• 멤브레인
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• 제34권2호
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• pp.87-95
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• 2024

최근 연구는 역삼투압(RO), 나노여과(NF) 및 전기투석(ED)과 같은 막 공정에서 고급 용량성 탈이온화(CDI) 및 막 변형(MCDI)을 포함하는 광범위한 담수화 및 수처리 방법을 탐구합니다. 비교 분석은 저염도 시나리오에서 ED의 비용 효율성을 보여주는 반면 하이브리드 시스템(NF-MCDI, RO-NF-MCDI)은 향상된 염 제거 및 에너지 효율성을 보여줍니다. 새로운 이온 분리 방법(NF-CDI, NF-FCDI)은 향상된 효율성과 에너지 절감을 제공합니다. 이러한 연구는 또한 다양한 산업에 특정한 복잡한 폐수를 처리하는 데 있어 이러한 방법의 효율성을 강조합니다. 환경 영향 평가는 시스템 선택의 지속 가능성의 필요성을 강조합니다. 또한 마이크로 제작된 센서를 멤브레인에 통합하면 실시간 모니터링이 가능하여 기술 개발이 진전됩니다. 이러한 연구는 새로운 담수화 및 수처리 기술의 다양성과 가능성을 강조합니다. 이는 효율성 향상, 에너지 사용 최소화, 산업별 문제 해결 및 기존 방법 한계를 능가하는 혁신을 위한 귀중한 통찰력을 제공합니다. 다양한 응용 분야에서 효율성 향상, 환경 영향 최소화 및 적응성 보장에 초점을 맞춘 지속적인 발전으로 지속 가능한 수처리의 미래는 밝습니다.

• 한국의학물리학회지:의학물리
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• 제23권4호
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• pp.219-228
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• 2012

기존의 쐐기(wedge) 필터를 사용하는 접선조사(tangential irradiation) 방식의 일반적인 유방암 방사선치료와 동일한 접선 조사야(filed)를 사용하면서 쐐기 필터를 삽입하는 대신 다엽콜리메터의 움직임을 통해 치료부위의 선량분포를 균일하게 형성토록 하는 접선 세기조절 방사선치료(tangential breast Intensity modulated radiotherapy, T-B IMRT)가 유방암치료에 적용되고 있다. 본 연구에서는 T-B IMRT치료계획에서 계산된 선량분포를 기존의 쐐기 필터를 사용한 일반적인 접선조사 방식의 치료계획과 비교하여 치료표적 및 중요장기에서의 선량분포 측면에서 T-B IMRT의 타당성을 살펴보고, 실제 T-B IMRT치료 빔 조사 시 선량 측정 및 치료계획 결과와의 오차 분석을 통해 선량 분포의 정확도를 확인하고자 하였다. 기존의 쐐기필터를 이용한 접선조사 방식으로 치료한 유방암 환자 15명을 대상으로 T-B IMRT치료계획을 세운 후, 계산된 선량분포를 비교, 분석하였다. T-B IMRT치료계획에서 치료표적 부피 내 선량분포의 균일도가 기존의 쐐기를 사용한 접선조사 방식보다 향상된 결과를 보였으며, 주변의 정상조직과 중요장기의 선량을 상대적으로 줄일 수 있음을 확인할 수 있었다. T-B IMRT의 실제 치료조사 시 선량정확도를 분석하기 위해 적합한 팬텀을 사용하여 품질보증(QA) 치료계획을 수립하였다. 원기둥 형태의 아크릴에 이온전리함을 삽입한 형태의 팬텀을 사용하여 치료계획과 실제 치료 빔 조사를 통해 측정된 절대선량 값을 비교하였으며, 평균 오차는 $0.7{\pm}1.4%$로 분석되었다. 이차원 다이오드 검출기 배열장치를 이용한 선량분포의 정확도 분석에서는 치료계획 시 계산된 선량분포와 실제 측정된 선량분포의 gamma evaluation (3%, 3 mm 기준)를 통해 평균 $97.3{\pm}2.9%$의 합격률(pass rate)로 타당성 있는 정확도를 보여주었다. 본 연구를 통해 선량분포 측면에서 기존 쐐기필터를 이용한 접선 조사방식의 방사선치료 대비 T-B IMRT의 장점을 확인할 수 있었고, T-B IMRT에 적합하게 수립된 품질보증 과정을 통해 실제 조사되는 선량의 정확도를 확인할 수 있었다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1992년도 춘계학술대회
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• pp.27-47
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• 1992

