• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.125-132
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• 2012

Urea-SCR system, which converts nitrogen oxides to nitrogen and water in the presence of a reducing agent, usually AdBlue urea solution, is known as one of the powerful NOx reduction systems for mobile as well as stationary applications. For its consistent and reliable operation in mobile applications, such various problems as transient injection, ammonia slip, and freezing in cold weather have to be resolved. In this work, therefore, numerical study on three-dimensional unsteady heating problems were analyzed to understand the melting and heat transfer characteristics such as urea liquid volume fraction, temperature profiles and generated natural convection behavior in urea solution by using the commercial software Fluent 6.3. After validating by comparing numerical and experimental data with pure gallium melting phenomena, numerical experiment for urea melting is conducted with three different coolant heating models named CH1, 2, and 3, respectively. Finally, it can be found that the CH3 model, in which more coolant is concentrated on the lower part of the urea tank, has relatively better melting capability than others in terms of urea quantity of $1{\ell}$ for start-up schedule.

• Analytical Science and Technology
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• v.14 no.1
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• pp.15-20
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• 2001

Photocatalytic $TiO_2$ films were prepared by anodic oxidation at 180 V and their structural difference caused by oxidation conditions was studies. The microstructure of $TiO_2$ films in $H_2SO_4$ and $H_2SO_4/H_2O_2$ solution was mixed type of rutile and anatase. However, the $TiO_2$ layer formed in $H_2SO_4/H_3PO_4$ and $H_2SO_4/H_3PO_4/H_2O_2$ mixture was mostly anatase type. All $TiO_2$ films prepared by anodic oxidation exhibited photocatalytic properties. The photocatalytic degradation of aniline blue was first order reaction with similar rate constants at all oxidative conditions examined in this work.

• The Journal of the Korea Contents Association
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• v.13 no.6
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• pp.116-124
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• 2013

This study aims to develop colored gemstone products based on the analysis of color preference. Colored gem stones were classified by their colors using Munsell's ten basic colors and the color preference of women consumers in their twenties was analyzed, in consideration of trend analysis and design image description analysis, which led to the direction of product development. The analysis of color preference seems to suggest that consumers preferred blue quartz, cahnite, spessartite garnet, the colors of which are rather less known to ordinary consumers, to the other more common kinds of gem stones. Through the analysis of the trends and adjectives to describe preferable design images, the current study has made it possible to explore the designs for the future development of colored jewelry products, which would satisfy the consumption value and individual tastes of the consumers. It is expected that the current study may contribute to the jewelry industries and designers as a basic data for developing colored gem stone products.

• Journal of the Korea Computer Industry Society
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• v.4 no.4
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• pp.547-552
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• 2003

In this thesis, interference phenomena of bluetooth networks requiring Security were minimized; strengthened security of piconet by assigning an identical PIN code to bluetooth devices, which was establishing a specific piconet during authentication stage. To establish a bluetooth piconet system. an unique ID was assigned to each bluetooth device, communication algorithms having different data formats between devices was designed, and an embedded hardware module using ARM processor and uCOS-II RTOS was implemented. About 30% of CPU efficiency in the module was increased by modifying functions including block parameters to work as nonblocking; by the increased efficiency of total piconet, the module could be used as an access point. The module could transmit maximum 10 frames of image and also audio signal by switching the packet effectively according to channel condition. By above-mentioned process, video, audio, and data could be well transmitted by the bluetooth managing program and the possibility of a commercial remote control system using bluetooth technology was suggested.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.9-17
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• 2017

In this paper, we propose a method to develop a multimeter which is used for measuring electric signals in industrial field by using battery and display of smart phone. Most of the multimeters that are linked to existing smartphones are connected to Bluetooth, which is inconvenient for battery use and low in measurement accuracy. To improve this, we developed smart multimeter that can supply power and data at the same time by USB OTG method which can be used by sharing the power of smartphone. We also developed a smart multimeter that can measure resistance, DC voltage, current, AC voltage and current. Developed an Android app with a button that displays measurement data and can select the type of electric signal to be measured, and tests whether the manufactured system is operating normally or not. Respectively.The results of this study confirm that it is possible to fabricate a smart meter that has equal or better performance compared to existing instruments and does not require a separate power source or display, and it is expected to be a reference for the development of various smart instruments in the future.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.77-83
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• 2002

