• Journal of radiological science and technology
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• v.33 no.1
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• pp.31-36
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• 2010

Low energy high resolution (LEHR) collimator is the most widely used collimator in SPECT imaging. LEHR has an advantage in terms of image resolution but has a difficulty in acquiring high sensitivity due to the narrow hole size and long septa height. Throughput in SPECT can be improved by increasing counts per second with the use of high sensitivity collimators. The purpose of this study is to develop a system model in iterative image reconstruction to recover the resolution degradation caused by high sensitivity collimators with bigger hole size. We used fan-beam model instead of parallel-beam model for calculation of detection probabilities to accurately model the high sensitivity collimator with wider holes. In addition the weight factors were calculated and applied onto the probabilities as a function of incident angle of incoming photons and distance from source to the collimator surface. The proposed system model resulted in the equivalent performance with the same counts (i.e. in shortened acquisition time) and improved image quality in the same acquisition time. The proposed method can be effectively applied for resolution improvement of pixel collimator of next generation solid state detectors.

• Progress in Medical Physics
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• v.6 no.2
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• pp.13-19
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• 1995

The behavior of the correction factor associated with the collimator opening(head-scatter factor) were investigated for the 6MV x-ray beams of medical linear accelerator. The primary photon fluence was measured in air quasi-small fied size. Consideration in this study was given to the effect of head scatter factor with quasi-small fied size, the upper and lower collimator jaw scatter collection factors of quasi-small field (4-10cm) were measured with ion chamber. In general, the wedge factors which are used clinical practics are ignored of dependency on field sizes and depth. In wedge factors for each wedge filter were measured at various depth by using 6MV X-ray. In this present we inverstigated systematically the depth and field sizes dependency to determine the absorbed dose more accurately. Head scatter(upper-lower collimator jaw)appears to be (1) a small effect, less than 5％ over the range of clinical field sizes (2) generated primarily at the flattening filter and therefored influenced most by the upper collimator setting.

• Korean Journal of Microbiology
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• v.45 no.3
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• pp.233-238
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• 2009

The expression of Corynebacterium ammoniagenes purF was analyzed by utilizing a plasmid carrying a cat gene fused to the purF promoter region. Adenine and guanine repressed the expression of the purF gene by 20~30% but hypoxanthine did not exert such repressive effect. The expression purF was maximal at the late log phase and remained constant throughout the stationary phase. Promoter $P_{180}$ which was developed in C. glutamicum was also functional in C. ammoniagenes, achieving maximal activity at the late log phase. The promoter outperformed Escherichia coli $P_{tac}$ promoter by 40~50% level. DNA-affinity purification identified a protein which could bind to the promoter region of the purF gene. The protein showed high similarity to the CRP-family transcriptional regulator encoded by NCgl0120 in C. glutamicum. The size of the screened protein agreed with the expected protein size from the ORF NCgl0120. The corresponding gene in C. ammoniagenes encoded a 42 kDa polypeptide composed of 400 amino acids with expected pI of 4.9. The encoded protein showed 14.1% and 15.8% identity with E. coli and Bacillus subtilis PurR, respectively, suggesting that the isolated protein might be a novel type of regulatory protein involved in the regulation of purine metabolism.

• Progress in Medical Physics
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• v.23 no.3
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• pp.162-168
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• 2012

In proton therapy, in vivo dose verification is one of the most important parts to fully utilize characteristics of proton dose distribution concentrating high dose with steep gradient and guarantee the patient safety. Currently, in order to image the proton dose distribution, a prompt gamma distribution detection system, which consists of an array of multiple CsI(Tl) scintillation detectors in the vertical direction, a collimator, and a multi-channel DAQ system is under development. In the present study, the optimal design of prompt gamma distribution detection system was studied by Monte Carlo simulations using the MCNPX code. For effective measurement of high-energy prompt gammas with enough imaging resolution, the dimensions of the CsI(Tl) scintillator was determined to be $6{\times}6{\times}50mm^3$. In order to maximize the detection efficiency for prompt gammas while minimizing the contribution of background gammas generated by neutron captures, the hole size and the length of the collimator were optimized as $6{\times}6mm^2$ and 150 mm, respectively. Finally, the performance of the detection system optimized in the present study was predicted by Monte Carlo simulations for a 150 MeV proton beam. Our result shows that the detection system in the optimal dimensions can effectively measure the 2D prompt gamma distribution and determine the beam range within 1 mm errors for 150 MeV proton beam.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.32-37
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• 2008

