• Ocean and Polar Research
• /
• 제36권2호
• /
• pp.189-197
• /
• 2014

The pearl-spot damsel, Chromis notata, is one of the important fishery species in Korea. While C. notata has been commonly harvested in southern Korea, the increasing number of C. notata in higher latitudes has crucial ecological, economic and evolutionary implications under conditions where the climate is rapidly changing. Here we examined the morphological and genetic characteristics of C. notata to assess patterns of geographical variations among the groups from three different sites. The groups were clearly distinguishable in the analysis of morphological characteristics. On the other hand, the groups were genetically indistinguishable. All individuals fell within a single clade in the neighbor-joining tree but appeared scattered in the haplotype network. Several haplotypes are shared among the sampling sites (Jejudo-Ulleungdo; Hap 9, Wangdolcho-Ulleungdo; Hap 28, Hap 33, Hap 34). Although control region markers did not elucidate the spatial patterns in genetic characteristics, Wangdolcho and Ulleungdo groups appear to exhibit a more robust gene flow between the two groups than with Jejudo group. Integrative approaches such as those combining morphological and genetic analyses minimize potential errors caused by limited perspectives of each analysis and can provide useful information for discovering functional DNA regions attributable to morphological characteristics expressions.

• Journal of Biosystems Engineering
• /
• 제22권4호
• /
• pp.469-478
• /
• 1997

This study was conducted to develop an automatic nutrient-solution mixing system for small-scale sewers. The nutrient-solution mixing system consisted of a low-cost and precise metering device and data acquisition ＆ control system with a personal computer. and, the metering device was composed of three parts those were supply pumps, metering cylinders and venturi tube. The system controlled electric conductivity(EC) and pH of nutrient-solution based on the time-based feedback control method with the information about temperature, EC, and pH of the nutrient-solution. The performance of the nutrient-solution mixing system was evaluated through the control of EC and pH while compared with those of commercial system. Also an experimental cultivation of tomato was conducted to verify and to improve the developed system. Results of this study were as follows. 1. The correlation coefficient of meteing device between the flow rate and operating time was 0.9999, and the linear reuession equation computed was y=21.759x, where y is the discharge($g$) and x is the operating time(s). 2. Calculated errors for the developed metering device and two commercial pump were $\pm$0.3% $\pm$2.45% and $\pm$1.38 % FS error respectively. 3. An automatic nutrient-solution mixing system based on a low-cost and precise metering device was developed. 4. The full scale errors of the developed system in controlling EC and pH at 23$\pm$1$^{\circ}C$ were $\pm$0.05mS/cm and $\pm$0.2, respectively 5. When using the commercial system, the controlled values of EC and pH of the 500 $\ell$ of water were 1.29 mS/cm and 6.1 pH for the setting points of 1.4 mS/cm and 6.0 pH respectively at 23$pm1^{\circ}C$. 6. The developed nutrient-solution control system showed $\pm$0.05 ms/cm of deviation from the setting EC value over the experimental cultivation period. 7. The deviation from the average values of Ca and Mg mass content in the several nutrient-solution were 0.5% and 1.8% respectively.

• 한국추진공학회지
• /
• 제22권5호
• /
• pp.107-114
• /
• 2018

한국형발사체 (KSLV-II) 발사대시스템 상세설계의 산화제 충전 운용 설계를 검증하고자, 나로호 1차 비행 시험 실증 자료과 설계 모델링 유동 해석 결과를 비교하였다. 최대 공급유량에 대비한 유량 비율로 충전 모드별 측정 및 계산값을 비교할 때, 모든 오차는 6.7% 이내이다. 산화제 공급 펌프 후단 및 유량조절 밸브 전단 압력 오차는 5.1% 이내이다. 발사체 공급 전단 최종 압력은 모든 충전 모드에서 실험값의 범위에 포함되는 것을 확인하였다.

