• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.73-77
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• 2012

Recently, Interest to the photoconductor, which is used to flat form X-ray detector such as a-Se, $HgI_2$, PbO, CdTe, $PbI_2$ etc. is increasing. In this study, the film layer by using the photoconductive material with particle sedimentation was fabricated and evaluated. The quantization efficiency of the continuous X-ray with the 70 kVp energy bandwidth was analyzed by using the Monte Carlo simulation. With the results, the thickness of film with 64 % quantization efficiency was 180 ${\mu}m$ which is similar to the efficiency of 500 ${\mu}m$ a-Se film. And $HIg_2$ film has the high quantization efficiency of 74 % on 240 ${\mu}m$ thickness. The electrical characteristics of the 239 ${\mu}m$ $Hgl_2$ films produced by particle sedimentation were shown as very low dark current(under 10 $pA/mm^2$), and high sensitivity(19.8 mC/mR-sec) with 1 $V/{\mu}m$ input voltage. The SNR, which is influence to the contrast of X-ray image, was shown highly as 3,125 in low driving voltage on 0.8 $V/{\mu}m$. With the results of this study, the development of the low-cost, high-performance image detector with film could be possible by replacing the film produced by particle sedimentation instead to a-Se detector.

• Science of Emotion and Sensibility
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• v.18 no.4
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• pp.25-34
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• 2015

TThis study explored the requirement of fabric sensor that can measure the motion of the joint effectively by measuring and analyzing the variation in electric resistance of a sensor in accordance with bending and stretching motion of the arm by the implementation of a motion sensor utilizing conductive fabric. For this purpose, on both sides of two kinds of knitted fabric, namely 'L' fabric and 'W' fabric Single Wall Carbon Nano-Tube(SWCNT) was coated, fabric sensor was developed by finishing them in a variety of ways, and the sensor was attached to the arm band. The fabric sensor consisted of total 48 cases, namely background fabric for coating, the method of sensor attachment, the number of layer of sensors, the length of sensor, and the width of sensor. The performance of fabric motion sensors in terms of a dummy arm, that is, a Con-Trex MJ with 48 arm bands around it was evaluated. For each arm band, a total of 48, fastened around the dummy arm, it was adjusted to repeat the bending and stretching at the frequency : 0.5Hz, ROM : $20^{\circ}{\sim}120^{\circ}$, the voltage was recorded for each case after conducting three sets of repeat measurement for a total of 48 cases. As a result of the experiment, and as a consequences of the evaluation and analysis of the voltage based on the uniformity of the base line of the peak-to-peak voltage(Vp-p), the uniformity of Vp-p within the same set, and the uniformity of the Vp-p among three sets, the fabric sensors that have been configured in SWCNT coated 'L' fabric / welding / two layers / $50{\times}5mm$, $50{\times}10mm$, $100{\times}10mm$, and SWCNT coated 'W' fabric / welding / two layers / $50{\times}10mm$ exhibited the most uniform and stable signal value within 5% of the total variation rate. Through all these results of the experiment, it was confirmed that SWCNT coated fabric was suitable for a sensor that can measure the human limb operation when it was implemented as a fabric sensor in a variety of forms, and the optimal sensor types were identified.

• Journal of Korea Technology Innovation Society
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• v.12 no.4
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• pp.687-714
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• 2009

In this paper, we study empirically the relations between financial constraints and dividend adjustment speed of innovative small and medium sized enterprises (SMEs) listed on Kosdaq Market of Korea Exchange. The main results of this study can be summarized as follows. Determinants suggested by the major theories of dividends, namely, residual dividend theory, dividend signaling theory, agency theory, catering theory, and transactions cost theory explain significantly the dividend payout policy of Kosdaq SMEs. Lintner's dividend adjustment model indicates that Kosdaq SMEs have long run target payout ratio, and that Kosdaq SMEs adjust partially the gap between actual and target payout ratio each year. In the core variables of Lintner (1956) dividend adjustment model, past DPS has more effect than current EPS. These results suggest that Kosdaq SMEs maintain stable dividend policy which maintain past DPS level without corporate special reasons. Dividend adjustment speed of innovative Kosdaq SMEs is more fast than that of uninnovative Kosdaq SMEs, and dividend adjustment speed of financial unconstrained innovative Kosdaq SMEs is faster than that of financial constrained innovative Kosdaq SMEs. Futhermore, dividend adjustment speed of innovative Kosdaq SMEs classified by Small and Medium Business Administration is faster than that of unclassified innovative Kosdaq SMEs. The former is linked with financial policies and services like credit guaranteed service, venture investment fund, insurance program, and so on. In conclusion, past DPS and current EPS suggested by the Lintner's dividend adjustment model explain mainly dividend adjustment speed, and financial constraints explain also partially. Therefore, if managers of innovative Kosdaq SMEs can properly understand of the effects of financial constraints on dividend smoothing, they can maintain constantly dividend policy. This is encouraging result for Korea government as it has implemented many policies to commit to innovative Kosdaq SMEs.