Engineers have developed new instruments that aid in diagnosis and therapy Ultrasonic imaging has provided a nondamaging method of imaging internal organs. A complex transducer emits ultrasonic waves at many angles and reconstructs a map of internal anatomy and also velocities of blood in vessels. Fast computed tomography permits reconstruction of the 3-dimensional anatomy and perfusion of the heart at 20-Hz rates. Positron emission tomography uses certain isotopes that produce positrons that react with electrons to simultaneously emit two gamma rays in opposite directions. It locates the region of origin by using a ring of discrete scintillation detectors, each in electronic coincidence with an opposing detector. In magnetic resonance imaging, the patient is placed in a very strong magnetic field. The precessing of the hydrogen atoms is perturbed by an interrogating field to yield two-dimensional images of soft tissue having exceptional clarity. As an alternative to radiology image processing, film archiving, and retrieval, picture archiving and communication systems (PACS) are being implemented. Images from computed radiography, magnetic resonance imaging (MRI), nuclear medicine, and ultrasound are digitized, transmitted, and stored in computers for retrieval at distributed work stations. In electrical impedance tomography, electrodes are placed around the thorax. 50-kHz current is injected between two electrodes and voltages are measured on all other electrodes. A computer processes the data to yield an image of the resistivity of a 2-dimensional slice of the thorax. During fetal monitoring, a corkscrew electrode is screwed into the fetal scalp to measure the fetal electrocardiogram. Correlations with uterine contractions yield information on the status of the fetus during delivery To measure cardiac output by thermodilution, cold saline is injected into the right atrium. A thermistor in the right pulmonary artery yields temperature measurements, from which we can calculate cardiac output. In impedance cardiography, we measure the changes in electrical impedance as the heart ejects blood into the arteries. Motion artifacts are large, so signal averaging is useful during monitoring. An intraarterial blood gas monitoring system permits monitoring in real time. Light is sent down optical fibers inserted into the radial artery, where it is absorbed by dyes, which reemit the light at a different wavelength. The emitted light travels up optical fibers where an external instrument determines O2, CO2, and pH. Therapeutic devices include the electrosurgical unit. A high-frequency electric arc is drawn between the knife and the tissue. The arc cuts and the heat coagulates, thus preventing blood loss. Hyperthermia has demonstrated antitumor effects in patients in whom all conventional modes of therapy have failed. Methods of raising tumor temperature include focused ultrasound, radio-frequency power through needles, or microwaves. When the heart stops pumping, we use the defibrillator to restore normal pumping. A brief, high-current pulse through the heart synchronizes all cardiac fibers to restore normal rhythm. When the cardiac rhythm is too slow, we implant the cardiac pacemaker. An electrode within the heart stimulates the cardiac muscle to contract at the normal rate. When the cardiac valves are narrowed or leak, we implant an artificial valve. Silicone rubber and Teflon are used for biocompatibility. Artificial hearts powered by pneumatic hoses have been implanted in humans. However, the quality of life gradually degrades, and death ensues. When kidney stones develop, lithotripsy is used. A spark creates a pressure wave, which is focused on the stone and fragments it. The pieces pass out normally. When kidneys fail, the blood is cleansed during hemodialysis. Urea passes through a porous membrane to a dialysate bath to lower its concentration in the blood. The blind are able to read by scanning the Optacon with their fingertips. A camera scans letters and converts them to an array of vibrating pins. The deaf are able to hear using a cochlear implant. A microphone detects sound and divides it into frequency bands. 22 electrodes within the cochlea stimulate the acoustic the acoustic nerve to provide sound patterns. For those who have lost muscle function in the limbs, researchers are implanting electrodes to stimulate the muscle. Sensors in the legs and arms feed back signals to a computer that coordinates the stimulators to provide limb motion. For those with high spinal cord injury, a puff and sip switch can control a computer and permit the disabled person operate the computer and communicate with the outside world.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.

