• Journal of the Optical Society of Korea
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• 제9권2호
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• pp.68-73
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• 2005

When aligning catoptric or catadioptric telescopes for space cameras, it is difficult to align precisely if the field of view is large or there are several reflective surfaces. The quantitative knowledge of mirror misalignments greatly helps align a misaligned telescope precisely, and also reduce the alignment time. This paper describes a generalized reverse-optimization alignment solution algorithm using Zernike sensitivity, and proposes the minimum number of fields to take interferograms. This method was successfully applied on a Cassegrain telescope design for Earth observation from space with arbitrary misalignments and a model including some primary mirror deformation.

• Journal of Astronomy and Space Sciences
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• 제26권2호
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• pp.187-198
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• 2009

이 연구에서는 KVN(Korean VLBI Network)의 구경 21m 전파망원경의 변형된 카세그레인식 안테나 광학계에 정렬 어긋남이 있을 때 안테나 이득의 감소, 구경면에서의 상 오차, 그리고 빔 틀어짐 정도를 광선추적방법을 이용하여 수치적으로 계산하였다. 고려한 광학계 어긋남의 종류는 피드의 광축방향 편이, 부경의 광축방향 편이, 피드의 광축과 수직방향 편이, 부경의 광측과 수직방향 편이, 그리고 부경의 기울어짐 등 다섯 가지이다. 먼저 이들 광학계 어긋남이 독립적으로 존재할 경우에 대해서 계산을 하였고, 서로의 어긋남 효과를 상쇄시킬 수 있는 보완관계의 어긋남이 복합적으로 존재하는 경우에 대해서도 계산을 하였다. 광선추적방법을 이용한 계산은 전자기적 효과가 고러되지 않은 순수한 기하학적 계산이지만 이 연구로 효율적인 관측을 위한 KVN 21m 안테나 광학계의 정렬이 가능할 것으로 기대된다.

• Journal of the Optical Society of Korea
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• 제6권3호
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• pp.121-127
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• 2002

The operating principal of a ring laser gyroscope depends on the phase difference for the counter-propagating waves within a closed path. The reflecting mirrors mounted on the monoblock form the traveling waves. The manufacturing accuracy of the monoblock influences the traveling path of ray, the sensitivity of laser resonator for misalignments, and diffraction losses. A 3 $\times$ 3 ray transfer matrix was derived for optical components with centering and squaring errors in a ring resonator. The matrix can be utilized to predict the optical ray paths on the basis of the manufacturing errors of the monoblock as well as the misalignment of mirrors. Then the distance and orientation (o. slope) at the arbitrary plane inside the resonator along the ideal optical path can be calculated from the chain multiplication of the ray transfer matrix for each optical component in one round trip. We also show that the counter-propagating rays In a ring resonator with errors does not coincide in each round trip, which results in gain difference between two beams, and how these errors can be adjusted through the alignment procedure. Finally this 3 $\times$ 3 ray matrix formalism can be used to calculate the beam size and its displacement from the optical axis and the deviation at the diaphragm.

• 한국항공우주학회지
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• 제47권8호
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• pp.574-581
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• 2019

본 논문에서는 추력비정렬 및 발사체 횡방향 무게중심 오프셋에 의한 유도 성능 영향성에 대해서 다루었다. 민감도 분석 방법과 몬테카를로 시뮬레이션 방법을 적용하여 추력비정렬 및 횡방향 무게중심 오프셋에 의한 궤도 투입 오차 변화를 계산함으로써 영향성을 분석하였다. 추력비정렬 및 횡방향 무게중심 오프셋에 의한 영향을 보상하기 위한 방안으로서 적분제어기를 추가하는 방법과 Saturn-V 발사체의 비정렬 보상 알고리듬인 SMC 방법의 적용을 고려해 보았고 몬테카를로 시뮬레이션을 통해 효용성을 평가하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1749-1752
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• 2007

The Near to Eye Display (NED) solves the problem of having a display larger than a small portable device. The virtual image of the NED is created using a microdisplay and imaging optics. It is important that the optics does not interfere with the human visual system and that the device is light, compact and easy to wear. In this paper the principles of a biocular NED, which is based on a novel diffractive Exit Pupil Expander (EPE), are presented. The optical system is compact and intrinsically free from distortions and misalignments.

• 항공우주시스템공학회지
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• 제13권4호
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• pp.26-36
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• 2019

고해상도 지구 관측위성에서는 광학 부품간 정밀한 위치 정렬도가 요구된다. 그러나, 가혹한 위성 발사환경 및 우주환경 같은 외부 요인에 의해 광부품의 정렬오차가 발생한다. 이러한 정렬오차에 의해 저하된 영상품질을 보상하기 위해 포커스 메커니즘이 적용된 위성광학계의 설계가 필요하다. 본 논문에서는 위성카메라 정렬오차 보상이 가능한 목표광학계의 제작 및 성능 실험에 대한 연구를 수행하였다. 먼저 설계된 목표광학계를 제작/조립/정렬하였으며, 이 완료된 목표 광학계를 사용하여 영상 촬영 실험을 수행하였다. 영상 촬영 실험은 포커스 메커니즘에 의한 상의 변화를 이미지로 확인하는 실험과 오토콜리메이터를 이용하여 USAF 타깃을 촬영해 MTF를 분석하는 실험을 수행하였다. 실험 결과를 통해 포커스 메커니즘을 통하여 정렬오차를 충분히 보상할 수 있음을 확인하였으며, 궤도상에서 정렬오차를 보상할 수 있는 리포커싱의 기초자료를 확보하였다.

• 도시과학
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• 제6권2호
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• pp.11-16
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• 2017

Giuseppe Terragni was one of the founding member and a leading Italian Rationalist pursued a new and more rational synthesis between the nationalistic values of Italian Classicism and structural logic of the machine age. Casa Giuliani Frigerio, a four-story apartment housing in Como, is one of his last major work and is worth to investigate the composition of facades in terms of ambiguity. Unlike the Casa del Fascio, it is never possible to read an priori whole and to allow static and unified readings in a traditional alignment. Due to its misalignments found within the facades of Casa Giuliani Frigerio, it is evident to present unstable and disjunctive readings. These distinctive facades are read as layers applied onto some equally unstable underlying layer and form an ensemble of unexpected unity.

• 대한기계학회논문집A
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• 제28권6호
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• pp.677-684
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• 2004

Plastic and creep deformations of solder joints during thermal cycling are the main factors of misalignments and power losses in optical telecommunication components. Furthermore, the increased mismatch between solder Joint-bonded areas may cause severe failure in the components. Darveaux's creep model was implemented into a finite element program (ABAQUS) to simulate creep response of solder. Based on the finite element results, thermal fatigue reliability was predicted by using various fatigue life prediction models. Also, the effects of ramp conditions, dwelling time, and solder joint-embedding materials on the reliability were investigated under the thermal cycling conditions of the Telcordia schedule (-40∼75$^{\circ}C$).

• 전자공학회논문지D
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• 제34D권1호
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• pp.49-54
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• 1997

We proved the feasibiltiy of a parallel optical interconnection technique using single GRIN (graded-index) rod lens as an intermediate coupling device, which increases the working distance and makes packaging easy. The proposed technique shows relatively less dependency on misalignments. In this paper, for convensience of experiments, we applied this method to 4-channel coupling between two fiber arrays, and compared it with butt-coupling and the method of using ball lens. The comparison shows the feasibility of adopting the proposed method to the parallel interconnection between a laser diode array and an optical fiber array.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.292-294
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• 2006

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.