• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.135-138
• /
• 2011

한국형 달착륙선 개발을 위한 기초연구로 달착륙선 지상시험용 추진시스템의 개발을 진행 중이다. 착륙선의 하강을 위한 추력기는 200 N 급으로 설계유량 100 g/s, 연소실 압력 200 psi, 진공추력 220 N을 목표로 설계/제작 하였다. 연소시험을 위해 LM guide(Linear Motion Guide)를 이용한 추력시험장치를 꾸며 연소시험을 수행하였으며, 그 결과 연소실 압력 210 psi 일 때 유량은 96.1 g/s가 흘렀으며 그에 따른 추력은 약 160 N으로 측정되었다.

• 한국군사과학기술학회지
• /
• 제15권4호
• /
• pp.374-380
• /
• 2012

In guided missile systems, reducing terminal-position error is the primary objective of the inertial navigation system. As a seeker is used to sense and track a target, the critical function of the inertial navigation system is to provide the seeker with accurate missile attitude information and help the seeker to keep tracking a target continuously. As inertial sensor body and missile body alignment errors are taken into account, it is desirable to minimize the alignment errors between the missile seeker and the attitude of inertial navigation system. Among the alignment errors, this paper addresses the methods of measuring and compensating misalignment between inertial sensor body and housing frame and shows test results of several experiments.

• 보건행정학회지
• /
• 제16권2호
• /
• pp.49-76
• /
• 2006

The aim of this study was to explore the effects of a computerized review program which was introduced in August 1, 2003, using claims data for acute respiratory infection related diseases. National Health Insurance (NHI) claims data on respiratory infection related diseases before and after the introduction, with six month intervals respectively, were used for the analysis. Clinic was the unit of observation, and clinics with only one physician whose specialty was internal medicine, pediatrics, otorhinolaryngology and family medicine and clinics with a general practitioner were selected. The final sample had 7,637 clinics in total. Indices used to measure practice pattern was prescription rates of antibiotics, prescription rates of injection drug per visit, treatment costs per claim, and total costs per claim. Changes in the number of claims for major disease categories and upcoding index for disease categories were used to measure claiming behavior. Data were analysed using descriptive analysis, t-test for indices changes before and after the introduction, analysis of variance (ANOVA) for practice pattern change for major disease categories, and multiple regression analysis to identify whether new system influenced on provider' practice patterns or not. Prescription of antibiotics, prescription rates of injection drug, treatment costs per claim, and total costs per claim decreased significantly. Results from multiple regression analysis showed that a computerized review system had effects on all the indices measuring behavior. Introduction of the new system had the spillover effects on the provider's behavior in the related disease categories in addition to the effects in the target diseases, but the magnitude of the effects were bigger among the target diseases. Rates of claims for computerized review over total claims for respiratory diseases significantly decreased after the introduction of a computerized review system and rates of claims for non target diseases increased, which was also statistically significant. Distribution of the number of claims by disease categories after the introduction of a computerized review system changed so as to increase the costs per claims. Analysis of upcoding index showed index for 'other acute lower respiratory infection (J20-22)', which was included in the review target, decreased and 'otitis media (H65, H66)', which was not included in the review target, increase. Factors affecting provider's practice patterns should be taken into consideration when policies on claims review method and behavior changes. It is critical to include strategies to decrease the variations among providers.

• Nuclear Engineering and Technology
• /
• 제55권7호
• /
• pp.2642-2649
• /
• 2023

A real-time unmeasured dynamic response prediction process for the nuclear power plant pressure pipeline is proposed and its performance is tested in the test-loop system (KAERI). The aim of the process is to predict unmeasurable or unreachable dynamic responses such as acceleration, velocity, and displacement by using a limited amount of directly measured physical responses. It is achieved by combining a well-constructed finite element model and robust inverse force identification algorithm. The pressure pipeline system is described by using the displacement-pressure vibro-acoustic formulation to consider fully filled liquid effect inside the pipeline structure. A robust multiphysics modal projection technique is employed for the real-time sensor synchronized prediction. The inverse force identification method is also derived and employed by using Bathe's time integration method to identify the full-field responses of the target system from the modal domain computation. To validate the performance of the proposed process, an experimental test is extensively performed on the nuclear power plant pressure pipeline test-loop under operation conditions. The results show that the proposed identification process could well estimate the unmeasured acceleration in both frequency and time domain faster than 32,768 samples per sec.

• 정보과학회 컴퓨팅의 실제 논문지
• /
• 제21권4호
• /
• pp.308-314
• /
• 2015

사용성에 대한 사람들의 관심이 증가하고 있는 반면, 사용성 평가 계획의 수립과 진행, 평가결과의 수집과 분석을 지원하는 시스템은 미비한 실정이다. 사용성 평가는 크게, 사용성 평가 계획 수립, 실제 평가 진행, 평가 후 결과 수집 및 분석의 절차를 가지고 있으며, 본 논문에서는 사용성 평가의 전 과정에서 활용할 수 있는 웹 기반 사용성 평가 시스템을 설계 및 구현하였다. 따라서, 사용성 평가에 참가하는 참가자들은 언제 어디서나 기기에 상관없이 효과적으로 사용성 평가에 참여하고, 사용성 평가 책임자는 평가 관련 문서와 결과 데이터를 보다 효율적으로 관리하고 평가의 전 과정의 진행에서 신뢰도를 높일 수 있는 시스템을 구현하는 데 목표를 두었다. 웹 기반 사용성 평가 시스템은 제품의 사용성 평가를 실제 사용하는 장소에서 바로 수행할 수 있다는 장점과 이동이 불편한 장애인 대상 제품의 사용성 평가에 유용할 것으로 기대한다.

