• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.851-857
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• 2023

The purpose of this study is to investigate the effect of changes in collimation size and sub ROI on exposure index(EI) in hand radiography, present collimation size and EI suitable for average hand size of Koreans, and present the effect of changes in sub ROI on EI. The subjects of this study were hand-wrist phantom, and the exposure conditions were set to 55 kVp, 125, mA, and 6.25 mAs, and source to image receptor distance was applied to 110 cm. Based on the vendor recommended sub-ROI (18.7" × 18.7", 8" × 10", 8" × 7.4", 6" × 7.4")and the textbook's recommended sub-ROI 8" × 10", each obtaining 30 images, and comparing the EI shown in the equipment. The EI according to the change in the size of the collimation were 1663.7±4.52, 8"×10" is 1489.1±4.49, 8"×7.4" is 1716.9±3.00, 6"×7.4" is 168.7±3.66 for each EI, and the average value of each value was statistically significant. The average EI according to the sub ROI change was 1489.1±4.49 for SS, LS was 1694.8±5.19 for AEC, 2052.9±5.96, VR was 1548.3±3.20, and HR was 1663.2±4.33. The appropriate field size considering the hand size of Koreans was found to be 8"×7.4". In addition, when the field size increases based on the generally known field size (8"×10") during hand radiography, the EI value changes from a maximum of 15% to a minimum of 11%, and the sub ROI shape based on sub ROI 'SS' Depending on the change, the EI value increased from a maximum of 37% to a minimum of 3%.

• International Journal of Highway Engineering
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• v.4 no.2 s.12
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• pp.33-42
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• 2002

The cracks in the pavements result from drying shrinkage, temperature change, repeated traffic loadings and so on. The reduction of soil support, spatting and many local failures are caused by water and incompressible foreign materials infiltrated into the cracks. In order to reduce this kind of problems the crack width must be controlled and managed by the accurate measurement. The current method is a visual survey using a microscope, which requires traffic blocking. The purpose of this study is to find the best condition to measure accurate crack width using automated pavement condition survey equipment running at the similar speed as other vehicles. In this study pavement surfaces are filmed on an enlarged scale by the camera with a zoom lens, and then the proper focal distance is determined according to the crack width through a pilot survey. The conditions for measurement of the accurate crack width using the image processing technique are suggested by comparing crack widths surveyed using a microscope in the field with those computed by various factors in the image processing program, STADI-2. In conclusion, the camera with a focal distance of 75m could detect crack range of 0.5mm$\sim$1.2mm In width with an accuracy of 80% for CRCP. The camera with a focal distance of 12.5mm could detect crack range of 1.8mm$\sim$3.3mm in width with an accuracy of 90% for asphalt pavement.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.183-189
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• 2018

This study deals with the design and development of imaging optics having 24mm focal length for MWIR ($3{\sim}5{\mu}m$) with two symmetrical lenses facing each other. We used CodeV in our optical design, and we performed the optimization process to have the resolution and angle of view satisfying the user's requirements. The materials of lenses were limited to two types, including KCIR035 with a refractive index of 1.7589, developed in Korea. The optical system designed in this way consists of two aspherical lenses made of KCIR035 material having the same shape and one spherical lens made of Si. Here, the arrangement of the two aspherical lenses is characterized by having a symmetrical structure facing each other. And this optical system has a resolution of MTF value of 0.35 or more at a line width of 20 lp / mm. Therefore, it is considered that this optical system has the capability to be applied to a thermal imaging camera using a $206{\times}156$ array MWIR detection device having a pixel size of $25{\mu}m$.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.224-230
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• 2013

Laser Lift-Off (LLO) is a process that removes a GaN or AIN thin layer from a sapphire wafer to manufacture vertical-type LEDs. It consists of a light source, an attenuator, a mask, a projection lens and a beam homogenizer. In this paper, we design an attenuator and a projection lens. We use the 'ZEMAX' optical design software for analysis of depth of focus and for a projection lens design which makes $7{\times}7mm^2$ beam size by projecting a beam on a wafer. Using the 'LightTools' lighting design software, we analyze the size and uniformity of the beam projected by the projection lens on the wafer. The performance analysis found that the size of the square-shaped beam is $6.97{\times}6.96mm^2$, with 91.8 % uniformity and ${\pm}30{\mu}m$ focus depth. In addition, this study performs dielectric coating using the 'Essential Macleod' to increase the transmittance of an attenuator. As a result, for 23 layers of thin films, the transmittance total has 10-96% at angle of incidence $45-60^{\circ}$ in S-polarization.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.15-21
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• 2007

In this paper, we propose a technique of a practical symbol acquisition and tracking using a low complex ADC and simple digital circuits for noncoherent asynchronous impulse-radio-based Ultra Wideband (IR-UWB) receiver based on energy detection. Compared to previous approaches of detecting an exact acquisition time that require much hardware resource, the proposed technique is to detect the target symbol by finding the symbol acquisition interval per symbol with a target symbo, thus the complexity of the complete signal processing and power consumption by ADC are reduced. To do this, we define the bit decision window (BDW) and analyze the relation between SNR, hardware resource, size of BDW and BER(Bit Error Rate). Using the results, the optimum BDW size for the minimum BER with limited hardware resource is selected. The proposed synchronization technique is verified with an aid of a simulator programmed by considering practical impulse channels.

