• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.50-56
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• 2023

INS(Inertial Navigation System) calculates navigation information using a vehicle's acceleration and angular velocity without the outside information. However, when navigation is performed for a long time, navigation error gradually diverges and the performance decreases. To enhance INS's performance, the rotation of inertial measurement unit is developed to compensate error sources of inertial sensors, which is called RINS(Rotational Inertial Navigation System). This paper analyzes the influence of several errors for dual-axis RINS and the shows the results using simulation.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.290-291
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• 2009

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.24-24
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• 2000

위성에 탑재된 지구관측용 카메라는, 지상의 망원경과 같은 원리로, 우주상공에서 지표면 관측을 자동적으로 수행하고 관측정보를 지상으로 전달해 주는 장치다. 이용 목적에 따라 카메라의 해상도 또는 분해능, 관측대역, 관측폭, 위성의 궤도 등의 규격이 결정된다. 고해상도는 카메라 관련 제반 기술 및 경험이 부족한 국내의 여건에 적합한 소형 위성용 고해상도 카메라의 규격을 제시하며 이에 따른 광학 설계와 제작, 조립 및 측정오차를 제시한다.

• Korean Journal of Optics and Photonics
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• v.26 no.4
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• pp.209-216
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• 2015

A new method is proposed for optimal management of the fabrication and assembly tolerance of optical systems. The practical utility of the method is shown by applying it to a wide-angle anamorphic IR optical system. In this method the wavefront error of an optical system is expressed in terms of Zernike polynomials, and the sensitivity of the expansion coefficients to the variation of design parameters is analyzed. Based on this sensitivity analysis, the optimal tolerances of the fabrication parameters are determined and the best compensators for the assembly process are selected. By using this method, one can accurately predict with good confidence the best possible performance of a completed optical system in practice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.96-102
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• 2007

Welding deformation causes critical problems under construction and in use of steel structures by varying the magnitude of the steel structures and deteriorating mechanic strength. Existing method to construct steel structures in civil engineering needs preassembly process for a part of or the whole structures on a broad space to examine the size of structures inevitably varied in the process of welding (assembly process). It leads to waste of time, space and human efforts, worry of safety accidents with the characteristic of the work to be performed on a high place, and non-efficiency and non-economy by using such supplementary equipments as crane. This paper, to remove the needless preassembly process by pre-estimating welding deformation produced under construction of large steel structures, devises a method modeling welded part for applying the equivalence load method and examines the effects of welding sequence and self weight on welding deformation by the method.

• Transactions of the KSME C: Technology and Education
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• v.3 no.4
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• pp.265-271
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• 2015

The bonding process should be achieved in vacuum environment to avoid air bubble. In this study, we studied about pressure uniformity that became an issue in thermo compression bonding usually. Uniform press is realized by the method that use air spring and metal form spring. The concept of uniform press using air spring is removed except pressing direction in the press processing so angle between the vector of pressure surface and the pressure axis is parallel automatically. Air spring compensate the errors of machining and assembly. Metal form compensate the thermal deformation and flatness error.

• Journal of Astronomy and Space Sciences
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• v.18 no.3
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• pp.219-230
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• 2001

Far-ultraviolet IMaging Spectrograph (FIMS) is under development as the main pay-load of the first Korean science satellite, KAISTSAT-4. An extensive sensitivity and error budget analyses of FIMS optical system have been performed. As an way of estimating aggregate effects of all tolerances, a Monte Carlo simulation is used. The simulation result shows that the optical performance required from the science objectives is achieved within the probability higher than 99.9%.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.37.1-37.1
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• 2010

망원경을 사용하여 천체를 관측할 때, 관측할 천체가 있는 위치로 망원경을 정확히 구동하여야 하고, 관측하는 시간 동안 충분히 정확히 추적하여야 한다. 그러나, 망원경은 다양한 재질의 많은 종류의 기계적인 부품들을 조립하여 만들어져 있기에, 필연적으로 기계적인 오차를 가지고 있다. 망원경 구동제어 장치는 수학 연산과 다양한 펄스 특성에 기인한 제어 오차를 가지고 있다. 그리고, 영상을 획득하는 부분은 시간 지연과 상의 왜곡이나 전자적인 잡음의 영향을 받는다. 또한, 바람이나 진동 등 예기치 않은 외부적인 요인에 의한 오차가 유발되기도 한다. 이러한 다양한 요인들로 인하여, 망원경이 천체를 정확히 찾아가고 추적하는 것을 어렵게 만든다. 우리는 자동제어공학에서 사용하는 제어해석 기법을 사용하여 망원경 제어 모형을 만들어 나가고자 한다. 특정 망원경에 있어, 오차 유발에 어느 요인이 가장 큰 영향을 주는지, 또한, 어떤 특성을 조절하고, 어느 정도의 제어 시간 간격을 주어야 하는지 등, 추적오차에 주는 영향들을 정량적으로 분석하고 제어에 반영하여 가장 최적의 제어를 할 수 있도록 하고자 한다. 그 첫번째 시도로, 김해천문대 독일식 적도의 방식 200mm 망원경과 이전 연구에서 개발한 PLC 기반의 망원경 제어 장치(강용우 외, 2008) 및 AP8 CCD 카메라를 사용하여, 지향 및 추적 관측 실험을 하였다. 그 결과를 분석하여 경험적 제어 모형을 만들고, 그 해석을 수행한 내용을 소개하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.9
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• pp.6-12
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• 2011

In this paper, we propose a design method for a reliable and improved field-installable optical connectors(FIOC) which are needed for long-distance and low loss FTTH configuration. To this end, we optimize the angle of splicing between the inner fiber and the field fiber of the FIOC, so that the low loss connection of optical fibers is possible without using any angle alignment tools as well as angled cleavers. More precisely, we set the cutting angle of the inner filber and the field fiber to be $2^{\circ}$ by using an angled cleaver and $0^{\circ}{\sim}1^{\circ}$ by using a general fiber cutter, respectively. Splicing these two optical fibers without any further adjustment, we can keep the insertion loss within 0.3dB and the reflection loss within -60dB.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.