• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2606-2611
• /
• 2008

The high energy fluid leakage from the high temperature and high differential pressure drop system of NPPs (Nuclear Power Plants) decreases efficiency and consequently leads to considerable economic loss due to less power production. Also, the leakage possibly damages critical parts of components such as valve and trim with the effect of cavitation, flashing, and erosion, etc. and deteriorates its performance. Thus, in this study, we diagnosed the as-is leakage for four (4) main steam drain valves and two (2) steam traps of Yonggwang 1,2 units during normal operation by using multi-measuring technique and observed the occurrence of fine leakage. In the course of measuring fluid leakage, the sign of fine leakage is estimated to be the leakage from orifice. By converting the leakage to energy loss, it is equivalent to the amount of several hundred thousand won per each unit, which supports the basis for the justification of fine leakage.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2016.01a
• /
• pp.125-128
• /
• 2016

본 논문에서는 다중 생체계측 장비를 CMCIS(Central Monitoring and Cardiology Information System) 기반의 통합 시스템에 연동하기 위한 MDEC(Medical Device Exchange Communication)의 설계 및 구현을 소개한다. MDEC은 6종의 계층장비의 신호를 받아 각 서버로 데이터를 전송할 수 있도록 설계하고 Linux OS을 포팅 하였다. 각 장비별 프로토콜에 대해 최소화된 기본 프로토콜을 정의하고 통신방법에 따라 UART 포트 혹은 USB 포트를 생체정보의 물리적 입력장치로 사용하였다. 호스트 서버와는 유무선 LAN울 통해 정보를 전달할 수 있게 하드웨어를 설계하였다. 본 연구의 결과는 CMCIS 기반의 통합 시스템을 구축하는 기반기술로 향후 효율적 의료서비스에 기여할 것으로 사료된다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.1016-1020
• /
• 2017

This study was conducted to develop a test facility that simulates the combustion instability that occurs in a real-scale liquid rocket combustor. A separate engine head with 3 injectors arranged in a row was designed/manufactured and verified through preliminary tests. The flow rate and spray pattern of the head were confirmed by the cold flow test. Next, propellant spray test and combustion test were carried out. A preliminary combustion test was carried out at 10 bar and the combustion chamber pressure was measured to be significantly lower than the target pressure. This is because it was a low pressure test, and it is expected to be resolved in the high pressure test in the future.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.49 no.2
• /
• pp.62-67
• /
• 2000

The uniformity of temperature on a wafer is one of the most important parameters to control the RTP (Rapid Thermal Process) with proper input signals. Since it is impossible to achieve the uniformity of temperature without exact estimation of temperature at all points on the wafer, the difficulty of understanding internal dynamics and structural complexities of the RTP is a primary obstacle to accurately measure the distributed temperatures on the wafer. Furthermore, it is also hard to accomplish desirable estimation because only few pyrometers have been commonly available in the general equipments. In the paper, a thermal model based on the chamber geometry of the AST SHS200 RTP system is developed to effectively control the thermal uniformity on the wafer. First of all, the estimation method of one-point measurement is developed, which is properly extended to the case of multi-point measurements. This thermal model is validated through certain simulation and experiments. The work can be usefully contributed to building a run-by-run or a real-time controls of the RTP.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.111-113
• /
• 2007

본 논문에서는 FPGA를 사용하여 진행파형 초음파 모 터의 2상 입력 전원 전압의 주파수, 위상차, 진폭 및 2 상간의 전압차 조절이 가능하고, 8대의 초음파 모터를 동 시에 제어할 수 있는 8채널 USB통신 PC기반 초음파 모터 디지털 제어기를 제안한다. 제안한 제어기는 FPGA를 이용 한 디지털 논리에 의해 출력을 발생하기 때문에 PC로부 터 직접 제어 명령을 입력 받아 각각의 파라미터를 실시 간으로 조절할 수 있을 뿐만 아니라, 둘 이상의 파라미터 를 동시에 조절이 가능하다. 또한, PC와의 인터페이스는 USB통신 방식을 채택하여 제어 명령의 전달속도 향상 및 플러그 앤 플러그 방식을 통해 데스크 탑 컴퓨터는 물론 휴대용 컴퓨터나 PDA와 같은 다양한 플랫폼에서 사용할 수 있도록 설계하였다. 또한, 초음파 모터의 속도 및 위치를 계측하기 위해 사용된 로터리 엔코더 카운터 회로를 FPGA회로에 내장시켜 카운터를 위한 별도의 회로 구성이나 장비 구입의 필요성을 배제하였다. 따라서, 생산 단가 및 부피를 현저히 감소시켰다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.24-27
• /
• 2012

In this study, the full scale flight type Dual-Pulse Rocket Motor(DPRM) with the bulkhead type Pulse Separation Device(PSD) was designed, manufactured, and fire-tested. The bursting time and pressure of PSD were analyzed by the pressure, thrust and vibration results of static fire tests and ablation of PSD was measured with 3-D coordinate measuring machine. As a result, PSD requirements, bursting conditions and thermal safety, were satisfied.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.4
• /
• pp.19-30
• /
• 2000

