• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.2
• /
• pp.10-18
• /
• 2010

Scramjet engine is one of the core parts of hypersonic vehicle of next generation and being investigated by many countries. Korea Aerospace Research Institute performed a ground test of the model scramjet engine S1 in 2007. And, S2 model which is improved from S1 model in engine startability and thrust was tested with HIEST (High Enthalpy Shock Tunnel) at Kakuda Space Center of JAXA. Design condition of S2 model was Mach 6.7, however, it was tested at Mach 7.7 as an off-design condition test. As a test result, flow separation was found at the inside of the intake, but the engine showed stable combustion pressure distribution. Furthermore, compared to other test models, S2 model showed a good performance value in thrust and specific impulse.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.6 no.4
• /
• pp.342-348
• /
• 2018

The present study examined the various strength and deformation performances of molding materials recycled using film packaging wastes to ascertain the their applicability to secondary products in construction industries. The stress-strain relationships of molding materials were measured under compression, tension, and flexure in accordance with the ASTM procedure. The measured mechanical properties of recycled molding materials were comparable to typical ranges observed in low-density polyethylene and/or high-density polyethylene. However, to stabilize the properties of the molding materials, further management systems are required as follows: 1) evaluation of mechanical properties of materials with respect to various mixing proportions of waste ingredients; 2) estimation of the effect of foreign substance and moisture contents on the mechanical properties; and 3) establishment of comprehensive database including various sources such as manufacture process including applied pressure to produce the molding materials, and collection region and time of wastes.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.4
• /
• pp.334-341
• /
• 2015

This paper develops a new system for remotely monitoring and controlling the windows and doors in mobile environment. We design and implement the opening and shutting unit, the gateway, and the control server system, respectively. The opening and shutting unit consists of the driver using DC motor and the motion controller which monitors the state and transfers the control information. The gateway supports TCP/IP and CDMA protocol, which is the interface of wire and wireless communication for transferring the current state and control information. The control server consists of the program to store and process the control information, the middleware to support the processing of various state message, and DB for monitoring the state and remotely controlling the system. Especially, an application software and the Web-based user interface have also been developed to support the mobile environment. The operation performances, environment influences, driving persistences, and operation failure ratio, which are based on PC and smart-phone, have been tested in 2 authorized agencies. The test results show that the developed system has a superior performance.

• Journal of Satellite, Information and Communications
• /
• v.11 no.4
• /
• pp.107-113
• /
• 2016

In this paper, we suggest a design method of a wide-band Butler matrix working at 5.9 GHz for V2X communication antennas. Since V2X communication needs beam-forming and beam-steering antennas to make transportation systems, mobile comm platforms, saturated frequency-resources, and signal TX-and-RX smart, multi-functional, resolved, and efficient utmost, respectively, the proper Butler matrix and its radiating elements as a low-profile geometry are realized. The constitutive components of the basic Butler matrix of a narrow band are designed first. And then, it is extended to a wide-band version to make its frequency-shift less affected by the event of the antenna system being mounted on a car body. The beam-forming and beam-steering performance is presented as the common feature tagged along with the different bandwidths of the frequency responses as the comparison between the narrow- and wide-band cases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.1
• /
• pp.47-55
• /
• 2012

This paper describes the developed HILS and test equipment in order to test the performances of MMW(Millimeter-Wave) seeker which can detect and track a high speed of short-range ballistic missile and aircraft. This system is used to 141 horn antenna array, array switching, and gain and phase control algorithm to simulate various kind of targets and trajectory of high speed and maneuver moving target. In addition, it simulates not only velocity and range for these targets but also clutter and jamming environments. System configuration and implementation and the measurement results of major subsystems such as target motion simulator, simulation signal generator, high speed data aquisition unit, and central control unit are presented. These systems could verify the detection and tracking performance of MMW seeker through dynamic real-time test based on simulation flight scenario.

• Korean Chemical Engineering Research
• /
• v.46 no.5
• /
• pp.915-921
• /
• 2008

In most PEM fuel cell research, effects of cell geometry, physical properties of component such as membrane, carbon cloth, catalyst, etc. and water transport phenomena are key issues. The scope of these research was limited to single cell and stack except BOP(Balance of plant) of fuel cell. The research fouced on the fuel cell system usually neglect to consider detailed transport phenomena in the cell. The research of the fuel cell system was interested in a system performance and system dynamics. In this paper, the effect of the anode recirculation is calculated using the 2D steady-state model. For this work, 2D steady-state modeling and experiments are performed. For convenience of modifying of model equation, not commercial pakage but the in-house algorithm was used in simulation. For an vehicle industry, the analysis of the anode recirculation system helps the optimization of operating condition of the fuel cell.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.2
• /
• pp.143-152
• /
• 2019

In this paper, we described the design of Ka-band planar active phased array antenna which is applicable for small RADAR for airborne and seeker of guided missile. The antenna consists of about 1000 array radiating elements and is designed to be within 200mm diameter. We optimized the spacing of radiating elements to allow beem steering above ${\pm}55$ degrees of Field of view, and analyzed the performance of antenna. We confirmed that the Effective Isotropic Radiated Power (EIRP) of the antenna can be 94.22 dBm and receive G/T can be 1.68 dB/k through the designs of RF components and the verification of RF budget. The TX output of TR Module is designed to be over 1.3W for EIRP, and Receive noise figure of TR Module is designed to be less than 5dB for G/T.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1045-1059
• /
• 2011

A 3-D multi-function radar(MFR) is a modern radar to provide various target information, such as range, doppler, and angle by performing surveillance, multiple target tracking, and missile guidance. In this paper, we introduced a real-time radar signal processor(RSP), which is a crucial component of MFR with its design, implementation using high-speed multiple DSP, and performance. Additionally, we verified that several advanced signal processing algorithms were well-performed in our RSP, such as MCA-CFAR algorithm for target detection in clutter environment, range and velocity measurement algorithm using discriminator estimation, and noise jammer detection algorithm using local minimum selection.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.05a
• /
• pp.11-17
• /
• 2009

Hot-fire test of a turbopump for a gas generator cycle rocket engine of 30 ton class was carried out in real propellant environment. Liquid oxygen and kerosene were used for the oxidizer pump and the fuel pump, respectively, while hot gas produced by the gas generator was supplied to the turbine. A part of the propellant discharged from the pumps was provided to the gas generator. The turbopump was run stably at both on-design and off-design conditions, satisfying all the performance requirements. This paper describes one of the test cases, where the turbopump was run for 120 seconds at three different operating modes in one test. In terms of performance characteristics of pumps and turbine, the results from turbopump assembly test using real propellant showed a good agreement with those from the turbopump component tests using simulant working fluid.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.8
• /
• pp.791-796
• /
• 2012

Small gas turbine engines are used in aircraft as an auxiliary power unit (APU) to supply compressed air to start the main engine and for emergency electricity. When an aircraft is operating in an environment in which sand and dust is present in the ambient air, the engines as well as the APU ingest the sand and dust. This causes erosion of the engine and a degradation in its performance. The present study investigated the effect of sand and dust ingestion on small gas turbine engines. The concentration of sand and dust was $4.4{\times}10^{-5}kg$ per unit kg of air, which follows the specification in MIL-E-8593. The test was conducted for 10 h, and the engine performance before and after the test was compared. In addition, a tear-down inspection was conducted to examine the erosion patterns of sub-components such as the impeller and turbine wheel.