• Fire Science and Engineering
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• v.26 no.1
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• pp.96-101
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• 2012

The buildings of domestic wear the upper floors and an underground in-depth reconciliation tendency to do and the possibility of fire occurrence at the time of formation accident is coming to be high. Therefore will be scattered to various place and is established and prevention of disaster information of the receiver which will integrate there is a necessity which will manage. In this paper away where each receiver is installed in the fire for the remote monitoring and controld able to connect to the Internet and fiber optic cable that can be networked fire receiver and control desk was constructed. Between each device can be used by the fire, and more depending on the status of monitoring and alarm, control and maintenance can be performed to develop an integrated management system. The system is evaluated by the criteria of the KFI, and for each segment of the signal propagation time to perform experiments confirmed the reliability of the performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.677-682
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• 2015

In this paper, we investigated the effect of light on the performance of the receiver system noise and external noise added from the ever-present influence in general optical system. And calculated the reception sensitivity of the receiver at the time of off-keying transmission - from the optical transmission system in consideration of the case that the photo detector has a quantum yield of less than one-one. Not less than 50 it was confirmed that it is possible to configure the low power system is calculated and compared with the case where less than 300 the receiver sensitivity of the optical system to maintain the standard error probability. However, even if these values were considered, and the preamplifier in the receiver, considering a case of using a low-output light source, so that a heavy burden in the value less than the actual system installation, using the light source having less than the output, as shown in Figure 3, the results that were obtained also may be used.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.853-858
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• 2022

In this paper, we show a simultaneous transmission of underwater optical wireless power transfer and underwater optical wireless communication. A laser diode is used for electric-to-optic conversion at the transmitter and a solar cell is used for optic-to-electric conversion at the receiver. We optimized the transmitter and receiver for the best performance. The laser diode is a 100-mW laser diode and showed a conversion efficiency of 18.5%. The experimental results showed a 0.33-% DC-to-DC underwater power transfer efficiency at 5 m and a data rate of 100 kbps at 1 m.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.9
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• pp.721-728
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• 1991

In this paper, a magneto-optic modulator has been designed by using single crystal BSO and polycrystal ZnSe as Faraday cells. And practical core-type optical current sensors using pure iron and permalloy have been prepared and experimented. In order to obtain efficient magnetic field detection, LED(NEC OD08358, 0.87 $\mu$m) was used as optical source, PIN-PD(OD-8454)as optical receiver and multi-mode optical fiber (100/140$\mu$m) as transmission line. The characteristics matrix of the optical element was calculated by Stokes parameter, and optic modulation characteristics equations were derived by Muller matrix. Electromagnetic analysis program (FLUX 2D, micro VAX 3600) by finite element method was used to find the magnetic flux density around the core. The measuring error of the output voltage to input current has been masured below 5% in the range of 50A to 1000A. As the temperature was changed from -20$^{\circ}C$ to 60$^{\circ}C$, the maximum measurement error of the optical output has been found to be 0.5% at 60$^{\circ}C$. These experimental results show good temperature and linearity characteristics. The SNR of the overall system was 47dB in case of 600A (250.2 Oe) conductor current and the system has good noise immunity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.1
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• pp.16-24
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• 1998

In a high speed long haul fiber optic communication system using modulation, fiber chromatic dispersion and laser chirping can cause serious performance degradations. In this paper, the combined effect of laser chirping and chromatic dispersion on the per- formance of 2.5[Gbps] rate lightwave systems operating at a wavelength of 1550[nm] was investigated. Also we used an optical equalizer to compensate the laser chirping and fiber dispersion, and knew that the receiver sensitivity was improved by about 2 ~ 4[dB].

• Journal of Korean Neurosurgical Society
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• v.57 no.1
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• pp.23-31
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• 2015

Objective : The aims of this study were to investigate the quantitative relationship between pituitary macroadenoma size and degree of visual impairment, and assess visual improvement after surgical resection of the tumor. Methods : The medical records of patients with pituitary adenoma, who had undergone trans-sphenoidal adenectomy between January 2009 and January 2011, were reviewed. Patients underwent an ocular examination and brain MRI before and after surgery. The visual impairment score (VIS) was derived by combining the scores of best-corrected visual acuity and visual field. The relationship between VIS and tumor size/tumor type/position of the optic chiasm was assessed. Results : Seventy-eight patients were included (41 male, 37 female). Thirty-two (41%) patients experienced blurred vision or visual field defect as an initial symptom. Receiver operating characteristic curve analysis showed that tumors <2.2 cm tended to cause minimal or no visual impairment. Statistical analysis showed that 1) poor preoperative vision is related to tumor size, displacement of the optic chiasm in the sagittal view on MRI and optic atrophy, and 2) poorer visual prognosis is associated with greater preoperative VIS. In multivariate analysis the only factor significantly related to VIS improvement was increasing pituitary adenoma size, which predicted decreased improvement. Conclusion : Results from this study show that pituitary adenomas larger than 2 cm cause defects in vision while adenomas 2 cm or smaller do not cause significant visual impairment. Patients with a large macroadenoma or giant adenoma should undergo surgical resection as soon as possible to prevent permanent visual loss.