• 한국통신학회논문지
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• 제27권12C호
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• pp.1288-1298
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• 2002

타원곡선 암호시스템을 GF(2$^{m}$ )상에서 고속으로 구현하기 위해서는 빠른 나눗셈기가 필요하다. 빠른 나눗셈 연산을 위해선 비트-패러럴 구조가 적합하나 타원곡선 암호시스템이 충분한 안전도를 가지기 위해서는 m의 크기가 최소한 163보다 커야 한다. 즉 비트-패러럴 구조는 0(m$^2$)의 면적 복잡도를 가지기 때문에 이러한 응용에는 적합하지 않다. 따라서, 본 논문에서는 CF(2$^{m}$ )상에서 표준기저 표기법을 사용하여 모듈러 나눗셈 A(x)/B(x) mod G(x)를 고속으로 수행하는 새로운 비트-시리얼 시스톨릭 나눗셈기를 제안한다. 효율적인 나눗셈기 구조를 얻기 위해, 새로운 바이너리 최대공약수(GCD) 알고리즘을 유도하고, 이로부터 자료의존 그래프를 얻은 후, 비트-시리얼 시스톨릭 나눗셈기를 설계한다. 본 논문에서 제안한 나눗셈기는 0(m)의 시간 및 면적 복잡도를 가지며, 연속된 입력 데이터에 대하여, 초기 5m-2 사이클의 지연 후, m 사이클 마다 나눗셈의 결과를 출력한다. 제안된 나눗셈기를 동일한 입출력 구조를 가지는 기존의 연구 결과들과 비교 분석한 결과 칩 면적 및 계산 지연시간 모두에 있어 상당한 개선을 보인다. 따라서 제안된 나눗셈기는 적은 하드웨어를 사용하면서 고속으로 나눗셈 연산을 수행할 수 있기 때문에 타원곡선 암호화시스템의 나눗셈 연산기로 매우 적합하다. 또한 제안한 구조는 기약 다항식(irreducible polynomial) 선택에 있어 어떤 제약도 두지 않고, 단 방향의 신호흐름을 가지면서, 매우 규칙적이기 때문에 필드 크기 m에 대해 높은 유연성 및 확장성을 제공한다.였다. an extraction system, a new optical nonlinear joint transform correlator(NJTC) is introduced to extract the hidden data from a stego image in real-time, in which optical correlation between the stego image and each of the stego keys is performed and from these correlation outputs the hidden data can be asily exacted in real-time. Especially, it is found that the SNRs of the correlation outputs in the proposed optical NJTC-based extraction system has been improved to 7㏈ on average by comparison with those of the conventional JTC system under the condition of having a nonlinear parameter less than k=0.4. This good experimental results might suggest a possibility of implementation of an opto-digital multiple information hiding and real-time extracting system. 촉각에 있는 지각신경세포가 뇌의 촉각엽으로 뻗어 들어가 위의 5가지 신경연접중 어느 형을 형성하는지를 관찰하기 위하여 좌측 촉각의

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.975-976
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• 1993

