• 대한방사선기술학회지:방사선기술과학
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• 제30권2호
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• pp.153-159
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• 2007

PACS의 도입에 발맞추어 시작된 digital 의료영상은 현재 방사선 진단 및 치료 영역에서 일반화되었으며 특히 진단영역에서는 눈부신 발전을 거듭하고 있다. 치료영역에서의 digital image 구현은 상대적으로 느린 성장과정을 거쳐 오늘에 이르고 있다. 본 논문은 이러한 analog에서 digital로 변화하는 흐름을 인식하여 정도관리(Quality Assurance) 업무 중 mechanical check 부분을 digital image base 업무로 대체하여 수행하고, 기존의 육면체 또는 사각형틀의 개념을 탈피한 구형(球形)의 Spherical mechanical check device(SMCD) 고안하여 그 실용성을 실험하였다. Source(target)에서 image detecter 간의 거리가 항상 일정하고, Spherical mechanical check device(SMCD)의 중심까지 거리가 일정하다면 어느 방향에서 SMCD를 exposure하더라도 그 크기는 항상 일정하게 영상으로 표현 될 것이다. 이를 위해 정확한 반구(半球)를 2개 정밀 제작하여 그것을 합쳤을 때 정원(正圓)의 구(球)가 되도록 하였다. 이를 이용하여 radiation field와 light field의 일치도, radiation field 크기의 정확도($(5{\times}5,\;10{\times}10,\;15{\times}15\;cm)$), Collimator field 크기의 정확도($5{\times}5,\;10{\times}10,\;15{\times}15\;cm$), Gantry rotation isocenter check, Collimator rotation isocenter check, Room laser accuracy check, Collimator rotation angle check와 Couch rotation angle check 등 기존의 mechanical check를 digital image를 이용하여 실행할 수 있었으며, 기존의 Flat 또는 정육면체 형태의 mechanical check device로는 쉽게 하기 힘든 non-coplanar field에 적용되는 Gantry와 Couch가 동시에 rotation되었을 때 그 isocenter의 일치도를 real time으로 확인할 수 있었다.

• 대한방사선기술학회지:방사선기술과학
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• 제25권1호
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• pp.63-71
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• 2002

The aim of this study Is to develop a simple and fast method which computes in-vivo doses from transmission doses measured doting patient treatment using an ionization chamber. Energy fluence and the dose that reach the chamber positioned behind the patient is modified by three factors: patient attenuation, inverse square attenuation. and scattering. We adopted a straightforward empirical approach using a phantom transmission factor (PTF) which accounts for the contribution from all three factors. It was done as follows. First of all, the phantom transmission factor was measured as a simple ratio of the chamber reading measured with and without a homogeneous phantom in the radiation beam according to various field sizes($r_p$), phantom to chamber distance($d_g$) and phantom thickness($T_p$). Secondly, we used the concept of effective field to the cases with inhomogeneous phantom (patients) and irregular fields. The effective field size is calculated by finding the field size that produces the same value of PTF to that for the irregular field and/or inhomogeneous phantom. The hypothesis is that the presence of inhomogeneity and irregular field can be accommodated to a certain extent by altering the field size. Thirdly, the center dose at the prescription depth can be computed using the new TMR($r_{p,eff}$) and Sp($r_{p,eff}$) from the effective field size. After that, when TMR(d, $r_{p,eff}$) and SP($r_{p,eff}$) are acquired. the tumor dose is as follows. $$D_{center}=D_t/PTF(d_g,\;T_p){\times}(\frac{SCD}{SAD})^2{\times}BSF(r_o){\times}S_p(r_{p,eff}){\times}TMR(d,\;r_{p,eff})$$ To make certain the accuracy of this method, we checked the accuracy for the following four cases; in cases of regular or irregular field size, inhomogeneous material included, any errors made and clinical situation. The errors were within 2.3% for regular field size, 3.0% irregular field size, 2.4% when inhomogeneous material was included in the phantom, 3.8% for 6 MV when the error was made purposely, 4.7% for 10 MV and 1.8% for the measurement of a patient in clinic. It is considered that this methode can make the quality control for dose at the time of radiation therapy because it is non-invasive that makes possible to measure the doses whenever a patient is given a therapy as well as eliminates the problem for entrance or exit dose measurement.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.37-43
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• 2004

The purpose of this study is to develop a practical image inspection system that could recognize it correctly, endowing flexibility to the productive field, although the same object for work will be changed in the size and rotated. In this experiment, it selected a fighter, rotating the direction from $30^{\circ}$ to $45^{\circ}$ simultaneously while changing the size from 1/4 to 1/16, as an object inspection without using another hardware for exclusive image processing. The invariant moments, Hu has suggested, was used as feature vector moment descriptor. As a result of the experiment, the image inspection system developed from this research was operated in real-time regardless of the chance of size and rotation for the object inspection, and it maintained the correspondent rates steadily above from 94% to 96%. Accordingly, it is considered as the flexibility can be considerably endowed to the factory automation when the image inspection system developed from this research is applied to the productive field.

• 한국IT서비스학회지
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• 제11권4호
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• pp.181-194
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• 2012

The one of the most meaningful change in the recent ubiquitous environment is the omnipresence of public digital display device for providing ubiquitous information. It is the important issue to provide publicity as well as adaptive information to each user in the field of the public digital display device. This research proposes the idea ensuring fast response speed by the selection of user preference function. The preference function is selected by statistics using Zipf distribution in the system comprising mobile device and digital display device based on NFC (Near Field Communication). The idea is proved by CPM-GOMS model and the improvement of user response can be achieved.

