• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.225-232
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• 2019

The satellite-based ionospheric model consists of local first-order plane function parameters for individual satellites and provides excellent accuracy in the flat ionospheric environment of the Korean Peninsula. This paper analyzes the performance of such model under the rapid changes in the ionosphere. Rapid changes in the ionosphere were observed in Korea from September to October 2014, and a satellite-based ionosphere model was applied to Wide Area Differential GPS (WADGPS) to analyze the navigation performance and the performance of estimating ionospheric delay errors. After processing the test data, it was confirmed that there was a deterioration in navigation performance and extrapolation performance in low-latitude areas and analyzed the cause.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.454-455
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• 2018

The impedance of an underwater acoustic transducers constituting a multi-channel array structure could be changed in real time by various transmission modes. A power amplifier for driving the transducers usually use a voltage control method, so the transducer and power amplifier may be damaged by over-power due to changeable load conditions. Therefore, the drive controller of the power amplifier should have the function of limiting the power. This paper propose the new voltage control method for limiting the driving power of transducers with variable impedance characteristics.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.6
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• pp.480-485
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• 2013

This paper include the results of the software interface design for the ground vehicle simulators. This design allows us to upgrade the simulator easily by exchanging the engineering model when we need to change the function of algorithm or data of a simulator. That is because a main part of simulator is composed of reusable model.

• Journal of Distribution Science
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• v.4 no.2
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• pp.123-144
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• 2006

For the property right's protection of the nation, the uncertainty's dissolution and the reliability's security of real estate trade are very important. With the life style's change, the market of real estate becomes diversification, and the level of the real estate trade becomes diversification. But compared with this, the trade system of the real estate has not broken away from the mode in the past yet. To cope with it actively, it needs to review the real estate trade form. Especially, it needs to investigate a plan that can advance the Agency Listing method. The Exclusive Agency Listing and the real estate Information Network System have been the usual system in some advanced countries like America, Japan. It is the system that establishes the real estate brokerage's trade order and encourages the execution for the real estate client's property right's protection and benefit offer. In our country, The Exclusive Agency Listing and the real estate Information Network System were created in the revised real estate brokerage law in 12, 1993. But because of varies of questions, it can not be settled down. So this paper will develop the characteristic factors of the Exclusive Agency Listing and the real estate Information Network System revitalization and examine the mutual relation depends on the factors. And these factors were studied through the proved analysis to the effecting made on the Agency function's consideration and real estate broker' trust and customer satisfaction. So depends on these, the existed value now will present the revitalization plan and political implication about the Exclusive Agency Listing and the real estate Information Network System.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.3
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• pp.172-180
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• 1997

The microstructure, tensile and impact properties of forgings of 7175 aluminium alloy have been studied as a function of intermediate thermo-mechanical treatment(ITMT) process. The ITMT process is consisted of warm working and recrystallization. In the case that the billet was warm-worked above 60% below $250^{\circ}C$ and recrystallized at $475^{\circ}C$, the grain size revealed about $17{\mu}m$ which corresponds to one third of that of conventional process. The refinement of grain size leaded to the improved ductility and impact energy without sacrifice of tensile strength. It was found that the ITMT processed specimen behaved isotropically due to the near equiaxed grains. It was observed that the ITMT processed specimen showed the mixed fracture mode of transgranular and intergranular, instead of intergranular mode. This change of fracture mode contributed to the improved ductility and impact property.

• Digital Contents
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• no.5 s.108
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• pp.90-95
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• 2002

지난 호에서는 정적 SQL(Static SQL)의 장점과 Oracle8i에서 도입된 analytic function이라는 새로운 기능을 이용해서 부분범위처리가 가능한 효율적인 게시판 구현에 대해서 살펴보았다. 이번 호에서는 analytic function, FBI(Function Based Index), 순환관계(connect by ㆍㆍㆍstart with)를 이용한 응답글(속칭 리플)이 있는 게시판의 부분범위처리에 대해서 살펴보고, 게시판의 총글수나 사용자별 마일리지합 정보 등 집계성이나 항상 사용자가 온라인상에 보고자하는 정보들을 효율적으로 관리하기 위해 materialized view를 적용하는 방법에 대해서 알아보겠다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.305-325
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• 2015

In this paper, missile homing guidance laws to control the impact angle and time are proposed based on the polynomial function. To derive the guidance commands, we first assume that the acceleration command profile can be represented as a polynomial function with unknown coefficients. After that, the unknown coefficients are determined to achieve the given terminal constrains. Using the determined coefficients, we can finally obtain the state feedback guidance command. The suggested approach to design the guidance laws is simple and provides the more generalized optimal solutions of the impact angle and time control guidance.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.164.2-164
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• 2001

Sliding mode control (SMC) with variable nonlinear boundary layer is proposed. Two Fuzzy logic controllers (FLCs) are used to decide both boundary layer thickness and nonlinear interpolation using sigmoid function in the boundary layer. The nonlinear interpolation in the boundary layer suing FLC reduces stead state error and chattering. Sigmoid function is used to nonlinear interpolation in the boundary layer sigmoid function parameter with FLC. To demonstrate its performance, the Proposed control algorithm is applied to a simple nonlinear system.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.411-424
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• 2018

Purpose: The purpose of this study is to improve submarine TACM launcher system safety device performance. Methods: In this study, EPLD(Electrically Programmable Logic Device) control and time sharing method to the safety device actuator motor and discrete signal processor in launch control panel were used to resolve unusual performance of safety system. Results: The result of this study are as follows; First, sporadic stopping of safety device actuator motor due to insufficient In-Rush current was resolved. Second, repeat of safety device condition as lock & release due to chattering for motor activating was resolved. Third, simultaneous release function for safety device actuator was available. Conclusion: The unusual performance of function for submarine TACM launcher system was overcame by applying EPLD control and time sharing method. The suggestions were proved by performance test in the pressure chamber. The results of this study enhanced survivability of ${\bigcirc}{\bigcirc}{\bigcirc}$ class submarine from enemy torpedo.

• Wind and Structures
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• v.12 no.1
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• pp.63-76
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• 2009

The vortex-induced vibration of an ${\sqcap}$-shaped bridge deck sectional model is studied in this paper via the wind tunnel experiment. The vibratory behavior of the model shows that there is a transition of the predominant vibration mode from the vertical to the rotational degree of freedom as the wind speed increases gradually or vice versa as the wind speed decreases gradually. The vertical vibration is, however, much weaker in the latter case than in the former. This is a phenomenon which is difficult to model by existing parametric models for vortex-induced vibrations. In order to characterize the aeroelastic property of the ${\sqcap}$-shaped sectional model, a time domain force identification scheme is proposed to identify the time history of the aeroelastic forces. After the application of the proposed method, the resultant fluid forces are re-sampled in dimensionless time domain so that reduced frequency response function (RFRF) can be obtained to explore the properties of the vortex-induced wind forces in reduced frequency domain. The RFRF model is proven effective to characterize the correlation between the wind forces and bridge deck motions, thus can explain the aeroelastic behavior of the ${\sqcap}$-shaped sectional model.