• Journal of KIISE:Databases
• /
• v.27 no.2
• /
• pp.216-226
• /
• 2000

This paper suggests a new access path, hashed B-tree which is an efficient access method for integrity checking. Hashed B-tree is based on the observation that most query patterns in enforcing integrity constraints are point queries. Hashed B-tree compresses the key by hashing procedure, which reduces the height of tree and results in fast node search. This method has the advantages such as it can be implemented easily and use the B-tree concurrency control and recovery algorithm with minor modifications.

• Proceedings of the IEEK Conference
• /
• 2003.07b
• /
• pp.1097-1100
• /
• 2003

Tunable thermo-optic filter for WDM system was designed and fabricated. The basic structure of the filter was a Fabry-Perot resonator and the center cavity layer was poly-Si. Quardraple layers of low and high refractive index materials were used as DBR mirrors. Tuning and transmission efficiencies was measured and compared with the simulation results. Tuning range of 9.4 nm can be obtained by 64.7$^{\circ}C$ temperature changes and tuning efficiency was 0.144nm/K. The filter is to be assembled onto the micro optical bench with fiber optical path.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2000.11a
• /
• pp.136-139
• /
• 2000

Controller refinement scheme to improve the performance of a conventional system automatically in frequency domain is proposed. The controller automatic tuning method features using experimental frequency responses of the conventional closed-loop system, the conventional controller, and the improved closed-Imp system; instead of poorly modeled plant due to non-linearities and disturbances. The improved closed-loop system characteristics is automatically acquired by the conventional closed-loop system characteristics and the proposed performance index in system bandwidth. And the proper controller is realized by least squares approximation in frequency domain. To testify the usefulness of the approach, experimental results of robot path-tracking control applied with various controllers is used, and then is analyzed with respect to a equivalent proportional controller. Experimental results and analytic results are well-matched.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.1
• /
• pp.65-70
• /
• 2008

The shape and the material of a reflective sheet affect the amount and the range of retroreflection on incident angle of light, significantly. In this study, the method to determine the shape and the material of the reflective sheet is introduced for the maximum retroreflection. Since the microprism shape with an equilateral triangle base has been used widely, the shape optimization of the microprism shape is carried out. The path of the light within the prism is geometrically calculated to find the relationship between incoming and outgoing light to and from a microprism. The optimal shape of a microprism found by the simulation has almost same figure with the one being used in industry for the maximum retroreflection. It is also found that the refraction index of the reflective sheet is another parameter to control for maximum retroreflection and the range of retroreflection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.04a
• /
• pp.461-466
• /
• 2012

Customers want to have more convenient and comfortable vehicle. Motor-on-caliper EPB(Electrical Parking Brake) System is one of the new systems for customer's convenience. It is applied for Midsize vehicle for reducing weight/price compared to cable puller type EPB. In this paper we studied sound quality improvement of motor-on-caliper EPB system. We developed the sound quality index and suggested the interior sound quality target value. To meet the target value cascading target was also suggested. EPB motor vibration level & sound radiation level, vibro-acoustic transfer function level from EPB to interior was defined. To find out effective way of sound quality improvement and find cascading target, TPA(Transfer Path Analysis) was carried out.

• Korean Institute of Interior Design Journal
• /
• v.24 no.2
• /
• pp.108-116
• /
• 2015

The probability of visual perception occurrence varies in case the expectation of using each unit space of which the whole space consists because the size of space subject to analysis is very large or the organization is complicated in the analysis of spatial visual configuration. Therefore, it is necessary to compensate space analysis and index measurement by applying weight to the point of view for the probability of experiencing space. This study proposed a method of analyzing visibility ratio by applying the integration of space syntax theory as weight, and grasped the effect in comparison with the visibility ratio when weight was not applied.

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10a
• /
• pp.219-221
• /
• 2000

본 논문은 객체 관계형 실시간 DBMS인 Tachyon이 제공하는 데이터 타입과 객체지향 질의의 설계 및 구현을 기술한다. Tachyon은 고성능 데이터 처리를 지원하는 객체 관계형 메모리상주 데이터베이스 시스템(Main-memory resident ORDBMS)로 Tachyon의 데이터 타입과 SQL은 ANSI SQL 3 draft를 기반으로 설계되었으며, 객체 관계형 질의 처리를 위한 OID 데이터 타입을 추가하였다. Tachyon은 클래스 간의 수직적 관계(상속)와 수평적 관계를 정의하고 조작할 수 있는 객체지향 질의를 통하여 융통성있는 데이터 조작이 가능하며, OID를 기반으로 경로식(path expression)을 이용한 향해 질의(navigational query)를 통하여 죠인(join) 비용을 절감하고, index를 통한 인스턴스 접근 등을 통하여 효율적인 데이터베이스 접근을 시도할 수 있다.

• Journal of the Korean Society of Visualization
• /
• v.17 no.3
• /
• pp.32-38
• /
• 2019

The dynamic stability of swarms is crucial in preventing collisions in clustered flights and safely moving along a defined path. Although there have been many simulation studies on dynamic stability, there have not been many experimental studies using real clusters due to the difficulty in implementation. In this study, we constructed a particle-lattice structure simulating bird flocks or drone swarms, and conducted experiments within turbulent flow. We identified a criterion that describes dynamically stable particle-lattice structures. The stability increased as this newly defined spatial index increased.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2000.10a
• /
• pp.144-147
• /
• 2000

Controller refinement scheme to improve the performance of a conventional system automatically in frequency domain is proposed. The controller automatic tuning method features using experimental frequency responses of the conventional closed-loop system the conventional controller, and the improved closed-loop system, instead of poorly modeled plant due to non-linearities and disturbances. The improved closed-loop system characteristics is automatically acquired by the conventional closed-loop system characteristics and the proposed performance index in system bandwidth. And the proper controller is realized by least squares approximation in frequency domain. To testify the usefulness of the approach, the path tracking control of robot arm is performed. Experimental results and analytic results are well-matched.

• Structural Engineering and Mechanics
• /
• v.16 no.4
• /
• pp.441-468
• /
• 2003

This paper investigates the structural behavior of modular falsework system under sequential pattern loads. Based on the studies of 25 construction sites, the pattern load sequence modeling is defined as models R (rectangle), L and U. The study focuses on the system critical loads, regions of largest reaction forces, discrepancy between the pattern load and the uniform load, and the warning-system plan. The analysis results show that the critical loads of modular falsework systems with sequential pattern loads are very close to those with the uniform load used in design. The regions of largest reaction forces are smaller than those calculated by the uniform load. However, the regions of largest reaction forces of three models under sequential pattern loads can be considered as the crucial positions of warning-system based on the measured index of loading. The positions of the sensors for the warning-system for these three different models are not identical.