• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.521-526
• /
• 2004

This paper introduces works performed for reducing high frequency noise of a reciprocating compressor. Noise in a high frequency range strongly affects sound quality as well as increases total noise level of the compressor. In order to reduce the noise, two different works were carried out. the first work was to measure the vibration Power transferred through suspension spring and discharge pipe; and the second one was to obtain operational deflection shape from cross-power spectrum measured on shell. Based on the information, Adequate structural modification of the transfer path and shell resulted in noise reduction in a high frequency range.

• Journal of Aerospace System Engineering
• /
• v.16 no.1
• /
• pp.70-80
• /
• 2022

An aerial refueling provides for extension of operational time and range for aircraft and enhances mission effectiveness, hence it application by most military aircrafts. The receiver aircraft should have the aerial refueling clearance that is established by performing technical and operational compatibility assessments to certify it for aerial refueling with a specific tanker model. The compatibility assessment includes aerial refueling handling qualities, functional, fuel, lighting system testing and it is finally verified through flight testing. However, since aerial refueling compatibility assessments have never been performed in Korea, there is no experience to determine the test requirements and the scope and size of the test program for a new development aircraft. This paper therefore introduces the common techniques of aerial refueling and aerial refueling flight test methods to understand the aerial refueling FCS (Flight Control System), OFP (operational flight program) and system validation, and aerial refueling envelope clearance of a fixed wing aircraft for a boom and receptacle refueling system that is being introduced into Korea Air Force.

• Journal of Advanced Marine Engineering and Technology
• /
• v.11 no.4
• /
• pp.59-74
• /
• 1987

In this dissertation, a complete model of commutatorless static Kramer type slip power recovery system of 3.phi. induction motor has been designed and tested in the laboratory, and the experimental results are compared with the numerical values. The main results of this study are summerized as follows. (1) Maintenance and repair of the mechanical commutator is obviated by adopting a thyristor commutator in place of the mechanical commutator in the conventional Kramer system. (2) The experimental results of developed torque, and stator current are generally coincided with the numerical values obtained by the derived equation, proving their validity. (3) This system is simulated and the following operational characteristics are obtained with suitable design values : (a) The speed control range of 7:1 is obtained when the turn ratio of induction motor is lowered to about 3:1 to 4:1 and the generating constant of auxiliary synchronous motor is increased to 120-175 range. (b) Its efficiency can be increased to 75-85%, the range for static Scherbius system and its power factor takes values in the range of 65-85%, which is twice of the range for static Scherbius system.

• Atmosphere
• /
• v.21 no.2
• /
• pp.197-208
• /
• 2011

The objective of this study is to describe the short-range forecast system of the Korea Air Force (KAF) and to verificate its performace in 2009 summer. The KAF weather prediction model system, based on the Weather Research and Forecasting (WRF) model (i.e., the KAF-WRF), is configured with a parent domain overs East Asia and two nested domains with the finest horizontal grid size of 2 km. Each domain covers the Korean peninsula and South Korea, respectively. The model is integrated for 84 hour 4 times a day with the initial and boundary conditions from National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) data. A quantitative verification system is constructed for the East Asia and Korean peninsula domains. Verification variables for the East Asia domain are 500 hPa temperature, wind and geopotential height fields, and the skill score is calculated using the difference between the analysis data from the NCEP GFS model and the forecast data of the KAF-WRF model results. Accuracy of precipitation for the Korean penisula domain is examined using the contingency table that is made of the KAF-WRF model results and the KMA (Korea Meteorological Administraion) AWS (Automatic Weather Station) data. Using the verification system, the operational model and parallel model with updated version of the WRF model and improved physics process are quantitatively evaluated for the 2009 summer. Over the East Aisa region, the parallel experimental model shows the better performance than the operation model. Errors of the experimental model in 500 hPa geopotential height near the Tibetan plateau are smaller than errors in the operational model. Over the Korean peninsula, verification of precipitation prediction skills shows that the performance of the operational model is better than that of the experimental one in simulating light precipitation. However, performance of experimental one is generally better than that of operational one, in prediction.

