• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1774-1775
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• 2011

퍼지이론은 비선형적 데이터의 취급에 있어 강력한 수단이 될 수 있으며, 본 논문에서는 퍼지시스템을 인간의 후각을 모사한 GAS 식별 시스템의 설계에 적용하였다. 먼저, 다수의 센서들의 특성 분석에 따라 GA를 이용하여 그룹화를 시킨 후 각각의 그룹들에서 나타나는 데이터들의 특성에 맞게 퍼지시스템을 설계하여, 센서들의 유동적 특성에 따른 조합과 퍼지시스템의 비선형 데이터에 대한 기술능력을 모두 수용할 수 있는 식별 시스템을 설계하였다. 마지막으로 성능 검증을 통해 하나의 퍼지시스템을 선택함으로써, 유동적 특성이 큰 센서들의 성능을 배제할 수 있도록 하여 보다 정확한 식별이 가능하도록 시스템을 설계 하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.7
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• pp.549-555
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• 2015

A measurement technique of interfacial velocity in air-water separated flow by particle tracking velocimetry using an infrared camera (IR-PTV) was developed. As infrared light with wavelength in the range of 3-5 um could hardly penetrate water, IR-PTV can selectively visualize only the tracer particles existing in depths less than 20 um underneath the air-water interface. To validate the measurement accuracy of the IR-PTV technique, a measurement of the interfacial velocity of the air-water separated flow using Styrofoam particles floating in water was conducted. The interfacial velocity values obtained with the two different measurement techniques showed good agreement with errors less than 5%. It was found from the experimental results obtained using the developed technique that with increasing air velocity, the interfacial velocity proportionally increases, likely because of the increased interfacial stress.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.33-37
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• 1993

연결부를 지닌 대형의 노즐형상 제품은 대형산업기기에서 용기의 일부 및 추진체 및 인공위성 발사 대등에서 쓰이는 제품으로 목적하고자 하는 최종 조립품의크기에 따라 제품자체의 지름이 1m 에서 수m 에 이르는 대형으로 제작된다. 대형노즐형 제품은 제품 자체의 강도, 정확한 치수 및 소요재료의 다수등도 중요한 요소이나, 가공하중의 크기에 따라 다르지만 제품을 만들기 위해서는 수만톤을 필요로하기 때문에 제품제조의 가능여부가 성형기의 능력에 의존하게 된다. 본 연구는 비교적 소형장비로써 대형 노즐형단조 품의 제작이 가능한 새로운 성형공정을 개발하는데 그 목적이 있으며 공정개발은 비교적 소형 장비로써 대형단조품의 제작이 가능하도록 하는데 촛점을 맞추고서 이루어 졌다. 이를 위해 여러가지 가능한 방법 들을 제안하고, 각각의 공정 방법들에 대해서 Plasticine 모델 시험을 통하여 소성유동에 의한 성형성과 하중을 검토한 후에 국내에서 사용가능한 장비 및 하중능력, 그리고 성형성 등을 고려하여 적절한 공정방법을 선택하였다. 선택된 공정에서 점진적 팽창단조를 위한 예비 성형체의 결정 및 공정변수의 결정등을 납 모델링실험을 행하여하였으며 실재 재료의 축소모형실험을 수행하여 공정을 확인 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.189-192
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• 2006

무선 네트워크 환경에서의 미디어 전송은 채널의 패이딩 현상 및 채널 잡음 등으로 인한 다량의 패킷손실과 전송지연의 변동으로 급격한 화질 열화를 발생시킨다. 이러한 채널 변동이 심한 무선 네트워크 환경에서 성공적으로 미디어를 전송하기 위해서 FEC (Forward Error Correction), ARQ (Automatic Repeat reQuest) 및 인터리빙을 사용하여 오류를 복구한다. 하지만 각각의 오류제어 모드는 채널 상황 및 오류 패턴에 따라 효율성이 다르기 때문에, 채널 상황에 적응적으로 변경할 수 있는 기법이 필요하다. 본 논문에서는 무선채널 변동을 송 수신측의 피드백 정보를 통해 측정하고 이에 따라 유동적으로 가장 적합한 오류제어 모드를 선택하여 패킷손실을 최소화하는 네트워크 적응형 전송오류제어 기법인 NASTE(Network-Adaptive Selective Transport Error control)를 제안한다. 제안된 기법의 성능을 검증하기 위해 IEEE 802.11g 무선랜 환경에서 NASTE 를 구현해서, MPEG-2 미디어 전송할 때 발생하는 패킷오류를 복구함으로써 전체적인 전송률 개선을 검증한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.3
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• pp.261-266
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• 2019