• Journal of Korean Neurosurgical Society
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• v.66 no.6
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• pp.664-671
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• 2023

Objective : The optic nerve sheath diameter (ONSD)/eyeball transverse diameter (ETD) ratio is a more reliable marker of intracranial pressure than the ONSD alone. We aimed to investigate the predictive value of the ONSD/ETD ratio (OER) for neurological outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods : Adult patients with aSAH who visited the emergency department of a tertiary hospital connected to a South Korean university between January 2015 and December 2021 were included. Data on patient characteristics and brain computed tomography scan findings, including the ONSD and ETD, were collected using a predefined protocol. According to the neurological outcome at hospital discharge, the patients were divided into the unfavorable neurological outcome (UNO; cerebral performance category [CPC] score 3-5) and the favorable neurological outcome (FNO; CPC score 1-2) groups. The primary outcome was the association between the OER and neurological outcomes in patients with aSAH. Results : A total of 171 patients were included in the study, of whom 118 patients (69%) had UNO. Neither the ONSD (p=0.075) nor ETD (p=0.403) showed significant differences between the two groups. However, the OER was significantly higher in the UNO group in the univariate analysis (p=0.045). The area under the receiver operating characteristic curve of the OER for predicting UNO was 0.603 (p=0.031). There was no independent relationship between the OER and UNO in the multivariate logistic regression analysis (adjusted odds ratio, 0.010; p=0.576). Conclusion : The OER was significantly higher in patients with UNO than in those with FNO, and the OER was more reliable than the ONSD alone. However, the OER had limited utility in predicting UNO in patients with aSAH.

• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.81-90
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• 2019

The data rate for transmission through fiber-optic cables has increased to 400 Gbps in single-wavelength channels. However, speeds up to 1 Tbps are required now to meet the ever-increasing bandwidth demand driven by the diverse requirements of contemporary applications for high-quality on-demand video streaming, cloud services, various social media, and emerging 5G-enabled applications. Because the data rates of the per-channel optical interfaces depend strongly on the operational speed of the optoelectronic devices used in optical transceivers, ultrahigh-speed photonic devices and components, and eventually, chip-level transmitter and receiver technologies, are essentially required to realize futuristic optical transceivers with data rates of 1 Tbps and beyond. In this paper, we review the recent progress achieved in high-speed optoelectronic devices, such as laser diodes, optical modulators, photodiodes, and the transmitter-receiver optical subassembly for optical transceivers in data centers and in metro/long-haul transmission.

• Journal of Trauma and Injury
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• v.26 no.3
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• pp.104-110
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• 2013

Purpose: Bedside ultrasonography is available in most emergency departments, and detecting the intracranial pressure is elevated is critical. Our objective is to evaluate the availability of bedside optic nerve ultrasound (ONUS) as a secondary survey for patients with head injuries in the emergency department (ED). Methods: From September, 2012, to March, 2013, we performed a prospective study of patients presenting to the ED after an accident. Patients with head injuries but without obvious ocular trauma or ocular disease were included. The ONUS was performed using a 3 to 12 MHz linear probe on closed eyelids after a primary survey. We analyzed the correlation between the brain computed tomography (CT) findings that suggested elevated intracranial pressure (ICP) and the Optic nerve sheath diameter (ONSD) measured by using ONUS. Results: A total of 81 patients were enrolled. Forty-seven had CT results consistent with elevated ICP, and their mean ONSD was $5.98{\pm}0.59$ mm; the mean ONSD of patients who showed no signs of elevated ICP on CT was $4.63{\pm}0.21$ mm. The sensitivity and the specificity for the ONSD, compared with elevated ICP, were 98.87% and 100%, respectively, when the cut-off value was set to 4.96 mm. The area under curve (AUC) was 0.997 in the receiver operating characteristic curve (ROC curve). Conclusion: An evaluation using ONUS is a simple noninvasive procedure and is a potentially useful tool as a secondary survey to identify an elevated ICP.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.9
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• pp.1198-1206
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• 1997

The flow characteristics of an intermittent fuel injection into a stationary ambient air were investigated using gasoline. The measurements were made by two-channel, air cooling type Phase Doppler Anemometer(PDA) system (DANTEC, 750 MW). And a pintle type injector of MPI (Multi-point Port Injection) system was utilized as a fuel injector. The PDA receiver optic was set up in a 60.deg. C forward scatter arrangement to obtain the optimum scattering signal of fuel droplets. The data were obtained by synchronizing PDA system with the fuel injection period, and the axial and radial velocity and turbulent components of fuel droplets were mainly measured for the analysis of temporal and spatial distribution depending upon the fuel injection pressures.