A finite-volume method is developed to solve turbulent flows around modern commercial hull forms with bow and stern bulbs. The RANS equations are solved. The cell-centered finite-volume method employs QUICK and central difference scheme for convective and diffusive flux discretization, respectively. The SIMPLEC method is adopted for the velocity-pressure coupling. The developed numerical methods are applied to calculate turbulent flow around KRISO 3600TEU container ship. Surface meshes are generated into five blocks: bow and stern bulbs, overhang, fore and afterbody. 3-D field grid system with O-H topology is generated using elliptic grid generation method. Surface friction lines and wake distribution at propeller plane is compared with experiment. The calculated results show that the present method can be used to predict flow around a modern commercial hull forms with bulbs.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.110-110
• /
• 2021

사회적, 환경적으로 크고 작은 문제를 일으키는 녹조현상은 수생태계에서 1차 생산자로 없어서는 안 될 조류의 과대 성장으로 인해 주로 나타난다. 담수조류는 크게 녹조류, 남조류, 규조류 3종으로 나누어지며, 특히 남조류는 계절별 천이에 따른 발생 시 과대 성장하는 특성으로 인해 녹조현상에 가장 큰 원인이 된다. 이러한 녹조현상의 원인에 따라 환경부에서는 발령기준 항목을 chl-a와 남조류 세포수에서 2016년 이후 남조류 세포수 만으로 발령기준 항목을 개정하였다. 따라서, 녹조현상에 대한 신속한 대처를 위해서는 남조류에 대한 분포에 대해 파악하는 것이 가장 우선시 되며 이를 위해 신속한 모니터링을 필요로 한다. 하지만 현재 조류 모니터링을 위해서는 직접 채수를 통한 검경 또는 Lisst, YSI와 같은 직접 계측 센서를 활용하여 모니터링을 진행을 하고 있으며 이러한 점, 선 단위의 측정은 전반적인 조류 분포 및 현황에 대하여 파악과 신속한 모니터링에 한계가 있다. 이러한 한계에 대안으로 위성영상, 다중분광 및 초분광 영상을 활용한 면단 위의 원격 모니터링을 통해 신속하고 하천 내 전반적인 조류 농도 분석을 위한 연구가 다양하게 진행되고 있다. 본 연구에서는 UAV를 활용한 초분광센서를 이용하여 하천과 일정한 반사율을 가지는 반사천을 촬영하고 취득한 초분광영상 보정 및 분석을 진행하였다. 최적 밴드 비를 산정하고 YSI를 통한 Chl-a 결과를 이용하여 분광 특성별 맵핑을 통한 공간적 분포의 조류 농도를 산정하고자 한다.

• The korean journal of orthodontics
• /
• v.26 no.4
• /
• pp.414-420
• /
• 1996

Cephalometric measureements have disadvantage of representing cranio-facial structures in two dimension only and therefore they pose limitations in describing three-dimentional structures of cranio-facial region. More interests have been put on the correlation between the two planes. This study evaluated correlations between facial type score, which allows effects on malocclusion, growth change prediction and establishment of treatment method and prognosis, and measurements from submentovertex view. Cephalometric view and submentovertex view were taken of skeletal Class I adults with optimal profile and correlations between them have been observed. Following results were obtained: 1. To learn about factors that influence average condylar angulation, FACE, INT-CO-ANG, MN-CORPUS, CON-RATIO, GON-RATIO, MN-RATIO were used as variables and underwent multiple regression analysis. As a result, the following equation was obtained : CON-AVE=.l73(FACE)-.322(INT-CO-ANG)+36.34(GON-RATIO) +.420(MN-CORPUS) (($R^2=.85451$) 2. The following equation was obtained concerning facial type score. FACE= .050(CON-ANG)+.023(INT-CO-ANG)-.075(MN-CORPUS)($R^2=.31547$) 3. Among the submentovertex measurements, MN-CORPUS, CON-RATIO, GON-RATIO, MN-RATIO showed close correlations. (P<0.05) 4. Average condylar angualtions were $23.37^{\circ}$ on the right and $20.71^{\circ}$ on left. There was a difference between the two. FACE : facial type soore. CON-ANG: mean value of condylar angulation. CON-AVE: mean value of Rt. Lt condylar angulation. INT-CO-ANG : angle between Rt. Lt condylar axis. MN-CORPUS : angle formed between RT. Lt gonion & pogonion. CON-RATIO: lntercondylar distance/mandibular body length. GON-RATIO : intergonion distanoe/mandibular body length. MN-RATIO: lntermylohyoid distance/mandibular body length. MX-RATIO: intermaxillary tuberosity distance/ANS-PNS distance.

• Journal of Korea Water Resources Association
• /
• v.51 no.2
• /
• pp.151-163
• /
• 2018

The objective of this study was to estimate LOADEST (LOAD Estimator) coefficients for simulating pollutant loads in ungauged watersheds. Regression models of LOADEST were used to simulate pollutant loads, and the multiple linear regression (MLR) was used for coefficients estimation on watershed characteristics. The fifth and third model of LOADEST were selected to simulate T-N (Total-Nitrogen) and T-P (Total-Phosphorous) loads, respectively. The results and statistics indicated that regression models based on LOADEST simulated pollutant loads reasonably and model coefficients were reliable. However, the results also indicated that LOADEST underestimated pollutant loads and had a bias. For this reason, simulated loads were corrected the bias by a quantile mapping method in this study. Corrected loads indicated that the bias correction was effective. Using multiple regression analysis, a coefficient estimation methods according to the watershed characteristic were developed. Coefficients which calculated by MLR were used in models. The simulated result and statistics indicated that MLR estimated the model coefficients reasonably. Regression models developed in this study would help simulate pollutant loads for ungauged watersheds and be a screen model for policy decision.