• Journal of the Korean Society of Food Culture
• /
• v.22 no.5
• /
• pp.621-632
• /
• 2007

The purposes of this study were as follows. First is to compare the importance of operational factors to determine types of school breakfast program, and second is to do the preference analysis of operation-related people depending on the attributes and levels of the operation of school breakfast program. The questionnaires developed for this study were distributed to 134 school dietitians, 114 school foodservice officials at the educational board, 68 staff members of foodservice contractors and 493 parents. Statistical data analyses were performed using SPSS/WIN 12.0 for descriptive statistics and conjoint analysis. The conjoint design was applied to evaluate the hypothetical foodservice types. According to the analysis on the attributes and levels of the school breakfast operation, the relative importance of each attribute was as followsprice (36.30%), menu (29.60%), foodservice staff (22.54%), serving type (11.55%) to school dietitians, price (34.99%), menu (28.15%), foodservice staff (23.52%), serving type (13.35%) to school foodservice officials at the educational board, menu (30.55%), price (30.24%), foodservice staff (28.75%), serving type (10.47%) to staff members of foodservice contractors and price (36.34%), menu (29.73%), foodservice staff (21.01%), serving type (12.92%) to parents. The results of the conjoint analysis indicated that the school dietitians and school foodservice officials at the educational board preferred the school breakfast operation program with 3 traditional menus and 2 convenience menus per 5 day, $1{\sim}3$ foodservice staff, with a price range of $1501{\sim}2000won$, and tray serving. Staff members of foodservice contractors preferred the school breakfast operation program with 3 traditional menus and 2 convenience menus per 5 day, $1{\sim}3$ foodservice staff, with a price range of $2501{\sim}3000won$, and tray serving. Parents preferred the school breakfast operation with 5 traditional menus per 5 day, $6{\sim}7$ foodservice staff, with a price range of $2501{\sim}3000won$, and tray serving. About a half of school dietitians considered that elementary schools were appropriate for the suggested school breakfast operation program. But, 68.2% of school foodservice officials at the educational board, 69.1% of staff members of foodservice contractors, and 38.1% of parents considered high schools to be the suitable model. Therefore, it indicated the need to recognize the different opinions among breakfast operation-related people and take these factors into consideration in developing the school breakfast program.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.4
• /
• pp.363-373
• /
• 2019

Waste characterisation associated with nuclear site decommissioning relies on radiochemical analysis of a diverse range of sample types, requiring extensive validation of analytical techniques using matrix-matched materials. The absence of relevant reference materials has hindered robust method development and validation. The paper discusses how method validation in support of nuclear waste characterisation can be achieved without using reference materials. The key stages in an analytical procedure are evaluated and a multi-stage approach is proposed with the ultimate aim of determining an operational envelope for an analytical procedure.

• ETRI Journal
• /
• v.29 no.6
• /
• pp.811-813
• /
• 2007

We report on a ridge waveguide laser diode with laterally tapered waveguides fabricated in a single growing step using a double patterning method. In this structure, nearly constant output power is obtained with the change of the lower tapered waveguide width, and the facet power ratio of 1.4 to 1.5 is observed over the current range. The asymmetric facet power property is also investigated.

• Proceedings of the IEEK Conference
• /
• 2002.06e
• /
• pp.87-90
• /
• 2002

This paper describes design technique of switched-capacitor 1V delta-sigma modulator. To solve the incomplete switching operation at low voltage, bootstrapping technique is used. For PMOS input pair of 1V operational amplifier, simple common mode level down technique is used. Designed 2nd order single loop modulator has an oversampling ratio of 64 and obtains a peak SNR of 71dB, a dynamic range of 73 dB with the power consumption of 350uW at 1V power supply.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.147-149
• /
• 2007

A new half bridge converter without DC offset of magnetizing current is proposed. The proposed half bridge converter can realize no DC offset of magnetizing current as well as no circulating current, and guarantee ZVS operation. Therefore it has high efficiency and high power density, especially in wide input range. The operational principle, DC conversion ratio and ZVS analysis are presented. Experimental results demonstrate that the proposed converter can achieve a significant improvement in the efficiency.

• Journal of the Korea Society for Simulation
• /
• v.29 no.3
• /
• pp.57-72
• /
• 2020

To respond to the threat of Long range artillery of North Korea, it is necessary to establish the Korean counter long range artillery intercept system(CLRAIS). The purpose of this study is to study the operational concept of the CLRAIS against the threat of long range artillery of North Korea, and to develop the operational effectiveness process of the CLRAIS. First, we set up the operating concept of the CLRAIS and established the concept of an effectiveness in a many-to-many engagement situation and a process to derive it. Based on this, a tool was developed to analyze the actual effectiveness. In order to find out the factors influencing the effectiveness in many-to-many engagement situations, simulation experiments were performed by combining various variables such as detection assets, engagement control, and launchpad performance. As a result, it was found that in addition to the missile performance, the performance of the detection assets and the engagement control center had a significant impact on the intercept rate and the defense success rate. These findings can be used to understand important indicators in terms of effectiveness in many-to-many engagement situations in the future development of weapon system, and to determine the development direction and target value of each element necessary for the level of defense success rate to be achieved.