This talk presents the overview of the author's research and development activities on fuzzy inference hardware. We involved it with two distinct approaches. The first approach is to use application specific integrated circuits (ASIC) technology. The fuzzy inference method is directly implemented in silicon. The second approach, which is in its preliminary stage, is to use more conventional microprocessor architecture. Here, we use a quantitative technique used by designer of reduced instruction set computer (RISC) to modify an architecture of a microprocessor. In the ASIC approach, we implemented the most widely used fuzzy inference mechanism directly on silicon. The mechanism is beaded on a max-min compositional rule of inference, and Mandami's method of fuzzy implication. The two VLSI fuzzy inference chips are designed, fabricated, and fully tested. Both used a full-custom CMOS technology. The second and more claborate chip was designed at the University of North Carolina(U C) in cooperation with MCNC. Both VLSI chips had muliple datapaths for rule digital fuzzy inference chips had multiple datapaths for rule evaluation, and they executed multiple fuzzy if-then rules in parallel. The AT & T chip is the first digital fuzzy inference chip in the world. It ran with a 20 MHz clock cycle and achieved an approximately 80.000 Fuzzy Logical inferences Per Second (FLIPS). It stored and executed 16 fuzzy if-then rules. Since it was designed as a proof of concept prototype chip, it had minimal amount of peripheral logic for system integration. UNC/MCNC chip consists of 688,131 transistors of which 476,160 are used for RAM memory. It ran with a 10 MHz clock cycle. The chip has a 3-staged pipeline and initiates a computation of new inference every 64 cycle. This chip achieved an approximately 160,000 FLIPS. The new architecture have the following important improvements from the AT & T chip: Programmable rule set memory (RAM). On-chip fuzzification operation by a table lookup method. On-chip defuzzification operation by a centroid method. Reconfigurable architecture for processing two rule formats. RAM/datapath redundancy for higher yield It can store and execute 51 if-then rule of the following format: IF A and B and C and D Then Do E, and Then Do F. With this format, the chip takes four inputs and produces two outputs. By software reconfiguration, it can store and execute 102 if-then rules of the following simpler format using the same datapath: IF A and B Then Do E. With this format the chip takes two inputs and produces one outputs. We have built two VME-bus board systems based on this chip for Oak Ridge National Laboratory (ORNL). The board is now installed in a robot at ORNL. Researchers uses this board for experiment in autonomous robot navigation. The Fuzzy Logic system board places the Fuzzy chip into a VMEbus environment. High level C language functions hide the operational details of the board from the applications programme . The programmer treats rule memories and fuzzification function memories as local structures passed as parameters to the C functions. ASIC fuzzy inference hardware is extremely fast, but they are limited in generality. Many aspects of the design are limited or fixed. We have proposed to designing a are limited or fixed. We have proposed to designing a fuzzy information processor as an application specific processor using a quantitative approach. The quantitative approach was developed by RISC designers. In effect, we are interested in evaluating the effectiveness of a specialized RISC processor for fuzzy information processing. As the first step, we measured the possible speed-up of a fuzzy inference program based on if-then rules by an introduction of specialized instructions, i.e., min and max instructions. The minimum and maximum operations are heavily used in fuzzy logic applications as fuzzy intersection and union. We performed measurements using a MIPS R3000 as a base micropro essor. The initial result is encouraging. We can achieve as high as a 2.5 increase in inference speed if the R3000 had min and max instructions. Also, they are useful for speeding up other fuzzy operations such as bounded product and bounded sum. The embedded processor's main task is to control some device or process. It usually runs a single or a embedded processer to create an embedded processor for fuzzy control is very effective. Table I shows the measured speed of the inference by a MIPS R3000 microprocessor, a fictitious MIPS R3000 microprocessor with min and max instructions, and a UNC/MCNC ASIC fuzzy inference chip. The software that used on microprocessors is a simulator of the ASIC chip. The first row is the computation time in seconds of 6000 inferences using 51 rules where each fuzzy set is represented by an array of 64 elements. The second row is the time required to perform a single inference. The last row is the fuzzy logical inferences per second (FLIPS) measured for ach device. There is a large gap in run time between the ASIC and software approaches even if we resort to a specialized fuzzy microprocessor. As for design time and cost, these two approaches represent two extremes. An ASIC approach is extremely expensive. It is, therefore, an important research topic to design a specialized computing architecture for fuzzy applications that falls between these two extremes both in run time and design time/cost. TABLEI INFERENCE TIME BY 51 RULES {{{{Time }}{{MIPS R3000 }}{{ASIC }}{{Regular }}{{With min/mix }}{{6000 inference 1 inference FLIPS }}{{125s 20.8ms 48 }}{{49s 8.2ms 122 }}{{0.0038s 6.4㎲ 156,250 }} }}