• 한국산학기술학회논문지
• /
• 제11권5호
• /
• pp.1646-1652
• /
• 2010

무선 센서 네트워크에서의 통신은 여러 계층으로 나뉘어 각 계층별 역할을 수행하므로 무선통신이 가능할 수 있다. 센서 네트워크에서의 통신계층 중 하나인 MAC(Medium Access Control)계층은 데이터의 에러, 흐름을 제어하고 자원을 관리하기 위해서 사용되며 MAC Protocol을 사용하여 센서 노드간의 통신을 보장한다. 본 논문에서는 에너지 효율성 측면을 강조한 S-MAC. T-MAC 프로토콜의 문제점을 알아보고 SYNC 패킷에 RTS 패킷이 추가된 기법을 이용하여 컨트롤 패킷 전송 시간동안 꼭 필요한 노드만 컨트롤 패킷을 송수신하고, 나머지 노드들은 Sleep 함으로써, 모든 노드가 깨어있는 시간을 효율적으로 줄여 에너지 효율성을 강조하였다. SYNC+RTS 패킷을 보내고 패킷을 받는 노드는 순간 자신이 이번 주기 동안 깨어 있을 필요가 없음을 알고 바로 Sleep모드로 들어가서 기존의 MAC프로토콜보다 에너지가 효율적임을 수학적으로 증명하고 MATLAB으로 시뮬레이션 하였다.

• Journal of Acupuncture Research
• /
• 제21권2호
• /
• pp.1-20
• /
• 2004

Objective : The aim of this study was to investigate effects of Angelica gigas Nakai(AGN) on the ischemic injury by intraluminal filament insertion in the rats. Methods : The ischemia was induced by intraluminal filament insertion into middle cerebral artery. AGN herbal acupuncture into SP10 was carried out during 3 weeks after ischemic injury. Eight-arm radial maze was designed for the behavioral task. AGN herbal acupuncture showed neuroprotective agents in cresyl violet, acetylcholinesterase(AchE), choline acetyltransferase(ChAT) and nerve growth factor(NGF)-stain. Then check the effect of regional cerebral blood flow(rCBF) according to AGN herbal acupuncture in rats. Results : The errors in the eight-arm radial maze task were significantly decreased in normal group compared with control group on 1~6days, AGN2(0.02g/kg) herbal acupuncture group on 1~5days, AGN3(0.1g/kg) on 1~3days, AGN4(0.5g/kg) on 1, 3~6days. The rate of correct choice was significantly increased in AGN1(0.01g/kg) and AGN4 herbal acupuncture groups. The density of neurons in the hippocampal CA1 was the most increased in normal group and AGN1, AGN3, AGN4 herbal acupuncture groups compared with control group. The density of AchE in the hippocampal CA1 had a tendency to increase in all the groups when they were compared with control group, but not significant. The density of ChAT in the hippocampal CA1 was significantly increased in normal group and AGN1, AGN4 herbal acupuncture groups compared with control group. The density of NGF in the hippocampal CA1 was significantly increased AGN4 herbal acupuncture group compared with control group. The rCBF was significantly increased in AGN1, AGN3 and AGN4 herbal acupuncture groups without the change of blood pressure. Conclusions : These results suggest that AGN herbal acupuncture can be used for controlling stroke in early stage as herbal medication.

• 드라이브 ㆍ 컨트롤
• /
• 제11권2호
• /
• pp.30-35
• /
• 2014

The pumps of electro-hydrostatic actuators operate most frequently in boundary lubrication speed range, as they compensate for the position control errors as a control element. When conventional swash plate type piston pumps are applied to electro-hydrostatic actuators, the frictional power losses as well as the wear rate of sliding components, such as piston shoes can increase drastically under the boundary friction condition. In this paper, the power losses of the piston shoes were investigated which were engendered by a frictional solid-to-solid contact and leakage flow rate of their hydrostatic bearing. In order to reduce them, DLC-coating was applied to the swash plate and the ball joint of pistons along with its effects were demonstrated. In addition, it was also shown that the wear rate of the piston shoes could be markedly reduced using the DLC-coated swash plate.