The emergence of Bluetooth as a radio interface scheme has allowed electronic devices to be instantly interconnected as ad-hoc networks. These short range ad-hoc wireless networks are called piconets, operated in the unlicensed 2.45 GHz ISM(Industrial, Scientific, Medical) band where up to eight devices may be used to configure single or overlapping piconets. In this paper, we have simulated the PER(Packet Error Rate), the ratio of received packet and payload BER(Bit Error Rate) of piconet with packet types of Bluetooth ACL/SCO(Asynchronous Connection Less/Synchronous Connection Oriented) link over wireless ad-hoc environment. The Rayleigh fading effects are considered as channel model, and the simulation results are based on the baseband model of Bluetooth specification. From the simulation results, the PER and the throughput of Bluetooth piconet are sensibly affected by the packet type of ACL/SCO link.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.787-792
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• 2009

A number of very promising applications such as health monitoring and U-Health of ubiquitous techniques has attracted interest in recent years. Because it can observes the condition of patient from long distance using the equipment which combines with radio communication and medical monitoring system. If it is at emergency situation, it can disposes the condition of the patient. In this paper, we propose the new data format and the transmission communication system of combination medical information with the bluetooth. And we produce the on-board system which transmits the medical information. This system integrated the blood pressure and glucose monitor of personal medical equipment, and the medical information which obtained from on-board system acquires through the gateway with the bluetooth. Medical information is transmitted to the tele-monitor server by the wireline network. We evaluated the proposed system under the laboratory environment and confirmed the excellent performance of transmission of the medical information.

• KIISE Transactions on Computing Practices
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• v.22 no.6
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• pp.268-277
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• 2016

IoT (Internet of Things) technologies have largely contributed to our smart living environment. The smart parking system is one of the prominent services that IoT supports. To identify the parked vehicles, the previous parking system use special identifying devices, the RFID tags carried by the users, and the high quality camera to recognize the vehicle license numbers. However, the previous methods cause cost inefficiency and unfriendly usages. To address these problems, we propose a smart parking system based on ultrasonic sensors and Bluetooth communication. The proposed system decides the available slots by using the sensor motes located in the parking spaces. Also it recognizes the location of the parked vehicle using Bluetooth RSSI between a Smartphone and the sensor motes. In addition, based on these converging technologies, it can support the parked routes of vehicles for users. To evaluate the implemented smart parking system, we applied the RSSI transform equations and the recognition rate for parked vehicles. As a result, the accurate rate of transformed distances could be measured.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.109-114
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• 2006

Biodegradable poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles were developed for sustained delivery of water-soluble macromolecules. PLGA nanoparticles were fabricated by spontaneous emulsification solvent diffusion method generating negatively charged particles and heterogeneous size distribution. As a model drug, blue dextran was encapsulated in PLGA nanoparticles. In addition, nanoparticles were also prepared with varying ratio of poloxamer 188 (P188) and poloxamer 407 (P407), and coating with poly(vinyl alcohol) (PVA). Then, the particle size, zeta potential and encapsulation efficiency of nanoparticles containing blue dextran were studied. In vitro release of blue dextran from nanoparticles was also investigated. The surface and morphology of nanoparticles were characterized by scanning electron microscopy (SEM). In case of nanoparticles prepared with PLGA, P407, and different organic solvents, particle size was in the range of $230{\sim}320\;nm$ and zeta potentials of nanoparticles were negative. The SEM images showed that ethyl acetate is suitable for the formulation of PLGA nanoparticles with good appearance. Moreover, ethyl acetate showed higher encapsulation efficiency than other solvents. The addition of P188 to formulation did not affect the particle size of PLGA nanoparticles but altered the release patterns of blue dextran from nanoparticles. However, PVA, as a coating material, altered the particle size with increasing the PVA concentration. The nanoparticles were physically stable in the change of particle size during long-term storage. From the results, the PLGA nanoparticles prepared with various contents of poloxamers and PVA, could modulate the particles size of nanoparticles, in vitro release pattern, and encapsulation of water-soluble macromolecules.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.386-395
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• 2013

This study examined social relation of cyber sports supporter's community and social capital as time passes. This study selected spectator sports supporters of cyber sports community based on number of number and history of cyber sports supporter. This community is a representative supporter's club of spectator sports. This study utilized 1,848 members accumulated during three month. To analyze data, Netminer 4.0 and social network analysis were used. The conclusion is following: First, social relation of cyber sports supporter's community showed up dynamic change. Second, social capital of cyber sports supporter's community shows Sports events and training schedules, player transfer, manager, record, game watching and TV watching, cheering, cheering uniform and tools, players, teams and clubs, game photos and video, etc. This is the poor-get-poorer and the rich-get-richer phenomenon.