• Nuclear Engineering and Technology
• /
• 제50권4호
• /
• pp.570-581
• /
• 2018

Recently, a software program has been used in nuclear power plants (NPPs) to digitalize many instrumentation and control systems. To guarantee NPP safety, the reliability of the software used in safetycritical instrumentation and control systems must be quantified and verified with proper test cases and test environment. In this study, a software testing method using a simulation-based software test bed is proposed. The test bed is developed by emulating the microprocessor architecture of the programmable logic controller used in NPP safety-critical applications and capturing its behavior at each machine instruction. The effectiveness of the proposed method is demonstrated via a case study. To represent the possible states of software input and the internal variables that contribute to generating a dedicated safety signal, the software test cases are developed in consideration of the digital characteristics of the target system and the plant dynamics. The method provides a practical way to conduct exhaustive software testing, which can prove the software to be error free and minimize the uncertainty in software reliability quantification. Compared with existing testing methods, it can effectively reduce the software testing effort by emulating the programmable logic controller behavior at the machine level.

• 한국소음진동공학회논문집
• /
• 제16권7호
• /
• pp.704-711
• /
• 2006

Vibration test on MAST(multi axial simulation table) system has several advantage over one-axial vibration test that could simulate 6-DOF, 3-axial translation and 3-axial moment, at the same time. Since field vibration motion can be fully represented with 6-DOF, multi-axial vibration test on vehicle component is widely conducted in technical leading companies to make sure its fatigue performance in vibration environment. On the way to fulfill the process, editing technique of obtained field data is key issue to success a reliable vibration testing with MAST system. Since the original signals are not only too large to fulfill it directly, but all of the measured data is not guarantee its convergency on generating its driving files, editing technique of the original signals are highly required to make some events that should meet the equal fatigue damage on the target component In this paper, key technique on editing a field data feasible for MAST system is described based on energy method in vibration fatigue. To explain its technique explicitly, author first introduced a process on field data acquisition of two vehicle component and then, representing events are produced to keep up with the editing strategy about a energy method. In the final chapter, a time information regarding a vibration test on MAST system is derived from the energy data which is critical information to perform a vibration test.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.109-114
• /
• 2008

This paper presents the development status of a subscale precooled turbojet engine "S-engine" for the hypersonic cruiser and space place. S-engine employs the precooled-cycle using liquid hydrogen as fuel and coolant. It has $23cm{\times}23cm$ of rectangular cross section, 2.6 m of the overall length and about 100 kg of the target weight employing composite materials for a variable-geometry rectangular air-intake and nozzle. The design thrust and specific impulse at sea-level-static(SLS) are 1.2 kN and 2,000 sec respectively. After the system design and component tests, a prototype engine made of metal was manufactured and provided for the system firing test using gaseous hydrogen in March 2007. The core engine performance could be verified in this test. The second firing test using liquid hydrogen was conducted in October 2007. The engine, fuel supplying system and control system for the next flight test were used in this test. We verified the engine start-up sequence, compressor-turbine matching and performance of system and components. A flight test of S-engine is to be conducted by the Balloon-based Operation Vehicle(BOV) at Taiki town in Hokkaido in October 2008. The vehicle is about 5 m in length, 0.55 m in diameter and 500 kg in weight. The vehicle is dropped from an altitude of 40 km by a high-altitude observation balloon. After 40 second free-fall, the vehicle pulls up and S-engine operates for 60 seconds up to Mach 2. High altitude tests of the engine components corresponding to the BOV flight condition are also conducted.

• 한국전자파학회논문지
• /
• 제23권8호
• /
• pp.1002-1009
• /
• 2012

본 연구는 미시간 주립대(Michigan State University)의 바이스태틱 레이다 시스템을 통하여 수집한 측정 데이터를 이용한 표적 구분에 관한 연구 결과이다. 본 연구에서는 먼저 F-14, Mig-29, F-22 스케일 모델에 대하여 $30^{\circ}$, $60^{\circ}$, $90^{\circ}$ 바이스태틱 각도에서의 측정을 수행하였다. 측정한 데이터로부터 시간-주파수 영역 해석법인 단시간 퓨리에 변환(Short Time Fourier Transform)과 연속 웨이브릿 변환(Continous Wavelet Transform)을 이용하여 특성 벡터를 추출하고, 신경망 구분기를 통하여 표적 구분 실험을 수행하였다. 실험 결과, 바이스태틱 각도에 따라 표적 구분 성능에 많은 변화가 있으며, 특히, $60^{\circ}$ 바이스태틱 각도에서 가장 좋은 구분 성능을 가짐을 알 수 있었다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
• /
• pp.349-352
• /
• 2005

The telematics positioning testbed is an infrastructure to test and verify positioning technology, the sub-component of telernatics system. The positioning testbed provides the environment of performance analysis for acquisition of static and dynamic positioning information using telematics vehicle. This testbed consists of onboard positioning system, positioning reference station and lab positioning server. The onboard positioning system equipped in telematics vehicle, consists of target positioning system, reference positioning system, and analysis tool. A equipment acquiring high precision positioning data obtained from GPS combined with IMU was set as a reference positioning system. Analysis tool compares observed positioning data with high precision positioning information from a reference positioning system, and processes positioning information. Positioning reference station is RTK system used for reducing atmosphere error, and it transmits corrected information to reference positioning system. Positioning server which is located at laboratory manages positioning database and provides monitoring data to integrated testbed operating system. It is expected that the testbed supports commercialization of telernatics technology and services, integrated testing among component technology and verification.