• 한국자동차공학회논문집
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• 제24권3호
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• pp.302-309
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• 2016

Urea-SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal $NH_3$ slip. In this study, model based open loop control for urea injection was developed and assessed in the European Transient Cycle (ETC) for heavy duty diesel engine. On the basis of the transient modeling, the kinetic parameters of the $NH_3$ adsorption and desorption are calibrated with the experimental results performed over the zeolite based catalyst. $NH_3$ storage or surface coverage of SCR catalyst can not be measured directly and has to be calculated, which is taken into account as a control parameter in this model. In order to reduce $NH_3$ slip while maintaining NOx reduction, $NH_3$ storage control algorithm was applied to correct the basic urea quantity. If the actual $NH_3$ surface coverage is higher than the maximal $NH_3$ surface coverage, the urea injection quantity is significantly reduced in the ETC cycle. By applying this logic, the resulting $NH_3$ slip peak can be avoided effectively. With optimizing the kinetic parameters based on standard SCR reaction, it suggests that a simplified, less accurate model can be effective to evaluate the capability of model based control in the ETC cycle.

• Smart Structures and Systems
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• 제3권2호
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• pp.189-200
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• 2007

As a functional material, shape memory alloy (SMA) has attracted much attention and research effort to explore its unique properties and its applications in the past few decades. Some of its properties, in particular the electrical resistance (ER) based self-sensing property of SMA, have not been fully studied. Electrical resistance of an SMA wire varies during its phase transformation. This variation is an inherent property of the SMA wire, although it is highly nonlinear with hysteresis. The relationship between the displacement and the electrical resistance of an SMA wire is deterministic and repeatable to some degree, therefore enabling the self-sensing ability of the SMA. The potential of this self-sensing ability has not received sufficient exploration so far, and even the previous studies in literature lack generality. This paper concerns the utilization of the self-sensing property of a spring-biased Nickel-Titanium (Nitinol) SMA actuator for two applications: ER feedback position control of an SMA actuator without a position sensor, and estimation of the opening of a SMA actuated valve. The use of the self-sensing property eliminates the need for a position sensor, therefore reducing the cost and size of an SMA actuator assembly. Two experimental apparatuses are fabricated to facilitate the two proposed applications, respectively. Based on open-loop testing results, the curve fitting technique is used to represent the nonlinear relationships between the displacement and the electrical resistance of the two SMA wire actuators. Using the mathematical models of the two SMA actuators, respectively, a proportional plus derivative controller is designed for control of the SMA wire actuator using only electrical resistance feedback. Consequently, the opening of the SMA actuated valve can be estimated without using an extra sensor.

• Asian-Australasian Journal of Animal Sciences
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• 제20권10호
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• pp.1485-1489
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• 2007

Achaete-scute like 2 (ASCL2) gene encodes a member of the basic helix-loop-helix transcription factor which is essential for the maintenance of proliferating trophoblasts during placental development. ASCL2 gene preferentially expresses the maternal allele in the mouse. However, it escapes genomic imprinting in the human. In this study, the complete open reading frame consisting of 193 amino acids of ASCL2 gene was obtained. Sequence analysis indicated that a C-G mutation existed in the 3' region between Meishan and Large White pigs. The polymorphism was used to determine the monoallelic or biallelic expression with RT-PCR-RFLP in pigs of Large $White{\times}Meishan$ $F_1$ hybrids. Imprinting analysis indicated that the ASCL2 gene expression was biallelic in all the tested tissues (heart, liver, spleen, lung, kidney, stomach, small intestine, skeletal muscle, fat, uterus, ovary and pituitary). PCR-RFLP was used to detect the polymorphism in 270 pigs of the "$Large\;White{\times}Meishan$" $F_2$ resource population. The statistical results showed highly significant associations of the genotypes and fat meat percentage (FMP), lean meat percentage (LMP) and ratio of lean to fat (RLF) (p<0.01), and significant associations of the genotypes and loin eye area (LEA) and internal fat rate (IFR) (p<0.05).

