• Journal of Trauma and Injury
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• v.30 no.2
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• pp.41-46
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• 2017

Purpose: To determine the incidence of post-concussion syndrome (PCS) in Korean patients after minor traumatic brain injury. Methods: We conducted an observational cohort study of a convenience sample of patients presenting to the emergency department of a major academic Korean hospital. Patients who visited the Emergency Department for head trauma were screened. A researcher questioned the subject regarding his or her symptoms. Subjects were contacted by phone approximately 2 weeks after their Emergency Department visit and questioned about subsequent symptoms and subsequent visits for medical care. Results: Only 8% of subjects reported any post-concussion symptoms. Only 0.4% had three or more symptoms which might have met criteria for PCS. The median peak onset of symptoms was 3 days after injury. Conclusion: The incidence of PCS is Korean patients is much lower than that documented for patients in the United States or other western countries. On the other hand, this study results could give an idea that mild trauma could also cause the PCS. Further study is needed to replicate this finding and investigate possible explanations for this difference.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.935-942
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• 2000

In this paper, miniature voltage-controlled oscillator(VCO) for 1.6GHz PCS band is designed and implemented. Colpitts type LC resonating oscillator is designed with multilayer PCB and circuit parameters are optimized using the circuit simulator. Using the optimized design parameters, miniature VCO with 6X6X1.8mm3 (0.065cc)dimensions is fabricated and experimented. Developed VCO has -1.67dBm $\pm$0.5dBm output power level in52.5MHz tunung range, and has -99.33dBc/Hz phase noise performance at 10 KHz frequency offset.

• Journal of the Korean Society for information Management
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• v.34 no.3
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• pp.89-107
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• 2017

This study aims to compare information seeking behavior of 1300K users on PC and mobile phone. Transaction logs of 1300K, a major Korean shopping search engine, were analyzed. These transaction logs were collected over 1 month period, from April 1 to April 31, 2016. The results of this study show that there are a little more mobile sessions than PC sessions. Users conducted slightly more browsing on PCs than mobile phones, whereas users submitted queries more than two times on mobile phones than on PCs. Users clicked more search results on PCs than mobile phones, whereas users made important decision makings such as product purchases more on mobile phones than PCs. Top queries and categories were similar between PCs and mobile phones. Queries and categories on mobile phones were more focused than queries on PCs. Overall, mobile search behavior is more simple, passive, and focused than PC search behavior. The results of this study can be implemented to the effective improvement and development of search services for different devices.

• Resources Recycling
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• v.12 no.6
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• pp.32-37
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• 2003

For the reduction of electromagnetic biological effects from cellular phones, the electrical field radiation from cellular phone antenna is reduced by using partial ferrite material added on the phone case as ground plane. On the given properties (permittivity, permeability and conductivity) of ferrite material, the characteristics of monopole antenna is analysed depending on the variation of ferrite added configuration(thickness and shape). According to this analysis, the design method and direction to minimize the biological effects to human head is proposed in 1.7 GHz band PCS phones. For the exact analysis involving the permittivity, per-meability and conductivity of ferrite material, FDTD numerical method is used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2171-2176
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• 2012

PCs and its peripherals uses more power in standby mode even if they are not actually being used. In particular, PCs and its peripherals used in school and office, plugged in at all times during working hours, but not used much time, even if turned off consume a portion of the power. In this paper, we developed Networked Smart Plug for Power Management of PC & Peripherals which is consist of EMS, Smart Plug, PC Agent and Smart Phone App. for power saving of PC and a variety of peripheral devices in office or home, and evaluated the performance of the system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.881-887
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• 2011

In this paper, we proposed vertically structured radiator for increasing bandwidth and gain of mobile phone internal antenna. The proposed antenna has vertically structured radiator instead of planar structured radiator to improve the antenna characteristics for GSM850/900 and DCS1800/PCS1900 bands. The antenna improve bandwidth of low band with 28 % than planar structured radiator. and also, improve bandwidth of high band with 14 %, efficiency 31.80~86.36 %, average gain -4.956~-0.617 dBi on the GSM850/900 and DCS1800/PCS1900 bands. These results are good performance among the small antenna with vertically structured radiator for increasing bandwidth and gain.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.111-117
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• 2012

With the rapid growth of smart phone technologies, mobile user's demands for using services provided by existing web or portal cites are highly increased. These services, however, are designed for the environment of desktop PCs or laptops in general, so it requires lots of costs for corrections and has difficulties for system protection to use in current mobile devices. In this paper, we design and implement a middleware for android-based smart phone apps to cooperate with a portal system with minimum corrections and function configuration. Our middleware system is working as an interface between an existing portal system and mobile devices to provide harmonious usage and safe system protection.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.84-91
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• 2005

In this papers, we study the characteristics of dual band PIFA(Planar Inverted F antenna) for handy phones using H-type silt in the antenna radiators. Slit types on the antenna radiator vary resonance mechanism of the antenna and affect reactance component of impedance for the antenna. Therefore the antennas resonate at the dual band(cellular -band, Korea-PCS band), the bandwidth, input impedance and radiation patterns of the proposed antenna is affected by the silt length on the radiators. In order to demonstrate the validity of the proposed theory, it is implementation the antenna of the 4 types. From results for the experiment of the implementation antenna, -5 dB bandwidth of return loss is content with the allocated bandwidth of Cellular and Korea-PCS system the gains of the antenna is about -8$\~$ - 1 dB, the radiation patterns for x-polarized or y-polarized are omnidirectional pattern. From above the results of this papers, it is conclude mobile phones antenna for handy phones using this papers results.

• Ocean and Polar Research
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• v.21 no.2
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• pp.117-126
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• 1999

To meet increasing needs for environmentally sustainable management of coastal area, there has been compelling pressure to establish a cost-effective and long-term coastal water quality (CWQ) monitoring system. A remote CWQ monitoring system, STAMP, has been developed and is in operation along the route between Kyema harbor and Anma Island in the southwestern coastal area of Korea. STAMP uses a PCS phone as a telemetry unit to transmit acquired data for monitoring general water quality parameters, and a routinely operating coastal passenger ship or car ferry. STAMP has various merits of low-cost operations; long-term monitoring with secure instrumentation; and stable real-time telemetry of acquired data with-out the loss and noise. It is expected that the system will serve as a very useful tool in the CWQ managing programs of Korea taking the advantage of many coastal passenger ships in various routes including the ships departing from the coastal industrial cities. The acquired data compiled on suspended surface sediment concentrations (SSSC) will be also valuably helpful in understanding the sediment budget across the routes of the vessel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.702-708
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• 2002

In this paper, we design the dual frequency antenna that could easily determine two operation frequencies by its inverted-F antenna structure and spur line length. The spur line is applied to the inverted-F antenna, in order to dual operation characteristics in PCS and cellular frequencies. It has designed by using the IE3D commercial software based on the moment method. As the designed antenna is fabricated and measured, you can see the results such as the return loss, the input impedance, the radiation patterns, and the gain. The size of this antenna is 40 mm$\times$14 mm$\times$9.4 mm, it is compact enough to use as an intenna. Also, This antenna can be used with cellular and PCS phone of domestic market.