Satellite communication systems including the DVB-S2 (Digital Video Broadcasting - Satellite Version 2) system require operations under low signal-to-noise ratio (SNR) and large frequency offset values, and the initial frame synchronization process necessitates a robust correlation method. While a variety of conventional correlation structures exist for the initial synchronization, each method has different characteristics and performance in different channel environments. In this paper, we propose new correlation methods which exhibit enhanced performance in low SNR and large frequency offsets, and analyze their performance. The proposed methods use the magnitude sum and vector sum of extended differential correlation values, to maximize the correlation between the received signal and the synchronization sequence by using the spanned differential correlation result. The magnitude sum correlation method has better performance compared to conventional methods including the approximated ML (Maximum likelihood) method for SNR values below 4 dB with or without frequency offsets. The vector sum correlation method has improved performance over the magnitude sum method for channels with relatively small frequency offsets.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.438-443
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• 2002

본 연구는 수도작에서 토양과 식물체의 분광반사특성과 영상처리를 이용한 기계시각 잡초검출 센서를 개발하기 위한 기초연구로서 분류하고자 하는 대상체들의 분광반사율을 조사하여 주요한 파장을 선정하고 선정된 파장을 이용한 판별분석을 통해 각 대상체에 대한 분류 정확도를 중심으로 잡초검출 가능성을 조사하기 위하여 수행하였으며, 실험으로부터 얻은 결론은 다음과 같다. 1. 토양과 식물체를 구분하는데 효과적인 파장은 마른 토양의 경우 680 nm, 배수 토양에 있어서는 810 nm로 선정하였고, 토양을 배제한 후 벼와 잡초를 구분하기에 효과적인 파장은 580, 680 nm로 선정하였다. 2. 토양과 식물체를 구분하기 위한 판별분석 결과 2가지 토양상태 모두 식물체와 완전히 구분 가능한 것으로 나타났다. 벼와 잡초를 구분하기 위한 실험에서, 벼는 98%의 분류정확도로 구분이 가능하였고, 잡초는 83%의 분류정확도로 구분이 되는 것으로 나타났다. 따라서 차후 분광학적 원리를 이용한 센서를 제작할 때 본 연구에서 선택한 주요 파장과 판별함수를 이용하여 장치를 구성하고 알고리즘을 제작한다면 벼, 잡초, 토양을 효과적으로 구분이 가능할 것으로 판단되었다. 3. 컬러 CCD 카메라를 사용하는 경우에 있어 식물체와 토양을 구분하기 위해 3 종의 파장 중 630 nm 파장만의 이용을 고려하여 그 분류성능을 분석한 결과, 식물체와 토양은 소수의 관측치를 제외하고 완전히 구분이 가능했고, 벼와 잡초를 구분한 결과에서는 비교적 높은 분류능력을 가진 것으로 나타나 차후 컬러 CCD 카메라를 이용하여 장치를 구성하는데 좋은 기초가 될 것으로 판단된다. 배양체의 접종작업은 모든 배양실이 인력에 의존하였으며, 배양체를 배지와 분리하여 불필요한 부분을 제거하고 배양작물에 따라 생육정도를 2~3등급으로 구분하여 배양용기의 배지 위에 치상하는 과정으로 수행되었으며, 작업능률은 호접란의 경우 배양병에 25본을 접종하는데 시간당 6병, 심비디움은 원형 플라스크에 25본을 접종하는데 시간당 10병 정도였다. 바. 식물체의 대량증식에 사용되는 플라스크, 배양병, PE용기 등 배양용기의 세척작업은 농원의 1개배양실에서 간이식 세척기, 이 외의 9개배양실은 모두 물에 담겨 두었다가 세제와 브러쉬 등을 사용하여 인력으로 세척하고 있어 생력화 기술개발이 요구되었다.도가 빠를수록 건조속도가 빨라졌으며, 건조에너지도 1,334kcal/kg.water로 비슷하게 소요되었다. 마. 시험구와 대비구의 건감률은 시험구에서 1.08~1.36w.b./h로 나타나 대비구보다 약 9.9~18.3%가 높게 나타났고, 건조에너지는 10.2~14.6%가 절감되었다. 발아율은 열풍온도가 낮을수록 높게 나타났고 시험구가 대비구보다 발아율이 낮게 나타났으며, 동할률 증가량도 원적외선.열풍 복합건조방법이 높게 나타나 이것은 곡물 표면에 원적외선 방사에의한 복사열이 전달되어 열장해를 받았기 때문으로 판단되며, 금후 더 연구하여 적정 열풍온도 및 방사체 크기를 구명해야 할 것이다.으로 보여진다 따라서 옻나무 유래 F는 포유동물의 생식기능에 중요하게 작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을

• Korean Journal of Optics and Photonics
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• v.29 no.3
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• pp.110-118
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• 2018