• 한국산업융합학회 논문집
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• 제26권3호
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• pp.395-400
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• 2023

Recently, the number of hornet is rapidly increasing because of change in the ecological climate. It gives a sense of threat to the people and damages the beekeeping industry as a predator of honey bees. Firefighters are working to remove hornet and vespiary, but it has been reported that it is difficult to remove at high altitudes. In this study, an ultra-light flying device was developed to remove vespiary. It has been developed in four types: Drug spray type, Clamp type, Cutter type, and Scraper type, which can be used as field-customized equipment. Therefore, the developed equipment is expected to contribute to the safe field activities of firefighters.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권6호
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• pp.387-394
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• 2000

This paper presents a method of cold gas flow-field analysis within puffer type GCB(Gas Circuit Breaker). Using this method, the entire interruption process including opening operation of GCB can be simulated successfully. In particular, the distortion problem of the grid due to the movement of moving parts can be dealt with by the fixed grid technique. The gas parameters such as temperature, pressure, density, velocity through the entire interruption process can be calculated and visualized. It was confirmed that the time variation of pressure which was calculated from the application of the method to a model GCB agreed with the experimental one. Therefore it is possible to evaluate the small current interruption capability analytically and to design the interrupter which has excellent interruption capability using the proposed method. It is expected that the proposed method can reduce the time and cost for development of GCB very much. It also will be possible to develop the hot-gas flow-field analysis program by combining the cold-gas flow field program with the arc model and to evaluate the large current interruption capability.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.778-781
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• 2002

MI(Magneto-Impedance) sensor which is made by thin films has significantly high detecting sensitivity in weak magnetic field. It also has a merit to be able to build in the low power system. Its structure is simple, which makes it easier to prepare a miniature. In this study, its magnetic permeability and anisotropy field$(H_k)$ as a function of a thickness of sputtered amorphous CoZrNb films with zero-magnetostriction and excellent soft magnetic property are investigated. In order to make a uniaxial anisotropy, film was subjected to the post annealing in a static magnetic field with 1KOe intensity at 250, 300, and $320^{\circ}C}$ respectively for 2 hours. Anisotropy field$(H_k)$ of film is measured by using a MH loop tracer. Its magnetic permeability of a film is measured over the frequency range from 1 MHz to 750MHz. It has shown that the magnetic permeability of amorphous CoZrNb film is decreased due to the skin effect with increasing a thickness of the CoZrNb film, and hence its driving frequency is lowered. And, it was examined on the permeability and impedance to fabricate the MI sensor which acts at a low frequency by thickening a CoZrNb film relatively.

• 한국환경과학회지
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• 제18권9호
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• pp.941-952
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• 2009

The urban microscale wind field around the air quality monitoring station was investigated in order to check how a building complex influences it. For this study as the high density areas Jwa-dong and Yeonsan-dong monitoring sites in Busan were chosen. As the direction of inflow which is perpendicular to the building of the monitoring station was expected to cause the considerable variation of the wind field, that direction was selected. The model Envi-met was used as the diagnostic numerical model for this study. It is suitable for this investigation because Envi-met has the microscale resolution. After simulating it, on the leeward side around a building complex the decrease of flow velocity and some of vortexes or circulation area were discovered. In addition, on the edge of the top at the building and at the back of the building the upward flow was developed. If the sampling hole of monitoring site were located in this upward flow, it would be under the influence of upward flow from the near street.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.382.1-382.1
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• 2014

Graphene field-effect transistors (GFET) is one of candidates for future high speed electronic devices since graphene has unique electronic properties such as high Fermi velocity (vf=10^6 m/s) and carrier mobility ($15,000cm^2/V{\cdot}s$) [1]. Although the contact property between graphene and metals is a crucial element to design high performance electronic devices, it has not been clearly identified. Therefore, we need to understand characteristics of graphene/metal contact in the GFET. Recently, it is theoretically known that graphene on metal can be doped by presence of interface dipole layer induced by charge transfer [2]. It notes that doping type of graphene under metal is determined by difference of work function between graphene and metal. In this study, we present the GFET fabricated by contact metals having high work function (Pt, Ni) for p-doping and low work function (Ta, Cr) for n-doping. The results show that asymmetric conductance depends on work function of metal because the interfacial dipole is locally formed between metal electrodes and graphene. It induces p-n-p or n-p-n junction in the channel of the GFET when gate bias is applied. In addition, we confirm that charge transfer regions are differently affected by gate electric field along gate length.

• 전자공학회논문지 IE
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• 제46권2호
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• pp.1-6
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• 2009

본 연구에서는 초소형 화의 욕구와 고밀도의 내실을 동시에 충족시킬 수 있으며 전자 장해를 발생하지 않는 일체형 인덕터 코어를 개발하기 위한 방법의 하나로 고전류인가에 따른 인덕터의 전자장 특성을 분석하고자하였다. 분석 결과, 인덕터 내부에서는 전자장이 크게 발생하였지만 인덕터 표면에 나타나는 자장분포 값은 매우 미약하여 주위의 다른 전자 부품에 영향을 미칠 정도는 아니었으며, 표면을 벗어나면 그 값은 순식간에 거의 0[T]로 작아지고 있기 때문에 일체형 인덕터를 이용하여 회로를 구성하였을 때 다른 전자 부품들에 대한 전자 장해는 발생하지 않을 것으로 생각된다. 이 결론은 일체형 인덕터 개발에 많은 영향을 미칠 것이며, 특히 인덕터 코어의 특성 분석 및 신뢰도 향상에 많은 도움이 될 것으로 예상된다.