• 한국정보통신학회논문지
• /
• 제25권11호
• /
• pp.1581-1587
• /
• 2021

임베디드 시스템의 활발한 사용으로 스마트 팩토리와 같이 여러 에지가 모여서 함께 복합적인 동작을 하게 되는 멀티 에지 시스템들이 동작되고 있다. 멀티 에지 시스템에서 하나의 에지에서의 이상 동작이 다른 에지로 전달되거나 전체 시스템이 다운되는 경우가 자주 발생한다. 이러한 시스템에서 각 에지의 이상 동작을 판단하고 제어하는 것이 중요하지만, 이는 성능의 한계가 존재하는 작은 에지의 임베디드 시스템에 부하를 가한다. 이러한 시스템에서 우리는 전력 소비 데이터를 사용하여 에지 장치의 상태를 확인하고 이를 QR코드 기반으로 데이터를 전송하여 서버에서 이상 동작을 확인하고 제어하려 한다. 논문에서 제안된 아키텍처는 에지의 전력 소모 데이터를 측정하기 위해 'chip-whisperer'를 사용하고 서버를 구현하기 위해 '라즈베리 파이'를 사용하여 구현하였다. 그 결과 제안된 아키텍처서버는 성공적인 데이터 전송 및 이상 동작 판정을 보였으며 에지에서 추가 부하가 나타나지 않음을 확인하였다.

• Nuclear Engineering and Technology
• /
• 제55권2호
• /
• pp.460-474
• /
• 2023

A simple but accurate mathematical model is crucial for dynamic simulations and controller design of helical coil once-through steam generator (OTSG). This paper presents a three-region movable boundary dynamic model of the helical coil OTSG. Based on the secondary side fluid conditions, the OTSG is divided into subcooled region (two control volumes), two-phase region (two control volumes) and superheated region (three control volumes) with movable boiling boundaries between each region. The nonlinear dynamic model is derived based on mass, energy and momentum conservation equations. And the linear model is obtained by using the transfer function and state space transformation, which is a 37-order model of five input and three output. Validations are made under full-power steady-state condition and four transient conditions. Results show good agreements among the nonlinear model, linear model and the RELAP5 model, with acceptable errors. This model can be applied to dynamic simulations and controller design of helical coil OTSG with constant primary-side flow rate.

• 한국기계가공학회지
• /
• 제14권2호
• /
• pp.67-74
• /
• 2015

In this study, analysis and experiments were carried out on temperature distributions and thermal deformations in a dry vacuum pump with vertical screws for safe operation. When a vacuum pump is working, it is necessary to get rid of the heat generated by the friction of bearings and the compression of air to prevent the vacuum pump from being damaged by interference between two screws and housing through thermal deformation. Additional cooling was proposed by using oil flow through the inner channel of the rotating axis for lower temperature control of the vacuum pump. Analysis and experimental results were compared in terms of temperature distribution and thermal deformation of the vacuum pump, and two sets of results matched reasonably well. These results for a dry vacuum pump with vertical screws can be used in similar model development and can minimize errors in design and manufacture by providing reasonably accurate prediction in advance.

• 대한기계학회논문집B
• /
• 제27권1호
• /
• pp.25-31
• /
• 2003

Airborne contaminant particles are intruded into optical disk drives(ODD) due to the flow caused by disk rotation and can be adhered to lens or disk surfaces, which causes decrease of laser power and increase of read/write errors. Such a phenomenon can be more serious as the space between the disk and the lens is reduced fur high-density storage devices. The purpose of this paper is to understand design parameters to reduce the particle intrusion into an ODD. Suggestions are made to prevent the particle intrusion that can decrease the stability of an ODD and also prevent the potential heat build-up problem. The sealing effect of drive and the forced injection of clean air (using HEPA filter) into the drive minimizes intrusion of the outside air and dusts in an ODD remarkably. Moreover it is proved by experiments that the installation of a heatproof pad to isolate heat generation part (PCB) from information read/write sections and the forced injection of dust-free air reduce the gas temperature inside the drive as well as the amount of particles intruded.