• Journal of Fisheries and Marine Sciences Education
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• v.18 no.3
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• pp.293-301
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• 2006

This study was undertaken to prolonging the freshness in Squid(Todarodes pacificus) on the effects of ice storage methods(tap water ice, electrolytic water ice) using stainless diaphragm electrolytic instrument and also test an efficiency of instrument. Basically, stainless diaphragm electrolytic instrument studied for changes of pH on difference water flow and ampere. The lower water flower and higher ampere made low pH on acid part of electrolytic instrument. Squid samples were stored in tap water ice, acid part of electrolytic water and base part of electrolytic water and used in studying the changes of VBN and skin color through storage. Acid water had strong sterilization effects and VBN was lower levels of acid water than the others. Base water had not sterilization effects. Tap water ice storage was more sterilizing effects than base water ice storage but less effects than acid water ice storage. Lightness of Squid skin showed getting decrease at storage of ice water of all storage methods but acid water ice storage showed more retarding than the other two storage. From these results, it could be suggested that acid electric water ice storage is effective in extendance the shelf-life of squid at chilled storage.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.41-47
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• 2002

La/sub 1-x/Ca/sub x/MnO₃ manganese oxide were grown using the floating zone image furnace with halogen lamps as heat source. The growth condition was 4∼6 mm/hr growth rate in air atmosphere, 45∼50 rpm and 20∼25 rpm of rotation rate of feedrod and growing crystal, respectively. Characterization analyses of the crystal were carried out using XRD, SEM, and EPMA. Orientation of crystal was determined using EBSD. The electromagnetic properties were measured with Quantum Design PPMS by 4 point probe method and resulted MR value of 462% at 215 K.

• Journal of the Korean Magnetics Society
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• v.17 no.4
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• pp.156-161
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• 2007

To develop array magnetic sensors, specular-type giant magnetoresistive- spin valve (GMR-SV) film of Glass/Ta(5)MiFe(7)/IrMn(10)NiFe(5)/$O_2$/CoFe(5)/Cu(2.6)/CoFe(5)/$O_2$/NiFe(7)/Ta(5)(nm) was deposited by using a high-vacuum sputtering system. One of 15 way sensors in the area of $8{\times}8mm^2$ was Patterned a size of $20{\times}80{\mu}m^2$ in multilayer sample by Photo-lithography. All of 15 sensors with Cu electrodes were measured a uniform magnetic properties by 2-probe method. The highest magnetic sensitivity of MR and output voltage measured nearby an external magnetic field of 5 Oe were MS = 0.5%/Oe and ${\triangle}$V= 3.0 mV, respectively. An easy-axis of top-free layers of $CoFe/O_2/NiFe$ with shape anisotropy was perpendicular to one of bottom-pinned layers $IrMn/NiFe/O_2/CoFe$. When the sensing current increased from 1 mA to 10 mA, the output working voltage uniformly increased and the magnetic sensitivity was almost stable to use the nano-magnetic devices with good sensitive properties.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.63-63
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• 2011

비정질 반도체/절연체의 직류와 교류 전도도 스펙트럼은 주파수에 대한 거듭제곱의 법칙 (power-law)을 따르는 보편성이 있음이 확인되었다. 이러한 보편성은 다양한 비정질 반도체/절연체 물질에서 공통적으로 관찰되었으며 현재까지 이 보편성의 물리학적 원인이 정확히 규명되지 않고 있다. 이 보편성을 설명하기 위한 모델로서 비정질 반도체/절연체 내의 전자/정공의 호핑 전도기구 (hopping conduction mechanism)가 제시된 바 있으며 다양한 비정질 시스템의 전도도 스펙트럼 해석에 인용되고 있다. 그러나 직.교류 전도기구 사이의 상이함에 대한 이견이 있으며 현재까지 정확히 규명된 바 없다. 본 연구에서는 비정질 GeSe 반도성 물질의 전도도 스펙트럼을 10 Hz-1 MHz 주파수 대역에서 측정하였으며 이를 위해 백금 상.하부 전극을 갖는 크로스바(crossbar)형의 금속-절연체-금속구조의 2단자 소자를 제작하였다. 측정 스펙트럼으로부터 본 연구의 GeSe 물질이 앞서 언급한 비정질 물질의 보편성에 부합함을 확인하였으며 스펙트럼 내의 직류와 교류 성분을 명확히 분리할 수 있었다. 직.교류 전도도 스펙트럼의 명확한 기구 분리를 위하여 4개의 상이한 면적을 갖는 크로스바에 대한 측정을 실시하였으며 그 결과로 직.교류 전도도의 상이한 면적 의존성을 관찰하였고 이를 근거로 직.교류 전도도가 서로 다른 전도기구에 기인함을 간접적으로 알 수 있었다. GeSe의 전도도 스펙트럼의 온도 의존성 실험을 위해 시편의 온도를 20-300 K 범위에서 변화시키며 전도도 스펙트럼을 측정하였으며 이를 통해 교류 전도도 스펙트럼 내에 상이한 두 개의 전도 기구가 혼재해있음을 규명하였다.