We have designed a mid-infrared optical system for an airborne electro-optical targeting system. The mid-IR optical system is a dual-field-of-view (FOV) optics for an airborne electro-optical targeting system. The optics consists of a beam-reducer, a zoom lens group, a relay lens group, a cold stop conjugation optics, and an IR detector. The IR detector is an f/5.3 cooled detector with a resolution of $1280{\times}1024$ square pixels, with a pixel size of $15{\times}15{\mu}m$. The optics provides two stepwise FOVs ($1.50^{\circ}{\times}1.20^{\circ}$ and $5.40^{\circ}{\times}4.23^{\circ}$) by the insertion of two lenses into the zoom lens group. The IR optical system was designed in such a way that the working f-number (f/5.3) of the cold stop internally provided by the IR detector is maintained over the entire FOV when changing the zoom. We performed two analyses to investigate thermal effects on the image quality: athermalization analysis and Narcissus analysis. Athermalization analysis investigated the image focus shift and residual high-order wavefront aberrations as the working temperature changes from $-55^{\circ}C$ to $50^{\circ}C$. We first identified the best compensator for the thermal focus drift, using the Zernike polynomial decomposition method. With the selected compensator, the optics was shown to maintain the on-axis MTF at the Nyquist frequency of the detector over 10%, throughout the temperature range. Narcissus analysis investigated the existence of the thermal ghost images of the cold detector formed by the optics itself, which is quantified by the Narcissus Induced Temperature Difference (NITD). The reported design was shown to have an NITD of less than $1.5^{\circ}C$.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.226-233
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• 2013

In this study, In Laver's automatic drying device, laver thickness measurement and control devices that are associated with. Disconnect the water and steam, after put a certain amount of the mixture(water and laver) in the mold. In process, Laver of the size and thickness (weight) to determine, constant light source to detect and image LED Lamp occur Vision Sensor (Camera) prepare, then the values of these state of the image is transmitted in real time embedded computers. Built-in measurement and control with the purpose of the application of each of the channels separately provided measurements are displayed on a monitor, And servo signals sent to each of the channels and it become so set function should be. In this paper, the laver drying device, prior to the laver thickness measurement and control devices that rely on the experience of existing workers directly laver manually adjust the thickness of the lever, but the lever by each channel relative to the actuator by installing was to improve the quality. In addition, The effect of productivity gains and labor savings are.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.17-25
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• 2013

The thermotolerant methylotrophic yeast Hansenula polymorpha is an attractive model organism for various fundamental studies, such as the genetic control of enzymes involved in methanol metabolism, peroxisome biogenesis, nitrate assimilation, and resistance to heavy metals and oxidative stresses. In addition, H. polymorpha has been highlighted as a promising recombinant protein expression host, especially due to the availability of strong and tightly regulatable promoters. In this study, we investigated the possibility of employing human serum albumin (HSA) as the fusion tag for the secretory expression of heterologous proteins in H. polymorpha. A set of four expression cassettes, which contained the methanol oxidase (MOX) promoter, translational HSA fusion tag, and the terminator of MOX, were constructed. The expression cassettes were also designed to contain sequences for accessory elements including His8-tag, $2{\times}(Gly_4Ser_1)$ linkers, tobacco etch virus protease recognition sites (Tev), multi-cloning sites, and strep-tags. To determine the effects of the size of the HSA fusion tag on the secretory expression of the target protein, each cassette contained the HSA gene fragment truncated at a specific position based on its domain structure. By using the Green fluorescence protein gene as the reporter, the properties of each expression cassette were compared in various conditions. Our results suggest that the translational HSA fusion tag is an efficient tool for the secretory expression of recombinant proteins in H. polymorpha.

• 대한공업교육학회지
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• v.34 no.2
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• pp.331-345
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• 2009

In this research Sagnac interferometer three different types of mandrel are suggested and this fiber optic sensor is using in monitoring of electric transformer. Vibration characteristics of those mandrels were analyzed and finally more sensitivity mandrel are suggested. Three different mandrels using in fiber optic sensor are hollow cylinder with outer bump, pure hollow cylinder, hollow cylinder with inner bump. Natural frequencies and mode shapes are investigated using finite element method. Mode shape are considered at the frequency range from 2 kHz to 20 kHz. Fundamental dimensions of the hollow cylinder type's mandrel are 30 mm in outer diameter, 50 mm in length, 1 mm in cylinder thickness, $2mm{\times}2mm$ in bump size. Based on the finite element results, when the outer acoustic frequency is near 11 kHz outer bump type and hollow cylinder can get higher sensitivity. Near 17 kHz outer bump and inner bump mandrel can get higher sensitivity. Near 20 kHz hollow cylinder and inner bump mandrel is useful. This results can be applied to design of fiber optic sensor using in monitoring the electrical transformer. Several MHz of outer acoustic frequency can be easily detected using more sensitive mandrel in pursuing expand this technique.