• 대한의용생체공학회:의공학회지
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• 제29권4호
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• pp.323-328
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• 2008

A patient with respiratory disorders such as a sleep apnea is increasing as the obese patient increase on the modern society. Positive Airway Pressure (PAP) devices are used in curing patient with respiratory disorders and turn out to be efficacious for patients of 75%. However, these devices are required for evaluating their performance to improve their performance by the mechanical breathing simulator. Recently, the mechanical breathing simulator was studied by the real time feedback control. However, the mechanical breathing simulator by an open loop control was specially required in order to analyze the effect of flow rate and pressure after operating the breathing auxiliary devices. Therefore the aims of this study were to make the mechanical breathing simulator by a piston motion and a valve function from the characteristic test of valve and motor, and to duplicate the flow rate and pressure profiles of some breathing patterns: normal and three disorder patterns. The mechanical simulator is composed cylinder, valve, ball screw and the motor. Also, the characteristic test of the motor and the valve were accomplished in order to define the relationship between the characteristics of simulator and the breathing profiles. Then, the flow rate and pressure profile of human breathing patterns were duplicated by the control of motor and valve. The result showed that the simulator reasonably duplicated the characteristics of human patterns: normal, obstructive sleep apnea (OSA), mild hypopnea with snore and mouth expiration patterns. However, we need to improve this simulator in detail and to validate this method for other patterns.

• 전력전자학회논문지
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• 제17권3호
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• pp.238-245
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• 2012

This paper presents a sensorless speed control of a 2-phase switch reluctance motor(SRM). The proposed sensorless control scheme is based on the slide mode observer with parameter compensator to improve the estimation performance. In the stand still position, the initial rotor position is determined by pulse current responses of each phase windings and the current difference. In order to determine an accurate initial rotor position, the two initial rotor positions are estimated by the difference of the pulse currents. From the stand still to the operating region, a simple open loop control which determines the commutation sequence by the pulse current of the unexcited phase winding is used. When the motor speed is reached to the sensorless control region, the estimated rotor position and speed by the slide mode observer are used to control the SRM. The flux calculator used in the slide mode observer is designed by phase voltage and the voltage drops in the phase resistance of the winding. The accuracy of the flux calculator is dependent on the phase resistance. For the continuous update of the phase resistance, current gradient at the inductance break point is used in this paper. The error of the estimated rotor position at the current gradient position is used to update the phase resistance to improve the sensorless scheme. The proposed sensorless speed control scheme is verified with a practical compressor used in home appliances. And the results show the effectiveness of the proposed control scheme.

• 한국통신학회논문지
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• 제30권3B호
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• pp.138-143
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• 2005

본 연구는 CDMA2000 시스템에 있어서의 액세스 프로브 알고리즘을 최적화하고자 한다. 이동국이 액세스 채널을 통하여 송신하고 기지국으로부터 ACK 메시지를 받지 못 할 경우 수신신호가 양호한 지역에서는 PWR_STEP 증분값이 1dEm±0.2 값으로 NUM_STEP만큼 증분하여 액세스 프로브를 하게 된다. 그러나 수신신호가 약한 지역에서는 개방루프 전력제어 알고리즘에 따라 송신부 전력 증폭기가 포화상태에 이르게 되어 PWR_STEP 증분값이 0dBm± 0.2값으로 계속해서 액세스 프로브를 하게 되어 이동국 송신에 따른 간섭현상과 배터리 소비전력이 증가하게 된다. 이와 같은 문제를 해결하기 위하여 우리는 수신신호가 강한 지역에서는 IS-95C규격과 같이 RT 슬롯 값만큼 그리고 수신신호가 미약한 지역에서는 RT+1 슬롯 값만큼 지연하여 액세스 프로브 전력 증분값으로 송신하도록 하여 수신세기에 따라 액세스 프로브 알고리즘을 최적화하였다. 시뮬레이션 결과로부터 제안된 알고리즘이 이동국 송신전력에 따른 간섭현상과 소모 전력을 감소시키고 이로 인해 단말기의 총 통화시간을 향상시킬 수 있음을 확인하였다.

