• Journal of Preventive Medicine and Public Health
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• v.20 no.2 s.22
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• pp.205-214
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• 1987

For the purpose of evaluating the effect of noise induced hearing loss on the blood pressure, a cross-sectional study was conducted in 481 manufacturing industrial workers in Pusan area consisted of 275 workers from noisier plant (over 90 dB(A), high exposed group) and 206 workers from less noisy plant (below 85 dB(A), low exposed group) from April to Decepmber in 1985. The summarized results were as follows; 1) The degree of hearing loss according to the audible frequency was most notable in 4,000 Hz. 2) The prevalence of hypertension was 14.8% in total examined subjects. And also in 40 dB(A) hearing lost workers, there was no significant difference between high exposed group as 15.5% and low exposed group as 15.8%. 3) In 3 models analyzed by multiple regression technique to obtain the complexed extents of risk factors related to the diastolic blood pressure, especially model III which contain age, body mass index, smoking, alcohol and family history of hypertension, duration of work, noise exposure level and degree of hearing loss in high exposed group was most remarkable compared to the others. 4) The most potential predictor related to the diastolic pressure in high exposed group was the degree of hearing loss. And the next were body mass index, familial history of hypertension and age in order. But in the case of low exposed group, the potential predictors were body mass index, age and familial history of hypertension.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.9
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• pp.6-12
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• 2011

In this paper, we propose a design method for a reliable and improved field-installable optical connectors(FIOC) which are needed for long-distance and low loss FTTH configuration. To this end, we optimize the angle of splicing between the inner fiber and the field fiber of the FIOC, so that the low loss connection of optical fibers is possible without using any angle alignment tools as well as angled cleavers. More precisely, we set the cutting angle of the inner filber and the field fiber to be $2^{\circ}$ by using an angled cleaver and $0^{\circ}{\sim}1^{\circ}$ by using a general fiber cutter, respectively. Splicing these two optical fibers without any further adjustment, we can keep the insertion loss within 0.3dB and the reflection loss within -60dB.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.230-243
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• 1996

Root surface exposure due to gingival recession after periodontal surgery, dentin exposure after root planing elicit pain response when exposed to mechanical, heat, chemical or osmotic stimulation. Especially, patients treated with periodontal surgery, show high frequency and there have been reports showing the 1 out of 7 patients have dentin hypersensitivity. There have been many studies on the clinical effects of various materials on the treatment of dentin hypersensitivity. but, none could provide absolute clinical efficacy. In this study, 45 teeth from 30 patients, who had had periodontal surgery and showed dentin hypersensitivity after surgery were chosen for the experimental group and they were illuminated with laser, 15teeth were chosen for the control group and they were not exposed to laser. After this dentin hypersensitivity was elicited by tactile, compressed air, cold water and then, the degree was evaluated using NRS(Numerical Rating Scale). And during LLLT(Low Level Laser Therapy) semiconductor laser using Gallium - Arsenide as a diode was illuminated for 180 seconds at a frequency of 7(500Hz). This therapy was done 10 times, and each time the changes in dentin hypersensitivity was evaluated using NRS. The results were as follows : 1. After treat with LLLT on dentin hypersensitivity due to periodontal surgery, 22.2% showed total loss of dentin hypersensitivity, 60.0% showed loss of tactile dentin hypersensitivity, 48.8% showed loss of compressed air dentin hypersensitivity, 22.2% showed loss of cold water dentin hypersensitivity. 2. As a result of clinical evaluation of dentin hypersensitivity using NRS, there was significant increase in improvement of dentin hypersensitivity in the experimental group compare to the control group(P<0.05). And there was almost no natural loss of dentin hypersensitivity in the control group. 3. In comparison of the stages of evaluation, there was significant difference in between experimental and control group. after the second visit(P<0.05), and the difference increased with each visit.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.69-79
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• 1999

In this paper, we proposed a diffuion model of Ti diffused lithium niobate optical waveguide for fabricating waveguides with high refractive index and compared with conventional one. The achivement of low optical insertion loss between waveguide interface and single mode fibers was discussed as a function of Ti thickness for $\lambda$=1.55$\mu\textrm{m}$ The proposed diffusion method exhibited higher refractive index waveguide than conventional one for $\lambda$=0.6328$\mu\textrm{m}$ We have achieved the total fiber-waveguide-fiber insertion loss as low as 0.5dB/cm in z-cut and 1$\pm$0.5dB/cm in x-cut for both TM and TE mode of Mach-Zehnder interferometric waveguide in the range of Ti thickness 1000-1400$\AA$ for $\lambda$=1.55$\mu\textrm{m}$ From these results, this diffusion model for making a low loss waveguide can be used for low-power-modulators and switches.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1292-1299
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• 2003

