• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.43-52
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• 1999

We propose a new method for tuning of center wavelength in photorefractive filter using $LiNbO_3$ crystal doped with 0.015Wt.% Fe. through the filter bandwidth property analysis using the geometrical method, a new wavelength selectivity theory was presented. In this scheme, the tuning of the center wavelength can be achieved by the real time incident angle control of the received heam, which was gotten by the spatial light modulator. So, tuning time depend on the response time of the SLM and results in the high speed turing. Because the use of thermally fixed grating in our filter, it has uniform diffraction property to the all filtering wavelength. Designed tunable filter has 4nm bandwidth and composed of the three channel with 10nm space. From the optical experiment, we get the 4.5nm, 4.25nm, 4nm bandwidth and 1530.5nm, 1540.5nm, 1549.5nm center wavelength respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.454-459
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• 2013

For the purpose of rapid development and superior design quality assurance, sophisticated finite element model for SOM(Spatial Optical Modulator) piezo actuator of MOEMS device has been developed and evaluated for the accuracy of dynamics and residual stress analysis. Parametric finite element model is constructed using ANSYS APDL language to increase the design and analysis performance. Geometric dimensions, mechanical material properties for each thin film layer are input parameters of FE model and residual stresses in all thin film layers are simulated by thermal expansion method with psedu process temperature. $6^{th}$ mask design samples are manufactured and $1^{st}$ natural frequency and 10V PZT driving displacement are measured with LDV. The results of experiment are compared with those of the simulation and validate the good agreement in $1^{st}$ natural frequency within 5% error. But large error over 30% occurred in 10V PZT driving displacement because of insufficient PZT constant $d_{31}$ measurement technology.

• ETRI Journal
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• v.30 no.6
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• pp.826-832
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• 2008

The metal-ferroelectric-metal (MFM) capacitor in the ferroelectric random access memory (FeRAM) embedded RFID chip is used in both the memory cell region and the peripheral analog and digital circuit area for capacitance parameter control. The capacitance value of the MFM capacitor is about 30 times larger than that of conventional capacitors, such as the poly-insulator-poly (PIP) capacitor and the metal-insulator-metal (MIM) capacitor. An MFM capacitor directly stacked over the analog and memory circuit region can share the layout area with the circuit region; thus, the chip size can be reduced by about 60%. The energy transformation efficiency using the MFM scheme is higher than that of the PIP scheme in RFID chips. The radio frequency operational signal properties using circuits with MFM capacitors are almost the same as or better than with PIP, MIM, and MOS capacitors. For the default value specification requirement, the default set cell is designed with an additional dummy cell.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.400-400
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• 2010

우리는 기본 진공 $10^{-11}\;Torr$의 UHV surface magneto-optical Kerr effect (SMOKE) 시스템을 quarter-wave plate를 사용하였던 기존의 방식에서 PEM (photo elastic modulator)를 사용하는 방식으로 장비의 기능을 향상시켰다. 기존 quarter-wave plate를 사용하는 방식의 경우 Kerr signal을 구하기 위해 편광자와 검광자를 수직으로 두어 광량을 0으로 만들어야 한다. 그러나 금속의 경우 대부분 가시광선 영역에서 큰 반사율 때문에 측정되는 광량이 편광자와 검광자를 거치면서 넓은 각도 범위에서 최소값을 갖기 때문에 정확한 영점을 잡는 데 한계가 있다. 이러한 단점을 해결하기 위하여 우리는 PEM을 이용한 위상변조방식을 사용하였다. 위상변조 방식은 Kerr signal과 관계된 양을 PEM을 이용하여 50 kH ($1{\omega}$)와 100 kH ($2{\omega}$)의 진동 주파수에 공조시키고 이를 Lock-in-amplifier를 사용하여 탐지하기 때문에 좋은 sensitivity를 얻을 수 있을 뿐 아니라 Kerr ellipticity와 Kerr rotation을 동시에 측정할 수 있다. 자화에 필요한 전자석은 순철로 된 코어를 제작하여 챔버에 부착하였고 10 A에서 최대 7 kOe의 고자장을 얻을 수 있어 포화자화가 큰 물질에 대해서도 필요한 자성영역까지 측정이 가능하게 하였다. 또 저온 측정을 위해 SMOKE 샘플 홀더를 개조하여 액체 질소를 이용하여 100 K 근방의 영역에서 온도를 제어할 수 있도록 저온 장치를 구성하였다. 여기에서 샘플 근처에 위차한 e-beam heater가 장착된 고온 부분과 액체 질소 냉각, 온도감지를 위한 센서, cartridge heater가 장착된 저온 부분을 sapphire plate로 분리하여 저온용 cartridge heater의 파손을 최소화하였다. 이러한 SMOKE 시스템을 구성한 후에 우리는 Fe/Cr(001)시스템의 자성특성에 대해 연구하였다. Fe/Cr 시스템은 Fe/Cr/Fe의 exchange coupling이나 bulk Cr의 복잡한 자성 특성 때문에 주목을 받아왔다. 이 연구에서 우리는 저온 및 상온에서 Cr(001) 단결정 위에 증착된 Fe 박막의 자성 특성을 보고한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2758-2764
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• 2015