• Journal of the Korea Convergence Society
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• v.6 no.1
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• pp.109-114
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• 2015

A circularly polarized small UHF RFID reader antenna is presented. The antenna is composed of four elements and printed on the plastic substrate(${\varepsilon}_r=2.2$, t=5mm). Each element is fed by a probe which is sequentially connected to the feed line. The feed line is manufactured on the FR-4 substrate(t=1.0mm, ${\varepsilon}_r=4.7$). The simulation results shows that the antenna can be achieved a return loss of 12dB, gain of 3.46dBic over the UHF band of 902-928MHz. According to our simulation results, two prototype antennas are manufactured and measured. The obtained antennas operate in UHF RFID bands and can be adapted for various portable applications. In addition, a parametric study is conducted to facilitate the design and optimization processes.

• Polymer(Korea)
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• v.36 no.4
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• pp.494-499
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• 2012

In this work, the effect of multi-walled carbon nanotube (MWCNT) on electromagnetic interference shielding effectiveness (EMI SE) and mechanical properties of MWCNT-reinforced polypropylene (PP) nanocomposites were investigated with varying MWCNT content from 1 to 10 wt%. Electric resistance was tested using a 4-point-probe electric resistivity tester. The EMI SE of the nanocomposites was evaluated by means of the reflection and adsorption methods. The mechanical properties of the nanocomposites were studied through the critical stress intensity factor ($K_{IC}$) measurement. The morphologies were observed by scanning electron microscopy (SEM). From the results, it was found that the EMI SE was enhanced with increasing MWCNT content, which played a key factor to determine the EMI SE. The $K_{IC}$ value was increased with increasing MWCNT content, whereas the value decreased above 5 wt% MWCNT content. This was probably considered that the MWCNT entangled with each other in PP due to an excess of MWCNT.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.865-872
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• 2002

The conventional Rotman lens antenna using a waveguide lens has the bended waveguide from the inner lens contour to the antenna element. However in this paper the improved Rotman lens antenna having a straight waveguide is proposed. By applying this technique, the beam steering antenna for BMWS application which has 3 input ports and 6 antenna elements consisted of open-ended waveguide has been designed and fabricated. From the measurement, the gain of the beam steering antenna is 15.4 ~ 17.2 dB. The direction angle is 0$^{\circ}$, +14$^{\circ}$~ +16$^{\circ}$, -15$^{\circ}$~ -16$^{\circ}$ and the side lobe level is -l0 ~ 20 dB.

• Progress in Superconductivity
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• v.4 no.1
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• pp.74-79
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• 2002

High-speed probe made to test single flux quantum(SFQ) circuits was comprised of semi-rigid coaxial cables and microstrip lines. The impedance was set at 50 $\Omega$to carry high-speed signals without much loss. To do performance test of high-speed probe, we have attempted to fabricate a test chip which has a coplanar waveguide(CPW) structure. Electromagnetic simulation was done to optimize the dimension of CPW so that the CPW structure has an impedance of 50$\Omega$, matching in impedance with the probe. We also used the simulation to investigate the effect of the width of signal line and the gap between signal line and ground plane to the characteristics of CPW structure. We fabricated the CPW structure with a gold film deposited on Si wafer whose resistivity was above $1.5\times$10$_4$$\Omega$.cm. The magnitudes of S／sub 21／ of CPW at 6 ㎓ in simulations and in the actual measurements done with a network analyzer were: -0.1 ㏈ and -0.33 ㏈ (type A),-0.2 ㏈ and -0.48 ㏈ (type B), respectively. Using the test chip, we have successfully tested the performance of high-speed probe made for SFQ circuits. The probe showed the good performance overthe bandwidth of 10 ㎓.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.25-28
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• 2002

Contact type Ic measurement system is needed to measure Ic continuously for long Bi-2223 tapes. Voltage and current terminals were designed several shapes for 4-probe method Ic measurement. Voltage terminals were made with brass and current terminals were made with Cu. We used 2 kinds of Bi-2223 tapes with different strength. When we measured Ic of Bi-2223 tape with Ag-Mg sheath, The proper weight was 0.3 kg and sharp pin type was better. according to voltage terminal shape and load. In case of Bi-2223 tape with Ag-Mn sheath, the proper terminal weight was 4 kg and sharp pin type was bad. It was possible to make continuous contact type Ic measurement system because We could get proper data - terminal shapes and loads - through these experiments.

• Journal of Applied Reliability
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• v.8 no.4
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• pp.155-166
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• 2008

PTH cracks are caused by the mismatch of coefficient of thermal expansion(CTE) between polymer and laminated materials, and are one of the main failure mechanisms of multi layer boards. In spite of its importance, it is usually hard to measure or detect them because of its small size and invisibility. To detect PTH cracks more effectively, this paper proposes a theoretical model that can estimate the resistance value from crack size of PTHs. Using four-point probe resistance measurement method, the resistance value of test coupons is measured. Through measured data, we verify the validity of the proposed theoretical model and set up criteria of failure.