• Spatial Information Research
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• v.23 no.2
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• pp.31-38
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• 2015

Remote sensing data is used to increasing efficiency on benthic cover type survey. Satellite and aerial imagery has variance of reflectance by water column effect even if bottom is consisted with same cover type and condition. This study tried to analyze advances of surveying extent and accuracy through water column correction of CASI-1500 hyperspectral image. Study area is coast of Gangneung city, South Korea where benthic environment is rapidly changing with bleaching of coral reef. Water column correction coefficient was estimated using regression models between water reflectance ($R_W$) and depth for sand bottom then the coefficients were applied to whole image. The results shows that expanded interpretable depth from 6-7m to 15m and decreased variation of reflectance by depth. Additionally, water column corrected reflectance image shows 13%p increased accuracy on benthic cover type classification.

• Journal of Korean Biological Nursing Science
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• v.17 no.2
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• pp.159-168
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• 2015

Purpose: The purpose of this study was to determine the effects of auricular acupressure on menstrual pain, difficulties in daily life, negative feelings and autonomic nervous responses among college students. Methods: A Randomized Controlled Trial design was used. The treatment group A (n=12) receivedauricular acupressure therapy on the first or second day of their menstrual period. Treatment group B (n=18) regularly received an auricular acupressure therapy once a week for a month. The control group (n=19) received no auricular acupressure therapy. An independent t-test was used to examine pre-post test differences in the group. The ANOVA and Scheffe test were used to examine pre-post test differences among the group. Results: Subjects in treatment group A showed significantly less menstrual pain, difficulties in daily life, and negative feelings than the control group did. The participants in treatment group B also showed significantly less difficulties in daily life and negative feelings than the control group. Conclusion: The findings support that auricular acupressure therapy on menstrual periods is effective in controlling menstrual pain, difficulties in daily life, and negative feelings. As the method is simple, it would be useful for female students to learn to use this method to alleviate the symptoms related to menstruation through self care.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.2
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• pp.187-195
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• 1999

A series feedback DRO operating at 3.2 GHz applicable to the spectrum analyzer as the second local oscillator, is designed and fabricated. We can obtain a low noise by utilizing the small signal S-parameter of the transistor and adjusting the reflection coefficient from the coupling coefficient between dielectric resonator and microstrip line. The results show that output power is 10.50 dBm, a stable low phase noise is -116 dBc/Hz at a 10 kHz offset frequency and a harmonic characteristic is 19.33 dBc.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.4
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• pp.273-278
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• 2016

Responded threshold level in hearing screening depends on the noise level of test surroundings, physiological characteristics of hearing organs, excessive sound source exposures, and so on. The purpose of this study is to obtain the basic information of hearing threshold level at each frequencies in children with passed hearing screening. Subjects were 110 children, aged were from 3.3 to 16.3 ($9.01{\pm}2.52$), who were at private speech language pathological clinics and daycare centers. Methods of Hearing screening were tympanometry, acoustic reflex threshold, automated otoacoustic emission, and pure tone screening. The subjects were in normal criteria of hearing screening. The differences of hearing threshold among ages and frequencies were measured by means of repeated measures ANOVA. The mean of hearing thresholds level was observed $16{\pm}6.49$, $11.5{\pm}4.79$, $6.86{\pm}4.99$, $5.95{\pm}6.65$ dB HL in the right ear and $15.68{\pm}6.01$, $9.95{\pm}5.24$, $5.72{\pm}5.21$, $5.63{\pm}7.04$ dB HL in the left ear, in frequency of 500, 1,000, 2,000, 4,000 Hz respectively. There was a significant difference between 500 and 1,000, 2,000, 4,000 Hz (p=.000), between 1,000 and 2,000, 4,000 Hz (p=.000).

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.699-706
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• 2016

This study aimed to propose the necessity and system establishment of noise reduction facility via evaluating noise level exposed by the radiographer due to MRI scan. Noise measurements were carried out using at S general hospital in Daejeon using 1.5 Tesla MRI (7 exams) and 3.0 Tesla MRI (16 exams), while using SC-804 noise meter. The measurement distance was from the soundproof door of the MRI room to the radiographer which measured 100cm, and the measurement height, the height to the radiographer's ears when working, 100cm. The noise measured for each exam was an average of three measures per exam which observed the noise occurring in each sequence recorded every 20 seconds. As the results, the maximum of noise exposed by the radiographer is 73.3 dB(A), which is MRCP by the 3.0 Tesla device, and also the maximum of average noise is 66.9(3.1) dB(A), which is Myelogram by the 3.0 Tesla device. Average noise by each device is 61.9(4.1) dB(A) by the 3.0 Tesla device and 52.0(3.1) dB(A) by the 1.5 Tesla device, which comes to the result that the 3.0 Tesla MRI device is about 10 dB(A) degree higher(p <0.001). The noise level exposed by the radiographer does not affect auditory acuity, but the level is able to incur a non auditory effect. The reflect sound can be removed by installing curtains in the rear wall of MRI control room in order to reduce the noises, but, first of all, An institutional system is needed in order to prevent noise.