In the field of electronic warfare applications, high voltage power supply(HVPS) for high power phased array transmitters must necessarily have an independent operating characteristics for driving mini TWTs. TWT independent operational characteristics, in order to run without interrupting the electronic warfare mission by maintaining the partial transmission function even when one of the TWT has occurred a failure, is known to be very important. In this paper, we describe the research on high-speed independent control system using a high-density HVPS, including FE modulators, hardware configuration and the FPGA in order to independently operate mini TWTs. Also, we have simulated some possible faults in phased array transmitters, and presents the test results to control a faulted TWT independently.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.247-259
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• 2009

This study is focused on the relationship between whole rock boron contents and metamorphic P-T conditions of metasedimentary rocks from northeastern Yeongnam massif around Samcheok area, Korea. Metamorphic P-T conditions of sillimanite and garnet zones based on the Ti-biotite geothermometer is 553-687$^{\circ}C$ and 582-722$^{\circ}C$ at 4-6 kbar, respectively. In the metasedimentary rocks, boron contents in whole rock decrease with increasing metamorphic grade, from sillimanite zone (9.60-189 ppm B) to garnet zone (2.63-15.97 ppm B), except one sample (90.9 ppm B) from garnet zone containing graphites. Boron depletion in garnet zone has relation with mode of tourmaline which are broken down with increasing metamorphic temperature. Boron contents are indirectly proportional to major and trace elements such as $Al_2O_3$, MgO, $Fe_2O_3$, $K_2O$, Li, Ba, Sc, Co, Cr, Rb and Cs that are abundant in tourmalines. In conclustion, tourmalines and graphite are modulator of boron contents in metasedimentary rocks. In the biotite granitic gneisses, boron contents (2.62-12.2 ppm B) are similar or lower than those of metasedimentary rocks and have no relation with metamorphic P-T conditions.

• Journal of Food Hygiene and Safety
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• v.13 no.2
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• pp.106-111
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• 1998

This study has been focused on both estrogenic and proliferating activity of genistein (GEN) and bisphenol A (BPA). GEN and BPA enhance the proliferation of estrogen-dependent MCF-7 human breast cancer cells at concentrations as low as 100 nM of GEN and 8 ng/ml of BP A achieving similar effect to that of estradiol at 1 nM. Expression of the estrogen responsive gene, pS2 was also induced in MCF-7 cells by treatment with genistein at dose as low as 1 nM and BPA at dose as low as 4 ng/ml. Using 21 day-old ovariectomized nude mice, we examined end-bud formation and mammary gland development after treatment with bisphenol A or genistein. Compared with untreated control, mammary gland development and end-bud formation were significantly increased in mice fed genistein or bisphenol A (p<0.05). Taken together, it is concluded that GEN and BP A can act as an estrogen agonist resulting in cell proliferation and induction of the estrogen responsive pS2 gene in MCF-7 cells in vitro and in athymic mice in vivo, respectively. Therefore, it is suggested that GEN and BP A might modulate human endocrine system and these compounds might be considered as a endocrine modulator at the low levels of doses.

• Applied Microscopy
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• v.30 no.4
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• pp.347-355
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• 2000

Zinc is one of the most abundant oligoelements in the living cell. It appears tightly bound to some metalloproteins and nucleic acids, loosely bound to some metallothioneins or even as free ion. Small amounts of zinc ions (in the nanomolar range) regulate a plentitude of enzymatic proteins, receptors and transcription factors, thus rolls need accurate homeostasis of zinc ions. Zinc is an essential catalytic or structural element of many proteins, and a signaling messenger that is released by neural activity at many central excitatory synapses. Growing evidences suggest that zinc may also be a key mediator and modulator of the neuronal death associated with transient global ischemia and sustained seizures, as well as perhaps other neurological disease stoles. Some neurons have developed mechanisms to accumulate zinc in specific membrane compartment ('vesicular zinc') which can be evidenced using histochemical techniques. Substances giving a bright colour or emitting fluorescence when in contact with divalent metal ions are currently used to detect them inside cells; their use leads to the so called 'direct' methods. The fixation and precipitation of metal ions as insoluble salt precipitates, their maintenance along the histological process and, finally, their demonstration after autometallographic development are essential steps for other methods, the so called 'indirect methods'. This study is a short report on the autometallograhical approaches for zinc detection in the central nervous system (CNS) by means of a modified selenium method.