Flow cytometry is an electrical detection system that provides precise and diverse optical properties to cells and micro particles. Flow cytometry, which provides multidimensional information including cell size and granularity through light scattering and fluorescence emission generated by the induction of light of a specific wavelength to the fluorescently treated cells or micro particles, plays an important role in biomedical and biophysical fields. However, it has some drawbacks such as high cost, size of the instrument and limitation in selecting fluorescent dyes. Therefore, in this paper, a low cost compact fluorescent detection system is developed using light-emitting diode and microcontroller. The proposed fluorescence detection system has a replaceable the light source/fluorescence filter/photodetector and constructed by 3D printer, so that the user can design a customized system according to the selected fluorescent dyes. The fluorescence intensity was measured by varying the number of fluorescently labeled cells, and the measured intensities showed a high linearity within the tested concentration ranges.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8C
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• pp.489-496
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• 2011

Energy efficiency in wireless sensor networks is a principal issue to prolong applications to track the movement of the large-scale phenomena. It is a selective wakeup approach that is an effective way to save energy in the networks. However, most previous studies with the selective wakeup scheme are concentrated on individual objects such as intruders and tanks, and thus cannot be applied for tracking continuous objects such as wild fire and poison gas. This is because the continuous object is pretty flexible and volatile due to its sensitiveness to surrounding circumferences so that movable area cannot be estimated by the just spatiotemporal mechanism. Therefore, we propose a cluster-based algorithm for applying the efficient and more accurate technique to the continuous object tracking in enough dense sensor networks. Proposed algorithm wakes up the sensors in unit cluster where target objects may be diffused or shrunken. Moreover, our scheme is asynchronous because it does not need to calculate the next area at the same time.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1640-1647
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• 1993

The numerical diffusion arising from streamline-to-grid skewness produces a deteriorating effect on the numerical accuracy. The QUICKER scheme to reduce the numerical diffusion requires more computational effort than the HYBRID scheme. This paper deals with the relative computational efficiencies of adopting QUICKER scheme with a coarser grid system and of adopting HYBRID scheme with a denser grid system. Laminar driven cavity flow with Re=400, 1000 is used as a test problem. It is found that QUICKER scheme with a coarser grid system is more efficient than the HYBRID scheme with a denser grid system.

• Clean Technology
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• v.24 no.1
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• pp.63-69
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• 2018

The reduction reaction characteristics and physicochemical properties were studied for the selection of oxygen carrier, which is the core of the chemical looping combustion (CLC) technology. Fuel conversion and $CO_2$ selectivity of oxygen carrier according to the concentration of reducing gas and the reduction temperature using three kinds of oxygen carrier (SDN70, N018-R2, N016-R4) were measured and compared. In addition, Attrition Index (AI) and BET surface area were measured to analyze the attrition resistance and the surface characteristics of the oxygen carrier. As a result, it was confirmed that all three kinds of oxygen carrier were suitable for use in chemical roofing combustion system, and the best particle was determined to be N016-R4.

• Clean Technology
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• v.27 no.1
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• pp.61-68
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• 2021

Selective catalytic reduction (SCR) is widely used as a method of removing nitrogen oxide in large-capacity thermal power generation systems. Uniform mixing of the injected ammonia and the inlet flue gas is very important to the performance of the denitrification reduction process in the catalyst bed. In the present study, a computational analysis technique was applied to the ammonia injection system design process of a denitrification facility. The applied model is the denitrification facility of an 800 MW class coal-fired power plant currently in operation. The flow field to be solved ranges from the inlet of the ammonia injection system to the end of the catalyst bed. The flow was analyzed in the two-dimensional domain assuming incompressible. The steady-state turbulent flow was solved with the commercial software named ANSYS-Fluent. The nozzle arrangement gap and injection flow rate in the ammonia injection system were chosen as the design parameters. A total of four (4) cases were simulated and compared. The root mean square of the NH3/NO molar ratio at the inlet of the catalyst layer was chosen as the optimization parameter and the design of the experiment was used as the base of the optimization algorithm. The case where the nozzle pitch and flow rate were adjusted at the same time was the best in terms of flow uniformity.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.847-849
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• 2002

인공면역시스템에서 중요한 특징중의 하나는 지속적으로 변화하는 환경에서 자기(self)의 유동적인 패턴을 동적으로 학습하고 비자기(non-self)에 대한 새로운 패턴을 예측하는데 있다. 본 논문은 자기적 용(self-adaptation)의 인공면역체계 특성을 기반으로하여 설계된 dynamics(동적 클론선택 알고리즘, dynamic clonal selection algorithm)의 역할을 논한다. 시스템의 세가지 중요한 변수인 자기내성 기간(Tolerisation Period). 연역 반응 임계값(activation threshold). 수명(life span)에 따라 변화하는 dynamics의 성능을 네트워크 침입에서 흔히 발견되는 시나리오를 모의실험하여 평가한다