• Journal of Ginseng Research
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• 제33권1호
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• pp.59-64
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• 2009

$Ca^{2+}$ and calmodulin (CaM), a key $Ca^{2+}$ sensor in all eukaryotes, have been implicated for defense responses of plants. Eukaryotic CaM contains four structurally and functionally similar $Ca^{2+}$ domains named I, II, III and IV. Each $Ca^{2+}$ binding loop consists of 12 amino acid residues with ligands arranged spatially to satisfy the octahedral symmetry of $Ca^{2+}$ binding. To investigate the altered gene expression and the role of CaM in ginseng plant defense system, cDNA clone containing a CaM gene, designated PgCaM was isolated and sequenced from Panax ginseng. PgCaM, which has open reading frame of 450 nucleotides predicted to encode a precursor protein of 150 amino acid residues. Its sequence shows high homologies with a number of other CaMs, with more similarity to CaM of Daucus carota (AAQ63461). The expression of PgCaM in different P. ginseng organs was analyzed using real time PCR. The results showed that PgCaM expressed at different levels in young leaves, shoots, and roots of 3-week-old P. ginseng. In addition, the expressions of PgCaM under different abiotic stresses were analyzed at different time intervals.

• Nuclear Engineering and Technology
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• 제42권2호
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• pp.203-210
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• 2010

The $\underline{H}igh$ flux $\underline{A}dvanced$ $\underline{N}eutron$ $\underline{A}pplication$ $\underline{R}eact\underline{O}r$ (HANARO), an open-tank-in-pool type reactor, is one of the multi-purpose research reactors in the world. Since the commencement of HANARO's operations in 1995, a significant number of experimental facilities have been developed and installed at HANARO, and continued efforts to develop more facilities are in progress. Owing to the stable operation of the reactor and its frequent utilization, more experimental facilities are being continuously added to satisfy various fields of study and diverse applications. The irradiation testing equipment for nuclear fuels and materials at HANARO can be classified into capsules and the Fuel Test Loop (FTL). Capsules for irradiation tests of nuclear fuels in HANARO have been developed for use under the dry conditions of the coolant and materials at HANARO and are now successfully utilized to perform irradiation tests. The FTL can be used to conduct irradiation testing of a nuclear fuel under the operating conditions of commercial nuclear power plants. During irradiation tests conducted using these capsules in HANARO, instruments such as the thermocouple, Linear Variable Differential Transformer (LVDT), small heater, Fluence Monitor (F/M) and Self-Powered Neutron Detector (SPND) are used to measure various characteristics of the nuclear fuel and irradiated material. This paper describes not only the status of HANARO and the status and perspective of irradiation devices and instrumentation for carrying out nuclear fuel and material tests in HANARO but also some results from instrumentation during irradiation tests.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.502-505
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• 2005

Researches about micro technology travel lively in these days. Such many researches are concentrated in the field of materials and a process field. But properties of micro materials should be known to give results of research developed into still more. In these various material properties, mechanical property such as tensile strength, elastic modulus, etc is the basic property. To measure mechanical properties in micro or nano scale, actuating must be very precise. PZT is a famous actuator which becomes a lot of use to measure very precise mechanical properties in micro research field. But PZT has a nonlinearity which is called as hysteresis. Not precision result is caused because of this hysteresis property in PZT actuator. Therefore feedback control method is used in many researches to prevent this hysteresis of PZT actuator. Feedback control method produce a good result in processing view, but cause a loss in a resolution view. In this paper, hysteresis is compensated by open loop control method. Hysteresis property is modeled in Mathematical function and compensated control input is constructed using inverse function of original data. Reliability of this control method can be confirmed by testing nickel thin film that is used in MEMS material broadly.

• 한국전자파학회논문지
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• 제26권5호
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• pp.463-470
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• 2015

본 논문은 SIR 구조의 피드라인과 공진기를 이용한 새로운 구조의 마이크로스트립 이중대역 대역통과여파기(BPF)를 제안한다. SIR 구조의 피드라인을 이용하여 이중대역 BPF의 두 통과대역 각각에서 입력과 출력 피드라인의 자기장 최대 지점을 서로 일치시켜 공진기와 피드라인 사이의 결합을 최대화하여 여파기 손실을 감소시켰다. 또한, 이중대역 BPF의 제1통과대역 공진기에도 SIR 구조를 적용하여 1) 두 통과대역 사이의 저지대역 특성을 개선시키고, 2) 제2통과대역 공진기와의 결합을 최소화시켜 공진기 간격을 감소시켜 소형화에 기여하였다. 이렇게 하여 이중대역 BPF 통과대역의 중심주파수와 대역폭을 독립적으로 변경시키는 것은 물론, 필터링 성능을 개선하였다. WLAN 규격을 만족하는 이중대역 BPF를 제작하고, 측정 결과와 비교하여 제안한 여파기 설계 방법이 유용하다는 것을 입증하였다.