In this paper, we fabricated new GaAs-based dielectric-supported air gapped microstriplines(DAMLs) using the surface MEMS and the LPF for Ka-band using the fabricated DAMLs. We elevated the signal lines from the substrate, in order to reduce the substrate dielectric loss and obtain low losses at millimeter-wave frequency band with wide impedance range. We fabricated LPF with DAMLs for Ka-band. Due to reducing the dielectric loss of DAMLs, the insertion loss of LPF can be reduced. Miniature is essential to integrate LPF with active devices, so that we fabricated LPF with the slot on the ground to reduce the size of the LPF. We compared a characteristic to LPF with the slot and LPF without the slot.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.77-82
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• 2001

Error characteristics of a mirror loss measurement system using an exponential decay method were studied, with the two samples having about 200-ppm-loss and 30-ppm-loss, respectively. In order to minimize the decay signal deviation from an exponential curve due to cavity length fluctuation, a data average method was tried. The data average method significantly improved the exponential curve fitting error of the decay signal, so that for a 6 decay signal data average the loss measurement error was reduced by about 2.4 times for the 200-ppm-loss mirror and 1.3 times for the 30-ppm-loss mirror compared with a single shot measurement. Day-to-day mirror loss repeatability error for the two samples was investigated. The repeatability error was measured to be about 5% for the 200-ppm-loss mirror and about 26.4% for the 30-ppm-loss mirror. Low decay signal average effect and high repeatability error in the low loss mirror measurement were explained with non-uniform spatial loss distribution of the sample and contamination from the environment, in addition to the error sources of the mirror loss measurement system itself. The influence of cavity length fluctuation and cavity length measurement error on the mirror loss measurement system performance was theoretically calculated. It confirmed that the requirement for the cavity length parameters was not so strict in the mirror loss measurement system of several ppm resolution. ution.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.5
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• pp.185-189
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• 2005

This paper focuses on the design for Rx/Tx switch module of GSM(global standard mobile) band, characterization of a miniature, low power and dual-band implementation of the front-end switch module with low-pass filer And the effort to make agreement between the simulated design and the measured data for these solutions takes the place through accumulated design and manufacturing data library. We present the design, modeling and measurement of switch module integrating GSM Rx/Tx switching circuit and LPF(low pass filter) on a LTCC(low temperature co-fired ceramic) substrate. For GSM application, insertion and return loss of the low pass filter designed was less than 0.3 dB which was less than 12.7 dB at 900 MHz. The LTCC switch module contained 10 embedded passives and 3 surface mount components integrated on 4.6$\times$4.8$\times$1.2 mm, 6-layer multi-layer integrated circuit. The insertion loss of switch module measured at 900 MHz was 11 dB. In both of the design approach yielded excellent agreement between measured and simulated results.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.607-612
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• 2002

This paper presents the first domestic model product of hybrid Insulation low-loss type pole transformer, with increased overload ability, increased life, reduced loss, focusing improved short-circuit characteristics. The capacity of this transformer is 100 KVZ, rates first voltage 13200 V and secondary voltage 230/115 type. The volume of model transformer that was produced in high temperature using hybrid insulation can be reduced to 10-20% in comparison with that of present transformer with the same capacity. In this paper, we did short-circuit test and tested general characteristics of model transformer. In addition, we suggested design application new concept and methods thorough this experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.158-163
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• 2008

Muffler design in the exhaust system is critical to provide for low noise in shipboard spaces. In an attempt to effectively design the low noise muffler, it is important to evaluate the performance of the muffler considering not only the noise, but also pressure drop as well. For this purpose, a test system of large exhaust muffler for ship propulsion systems was designed based on ISO 7235. The substitution test for determining both the insertion loss and pressure drop of mufflers was carried out. A ship exhaust muffler is considered as a test example and the insertion loss and pressure drop are obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.600-605
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• 2014

Two mufflers for a large-size sedan are suggested aiming (1) sporty-sound and (2) quiet-sound as well as both satisfying low back-pressure and low manufacturing cost. Transmission loss prediction considering heat and flow may increase the accuracy and reduce the development cost in muffler design; thus, GT-power prediction considering heat, flow, and acoustics is utilized. By understanding the fundamentals of flow-acoustic theory in small orifice(hole), an effective muffler design concept is proposed. Vehicle tests show the consistence with predictions for sound; also a back-pressure test bench confirms the advantage in pressure drop for both suggested mufflers. Those suggested mufflers also have advantages in manufacturing cost due to simplicity of the design.