• Journal of Korea Spatial Information System Society
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• v.11 no.2
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• pp.79-88
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• 2009

The volume of memory to store real-time data stream is varied dynamically. Continuous queries processing the data stream must manage the storage volume dynamically. In previous research, according to current volume of data a general memory manager which allocates and releases memory by a page unit is researched.However, the method frequently executes page allocation and release to store data stream. Moreover, particularly delayed queries can monopolize many of pages because the method directly allocates pages when a query has not enough memory. Focusing on the problems in memory management systems, this research proposes a memory management method which reduces the frequency of allocation and release and uniformly distributes pages for queries. The method can reduce the frequency of allocation and release through allocation based on utilization ratio of pages in each query and prevent memory monopoly through memory allocation which considers query delay.

• Journal of The Korea Institute of Healthcare Architecture
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• v.17 no.2
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• pp.53-59
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• 2011

본 연구는 미국 텍사스 주의 소도시에 있는 스캇 앤 화이트 클리닉의 외부공간을 대상으로 하여 외래환자와 방문객들이 직면하는 길찾기의 문제점을 분석한다. 연구의 공간적 범위는 클리닉의 외부공간으로 한정하여 진입도로에서 진입하여 주차한 후 출입구에 도달하는 경로에서 관찰되는 행태적 특성을 분석한다. 분석의 초점은 진입도로에서 이루어지는 경로선택의 결정과 그것이 클리닉에 진입하기 위한 출입구 결정에 미치는 영향관계에 둔다. 분석은 외부공간에서의 길찾기에 관한 기존 연구문헌을 참고하여 작성한 연구모형에 의해 이루어진다. 구체적으로 보면, 이용자들이 보이는 날씨, 성별, 그리고 나이에 따른 길찾기 행태의 차이를 클리닉의 남동측 출입구와 남서측 출입구에서 발생하는 이용자들의 하차 빈도를 측정하였다. 또한 하차의 위치를 행태 지도에 기록하여 연구모델에 나타나는 상관성을 분석하였다. 길찾기 행태분석 결과를 통해 파악된 외부주차장에 주차한 후 클리닉에 접근하는 이용자들의 경로선택의 문제점과 클리닉의 입구 공간에서 하차한 이용자들의 입구선택에서 나타나는 문제점을 토대로 하여 외부공간에서 발생하는 길찾기 행위의 효율성을 증진시키기 위한 디자인 추천 사항을 다음과 같이 제시한다: (1) 시각적 단서를 제공하기 위해 남서쪽 출입구의 형태와 색채 차별화; (2) 도로에서 클리닉 진입공간에 위치한 안내판의 글자 크기 확대; (3) 학습된 길찾기 행태를 보조하기 위해 동쪽에 랜드마크 시설물 설치 및 목적 지점의 최종경관 개선; (4) 과도한 클리닉의 정보에 의해 감소되는 가독성을 고려하여 안내판의 정보 간략화; (5) 색채의 대조를 고려(출입구 벽에 설치된 클리닉의 이름이 갈색에 푸른색으로 설치되어 있어 색채의 대비가 낮아 가독성 떨어짐); (6) 클리닉 중앙 출입구의 하차 공간 상부에 설치된 캐노피 기둥의 과도한 크기에 의해 발생하는 가시공간의 감소에 의해 발생하는 하차 공간 사용의 혼잡 문제를 제거하기 위해 기둥규모 축소; (7) 하차점 6까지 캐노피를 확장하여 우천시에 발생하는 공간 사용의 문제점 제거; 그리고 (8) 올바른 하차공간 사용을 위해 진입 접근도로에 차선 설치.

• Journal of Pharmacopuncture
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• v.11 no.2
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• pp.5-12
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• 2008

Objective In this article, we report on the intradermal Alcian blue staining method for tracing the meridians of acupuncture. Methods 1% Alcian blue solution was injected into acupoints by using a 0.5mL insulin syringe with a 31-gauge needle, then the skin was incised and was observed under a stereoscopic microscope. The specimens were examined by using immunohistochemical methods and were observed under a confocal laser scanning microscope. Results A threadlike structure, which was visualized with Alcian blue, existed in dermis layer and proceeded to hypodermis. In this structure, characteristic alignments of rod- shaped nuclei and $1-2{\mu}m$ sized DNA granules were observed. Furthermore, abundant blood capillary plexuses, peripheral nerve endings, and a corpuscle-like structure(about $300{\mu}m$ in diameter) were visualized in the skin tissues of acupoints. Conclusion It was concluded that the specific threadlike and corpuscle-like structures corresponded to superficial Bonghan duct and corpuscle, respectively.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.220-224
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• 2017

In this paper, a method of feeding for the near field beam scanning array antenna with three dimensional focal point has been studied. The conventional array antenna theory is mostly about the far field points. The basic idea is to feed the transmitted signal so that it is in phase at the desired point. In this study, a method is proposed to compensate the phase to have the maximum received power at the point where the measurement point distance is near to the array antenna size. In the proposed method, 11 point source antennas are arrayed in three ways in free space. And the contour map is plotted by calculating the radiation patterns in the three dimensional space and the received signal intensities in the plane within the near space. As a result, it was confirmed that 3 dimensional beam scanning is possible also in the near field of the array antenna.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.508-514
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• 2010

The objective of this work presented here was experimental study of steadystate and cold start exhaust nano-sized particle characteristics from common rail diesel engine. The effect of the diesel oxidation catalyst (DOC) on the particle number reduction was insignificant, however, particle number concentration levels were reduced by 3 orders of magnitude into the downstream of diesel particulate filter (DPF). In high speed and load conditions, natural regeneration of trapped particle occurred inside DPF and it was referable to increase particle number concentration. As fuel injection timing was shifted BTDC $6^{\circ}CA$ to ATDC $4^{\circ}CA$, particle number concentration level was slightly reduced, however particle number and size was increased at ATDC $9^{\circ}CA$. Nucleation type particle reduced and accumulation type particle was increased on EGR condition.