times}10^4$. In the analysis, the unique characteristics of a twin rudder, which affects rudder forces, were explained. The analysis includes varying angles of attack from 10 to 30 degrees. In this paper, the measured results have been compared with each other to predict the performance characteristics of a twin rudder's 2-dimensional section by 2-frame grey level cross correlation PIV method. The length L=0.75C between upper and lower rudders could be defined as the critical length.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.286-292
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• 2017

The Coastal VTS will be continuously constructed to prevent marine traffic accidents in the coastal waters of the Republic of Korea. In order to provide the best traffic information service to the ship operator, it is important to understand the navigation risk factor. In this study, we analyzed the navigational hazards of Gunsan coastal area where the coastal VTS will be constructed until 2020. For this purpose, major traffic flows of merchant ships and density of vessels engaged in fishing were analyzed. This study was conducted by Automatic Identification System (AIS) and Vessel Pass (V-PASS) data. The grid intervals are 10 minute ${\times}$ 10 minute (latitude ${\times}$ longitude) based on the section of the sea. A total of 30 sections were analyzed by constructing a grid. As a result of the analysis, the major traffic flows of the merchant vessels in the coastal area of Gunsan were surveyed from north to south toward Incheon, Pyeongtaek, Daesan, Yeosu, Pusan and Ulsan, and from east to west in the port of Gunsan Port, 173-3, 173-6, 173-8, 183-2, 183-5, 183-8, 183-3, 184-1 and 184-2. As a result of the study, the fishing boats in Gunsan coastal area mainly operated in spring and autumn. On the other hand, the main traffic flow of merchant ships and the distribution of fishing vessels continue to overlap from March to June, so special attention should be paid to the control during this period.

• Korean journal of food and cookery science
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• v.24 no.5
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• pp.652-664
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• 2008

In this study, a Hazard Analysis Critical Control Point (HACCP) plan was developed for the sanitary mass production of commercial Korean rice cake products (Gaepidduk, Injulmi, and Julpyon). The microbiological properties of manufacturing flow were evaluated in order to develop the HACCP Plan. The moisture contents of the rice cakes ranged between 36.2${\sim}$55.3%, whereas the water activity of all samples ranged between 0.954${\sim}$1.0. Microorganisms testing was conducted during various phases of the product flow of Korean rice cake preparation, and included assessments of food equipment, work environment, and cooking employees on a small scale. During the manufacture of Injulmi, Julpyon and Gaepidduk, CCPs were purchasing & storage, steaming and cooling, molding, and holding in the A and B manufactories. At the critical limit of CCPs, storage was conducted below at $5^{\circ}C$ in soybean powder, oil, and paste with redbeans. The steaming process was conducted above at $99^{\circ}C$ for 40 min. Cooling and holding processes were conducted for 2 hours below at $15^{\circ}C$. The molding process included sanitary education for foodhandlers and training for operators. Thus, certain prerequisite programs had to be implemented prior to the implementation of the HACCP system. High levels of bacterial contamination were detected in the aprons worn to work by some employees. Additionally, periodic sanitary education for foodhandlers and training for operators or managers was required. Cross contamination by materials was expected at the place where materials were processed or stored.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.2964-2985
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• 2019

Global data center IP traffic is expected to reach 20.6 zettabytes (ZB) by the end of 2021. Intra-data center networks (Intra-DCN) will account for 71.5% of the data center traffic flow and will be the largest portion of the traffic. The understanding of traffic distribution in IntraDCN is still sketchy. It causes significant amount of bandwidth to go unutilized, and creates avoidable choke points. Conventional transport protocols such as Optical Packet Switching (OPS) and Optical Burst Switching (OBS) allow a one-sided view of the traffic flow in the network. This therefore causes disjointed and uncoordinated decision-making at each node. For effective resource planning, there is the need to consider joining the distributed with centralized management which anticipates the system's needs and regulates the entire network. Methods derived from Kalman filters have proved effective in planning road networks. Considering the network available bandwidth as data transport highways, we propose an intelligent enhanced SDN concept applied to OBS architecture. A management plane (MP) is added to conventional control (CP) and data planes (DP). The MP assembles the traffic spatio-temporal parameters from ingress nodes, uses Kalman filtering prediction-based algorithm to estimate traffic demand. Prior to packets arrival at edges nodes, it regularly forwards updates of resources allocation to CPs. Simulations were done on a hybrid scheme (1+1) and on the centralized OBS. The results demonstrated that the proposition decreases the packet loss ratio. It also improves network latency and throughput-up to 84 and 51%, respectively, versus the traditional scheme.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.259-268
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• 2018

The purpose of this study is to propose a training method customized to the level of cognitive abilities to increase users' interest and engagement while using cognitive function training contents. The level of cognitive ability of the users was based on the clustering based on the users' information and Mini-Mental Statue Examination-Korea Child test score using the K-means algorithm applied collaborative filtering. The results were applied to the integrated cognitive function training system, and the contents order and difficulty level of the cognitive function training area were recommended to the user's cognitive ability level. Particularly, the contents difficulty control was designed to give a high immersion feeling by applying the 'flow theory' method that users can repeatedly feel tension and comfort. In conclusion, the user-customized cognitive function training method proposed in this paper can be expected to be more effective and rehabilitative results than existing therapists' subjective setting of contents order and difficulty level.