• Journal of the Korean Society of Radiology
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• v.3 no.3
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• pp.27-35
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• 2009

In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using double layer technique tio decrease dark current. High efficiency material in substitution for a-Se have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using Hetero junction already used as solar cell, semiconductor. Particle-In-Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in PIB method. To make up for the weak points, double layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity is measured to evaluate double layer radiation sensor material.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.331-337
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• 2006

Cavity-type beam position monitors were developed in collaboration with KEK to use for the future accelerators such as international linear collider (ILC) or x-ray free electron laser (XFEL) in PAL. BPM components such as BPM cavity, beam tubes, waveguides and feedthroughs were assembled by brazing at the same time to reduce mechanical errors during the fabrication. There are four screwed pins around outer rim of the cavity for the tuning of cavity frequency and x-y isolation. The resonance frequency of BPM is 6.422 GHz, the inner diameter of cavity is 53.822 mm, and the range of mechanical adjusting is $+ / - 250{\mu}m$. The x-y isolation was measured better than -40 dB after tuned. Test results of signal forms, x-y isolations, sensitivities are satisfied within requirements for the KEK ATF2 beam line.

• Journal of the Korean Society of Radiology
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• v.8 no.7
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• pp.371-376
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• 2014

The process of flip-chip bump bonding, Au wire bonding and encapsulation were sucessfully developed and modularized. The CdTe sensor and ROIC were optimally jointed together at $150^{\circ}C$ and $270^{\circ}C$ respectively under24.5 N for 30s. To make SnAg bump on ROIC easy to be bonded, the higher bonding temperature was established than CdTe sensor's. In addition, the bonding pressure was lowered minimally because CdTe Sensor is easier to break than Si Sensor. CdTe multi-energy sensor module observed were no electrical failures in the joints using developed flip chip bump bonding and Au wire bonding process. As a result of measurement, shearing force was $2.45kgf/mm^2$ and, it is enough bonding force against threshold force, $2kgf/mm^2s$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1045-1051
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• 2005

We developed an orofacial pains diagnosis/therapy system which can enlarge a therapy effect through a new stimulation. Contrary to its established method, this therapy system(DDTS-1) is a treating method which absorbs a surplus ion charge- the cause of an outbreak of a pain-of the human body using a capacitor. Absorbing a surplus ion charge of the human body with effect, it obtained optimal parameters which is control signal to control charging/discharging a capacitor to be 6Hz, and capacitance to be $0.1\~0.33{\mu}F.$ Through clinical demonstration, experimented on among patients-namely dental pain patients, joint disorders patients, and trigeminal neuralgia patients to verification of system. In result, an EAST stimulater had a very low change of abnormal potential against normal potential before/after being placed under medical care. DDTS-1 showed obvious differences that two potentials are one and the same potential or one potential is similar to the other one. DDTS-1 comparing with EAST showed the remedial value of the comparative advantage in all the medical treatment of pains. Therefore, stimulation of DDTS-1 is more effective than the existing electric stimulation. We verified its validity of ion charge absorption in the human body using capacitor which presented the present thesis. That is, we verified theoretical adequacy of control action in a pain, and its efficiency as well as confidence.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1223-1231
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• 2010

The design is presented for a SATCOM antenna capable of simultaneous multi-band (X/Ku/Ka-Band) communications without replacement of feed horns or change of other parts in the application as a ground satellite terminal for large data transfer. The antenna is the offset configuration and consists of a dual-band(X/Ka-band) feed horn, a single-band(Ku-band) feed horn, a frequency selective surface(FSS) sub-reflector and a parabolic main-reflector. The antenna has a main reflector defining a prime focus and a frequency selective surface sub-reflector defining an image focus. A dual-band feed and a single-band feed are provided at each of the prime focus and image focus. The antenna is designed using 3D EM simulator and the gains measured in X/Ku/Ka-band of the complete antenna assembly is more than 31.6dBi, 36.8dBi, 40.8dBi, and the cross polarization is 21.7dB, 26.6dB, 25.2dB, respectively.

• Journal of the Korean Society of Radiology
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• v.3 no.1
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• pp.11-15
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• 2009

In this study, the basic research verifying possibility of applications as radiology image sensor in Digital Radiography was performed, the radiology image sensor was fabricated using a multi-layer technique to decrease dark current. High efficiency materials in substitution for Amorphous Selenium(a-Se) have been studied as a direct method of imaging detector in Digital Radiography to decrease dark current by using PN junction or Hetero junction already used as solar cell, semiconductor. Particle-In -Binder method is used to fabricate radiology image sensor because it has a lot of advantages such as fabrication convenient, high yield, suitability for large area sensor. But high leakage current is one of main problem in Particle-In -Binder method. To make up for the weak points, multi-layer technique is used, and it is considered that high efficient digital radiation sensor can be fabricated with easy and convenient process. In this study, electrical properties such as leakage current, sensitivity, signal linearity is measured to evaluate multi-layer radiation sensor material.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.300-306
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• 2004

Eight cation or anion-responsive polymer membranes were prepared by a casting procedure employing polyvinyl chloride, Bis (2-ethylhexyl)sebacate and each electroactive material in the ratio of 66 : 33 : 1. The resulting membranes were separately installed onto the sensitive area of the ionic electrodes to produce an 8-channel taste sensor array. The taste sensors of the array were connected to a high-input impedance amplifier and the amplified sensor signals were interfaced to a PC via an A/D converter. The taste evaluation system was applied to a discriminant analysis on six groups of marketed beverages like sikhye, sujunggwa, tangerine juice, ume juice, ionic drink and green tea. When the signal data from the sensor array were analyzed by principal component analysis after normalization, the 1st, 2nd and 3rd principal component explained most of the total data variance. The six groups of the analyzed beverages were discriminated well in the three dimensional principal component space. The half of the five groups of the analyzed beverages was also discriminated in the two dimensional principal component plane.