• Journal of the Korean Magnetics Society
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• v.18 no.3
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• pp.120-125
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• 2008

In this study, NiCoZn ferrites with the variation of sintering temperature and chemical composition were prepared by the coprecipitation. Microstructures Crystal structure of NiCoZn ferrites were analyzed by XRD and their electric magnetic characteristics were analyzed by LCR meter and their morphology observed by SEM. We identified that these powders have a typical NiCoZn spinel structure and nanoparticles average size of 40 nm. The impurity, the initial permeability and the Q factor value are the lowest of sintered NiCoZn ferrite at $1250^{\circ}C$. Also, we measured S-parameter for $(Ni_{0.4}Co_{0.1}Zn_{0.5})Fe_2O_4$ which showed a maximum reflection loss of -3.1 dB at 6 GHz for the 2 mm thick sample. From this result, we found that the NiCoZn ferrite can be used in ferrite microwave-absorbing application at a higher frequency region (> 6 GHz).

• Journal of the Korean Magnetics Society
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• v.19 no.2
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• pp.62-66
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• 2009

The soft magnetic FeSiCr were processed the ball-mill for 30 hours and the shape of FeSiCr particles was changed from sphere to flake type, which was observed using scanning electron microscope. The complex permittivity and permeability spectra and reflection loss of FeSiCr-rubber composite was measured using Network Analyzer in order to investigate the relationship between the microwave absorption and the material constants. The matching frequency shifted toward lower frequency range with microwave absorber thickness, and microwave absorber with FeSiCr-rubber composite showed a maxium reflection loss of -8.3 dB at 1.86 GHz for a 1.3 mm thickness.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.89-95
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• 2018

In this paper, we analyze the antenna performance changes caused by the aircraft structure, diffraction and reflection, when the direction finding antenna used in the aircraft is mounted on the aircraft. Direction finding antenna is an antenna that receives radar threat signal in the direction finding device of aircraft electronic warfare system. Recently, because various antenna are mounted on an aircraft, various analyzes such as antenna performance and interference analysis are required. Therefore, the electromagnetic analysis was carried out by installing a broadband direction finding antenna with 50% bandwidth on simulated aircraft, and the direction finding performance was analyzed by comparing the single antenna performance with the performance mounted on the aircraft. The analyzed direction finding accuracy was $6.47^{\circ}$ RMS and predicted to be suitable as an antenna for aircraft direction finding antenna.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.19-22
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• 2007

Recently, the population of people exploring High Mountain trekking or expedition is increasing as an increase in the backpackers. Many accidents occurring at High Mountain above 6,000 m are the results of snow blindness. The damage of cornea and/or retina is direct cause of snow blindness. The UV intensity increases on the hand, along with the altitude caused by decrease in the atmospheric pressure, on the other hand the reflections by bright snow at high mountain area. And it increases approximately 3 times and 4 times higher than the ground level at altitude of 4,000 m and 8,000 m, respectively. The use of sunglasses is more favorable than goggles for the protection of snow blindness at High Mountains. The eye frames that have high mechanical strength and the plastic lenses which can protect UV 100% are recommended. The attachable shielding pads are needed to prevent the incident UV light reflected or scattered from the gap between glasses frame and face. The sunglasses must have flexible and long temples to wind the ears adequately for the prevention of detachment during climbing and it is recommended that the metal frame to be coated with plastics to prevent the eye surroundings from frostbite.

• Korean Journal of Optics and Photonics
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• v.22 no.1
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• pp.46-52
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• 2011

A confocal microscope was developed utilizing a scanning sample stage based on a home-built double-compound flexure guide. A scanning sample stage with nano-scale resolution consisted of a double leaf spring based flexure, a displacement amplifying lever, a Piezo-electric Transducer(PZT) actuator and capacitance sensors. The performance of the two-axis stage was analyzed using a commercial finite element method program prior to the implementation. A single line laser was employed as the light source along with the Photo Multiplier Tube(PMT) that served as the detector. The performance of the developed confocal microscope was evaluated with a mouse ear skin imaging test. The designed scanning stage enabled us to build the confocal microscope without the two optical scanning mirror modules that are essential in the conventional laser scanning confocal microscope. The elimination of the scanning mirror modules makes the optical design of the confocal microscope simpler and more compact than the conventional system.