• 한국정밀공학회지
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• 제23권8호
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• pp.72-79
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• 2006

We measured grating pitch standards using optical diffractometry and analyzed measurement uncertainty. Grating pitch standards have been used widely as a magnification standard for a scanning electron microscope (SEM) and a scanning probe microscope (SPM). Thus, to establish the meter-traceability in nano-metrology using SPM and SEM, it is important to certify grating pitch standards accurately. The optical diffractometer consists of two laser sources, argon ion laser (488 nm) and He-Cd laser (325 nm), optics to make an incident beam, a precision rotary table and a quadrant photo-diode to detect the position of diffraction beam. The precision rotary table incorporates a calibrated angle encoder, enabling the precise and accurate measurement of diffraction angle. Applying the measured diffraction angle to the grating equation, the mean pitch of grating specimen can be obtained very accurately. The pitch and orthogonality of two-dimensional grating pitch standards were measured, and the measurement uncertainty was analyzed according to the Guide to the Expression of Uncertainty in Measurement. The expanded uncertainties (k = 2) in pitch measurement were less than 0.015 nm and 0.03 nm for the specimen with the nominal pitch of 300 nm and 1000 nm. In the case of orthogonality measurement, the expanded uncertainties were less than $0.006^{\circ}$. In the pitch measurement, the main uncertainty source was the variation of measured pitch values according to the diffraction order. The measurement results show that the optical diffractometry can be used as an effective calibration tool for grating pitch standards.

• 한국정밀공학회지
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• 제21권5호
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• pp.38-45
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• 2004

As optical communication is being substituted for telecommunication, the demand of a large variety of fiber optic components is increasing. V-groove substrates, one of the module components, are used to connect optical fibers to optical planar circuits and to arrange fibers. Their applications are multi-channel optical connectors and optical waveguide fiber coupling, etc. Because these substrates are a critical part of the splitter in a multiplexer and a multi fiber connector, precise and reliable fabrication process is required. For precisely aligning core pitch between fibers, machined core pitch tolerance should be within sub-microns. Therefore, these are generally produced by state-of-the-art micro-fabrication like MEMS. However, most of the process equipment is very expensive. It is also difficult to change the process line for custom designs to meet specific requirements using various materials. For various design specifications such as different values of the V angle and low-priced process, the fabrication method should be flexible and low cost. To achieve this goal, we have suggested a miniaturized machine tool with high accuracy positioning system. Through this study, it is shown that this cutting process can be applied to produce V-groove subtracts. We also show the possibility of using a miniaturized machining system for producing small parts.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.73-78
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• 2006

The occurrence of detrimental substances in the paper machine leads to reduced economic performance of paper mills through reduced capacities due to increased paper breaks and cleaning times. In this article the latest generation of BASF's laser optical pitch particle counter is employed in the examination of a paper mill operating two paper machines and using a mixture of thermo-mechanical pulp and recycled fibres. The potential of the new instrument to differentiate between particles on the basis of size and chemical composition is discussed. In addition, direct evidence of the periodic and locational variation of detrimental substances in the paper machine is given. Finally, an example of the application of BASF's laser optical pitch particle counter in the selection of a suitable fixative system for a complex furnish is presented.

• 정보저장시스템학회논문집
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• 제6권1호
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• pp.12-17
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• 2010

Thermally-assisted magnetic recording (TAMR) is a potentially promising approach to increase the storage density of hard disk drive (HDD). However, TAMR has some issues such as temperature effects, media problems, thermal deformation and light delivery. In this research, we focused on light delivery. One of the powerful methods to deliver the light from laser diode to recording medium is the use of an optical fiber and a specially designed prism. However, the TAMR with optical fiber may have some flyability problems induced by the mounted optical fiber and prism. Also, the TAMR suspension using an optical fiber has high vertical and pitch stiffness. Therefore, p-torque is greatly increased by the optical fiber. Also, flying height (FH) of the slider with TAMR suspension can be largely changed by p-torque. Therefore, in this paper, we focus on the pitch static attitude (PSA) tolerance and the FH by PSA of the TAMR suspension. The FH is investigated using various errors and the PSA tolerance for TAMR suspension is proposed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.519-523
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• 2009

This paper presents the analysis of pitch static attitude (PSA) in thermally assisted magnetic recording (TAMR) suspension. The TAMR suspension using an optical fiber has high stiffness such as vertical, pitch and roll. Therefore, P-torque is greatly increased by the optical fiber. Also, flying height (FH) of the slider with TAMR suspension can be largely changed by PSA. In this paper, we focus on the FH by PSA of TAMR suspension. The FH is investigated using various PSA and proper PSA is proposed.

• 한국소음진동공학회논문집
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• 제20권3호
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• pp.229-234
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• 2010

This paper presents the analysis of pitch static attitude(PSA) in thermally assisted magnetic recording(TAMR) suspension. The TAMR suspension using an optical fiber has high stiffness such as vertical, pitch and roll. Therefore, P-torque is greatly increased by the optical fiber. Also, flying height(FH) of the slider with TAMR suspension can be largely changed by PSA. In this paper, we focus on the FH by PSA of TAMR suspension. The FH is investigated using various PSA and proper PSA is proposed.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.73-74
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• 2008

• 한국광학회지
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• 제19권6호
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• pp.422-428
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• 2008

본 논문에서는 툴 영향 함수(Tool Influence Function)를 이용한 피치(pitch)툴의 정량적 물질 제거 제어 기법에 대하여 기술하였다. 피치 툴은 뛰어난 표면 거칠기를 생성시키는 반면 툴의 물질 변형이 상대적으로 크고 물질제거가 어렵기 때문에 일반적으로 숙련된 가공 기술자에 의한 정성적 연마 기법으로 간주되었다. 하지만 이러한 피치 툴을 이용한 수치모사 및 실험을 수행한 결과, 정량적 피치 툴 연마 기법이 가능하다는 것을 알 수 있었다. 실험과 수치모사에 의한 물질 제거 형상은 약 79%의 정확도로 일치하였다. 또한 직경 280 mm의 평면가공에 대한 수치모사 단계에서 5번의 모의 가공 후 p-v(peak to valley) $1{\mu}m$의 최초 형상오차를 168 nm까지 낮추는 결과를 얻을 수 있었다.

• 한국세라믹학회지
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• 제33권12호
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• pp.1387-1393
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• 1996

A study on mesophase pitch as a matrix precursor of carbon fiber reinforced carbon (C/C) composite has been recently presented. This study is concerned with the production of mesophase pitch as matrix precursors for C/C composite from coal tar pitch. A commercial coal tar pitch was heat-treated at 25$0^{\circ}C$ for 2 hours to remove low molecular weight fraction from the pitch then increasing the temperature of the pitch to between 350~45$0^{\circ}C$ to produce mesophase pitch. The pitch was continuously stirred during this time and nitrogen gas was continuously bubbled through the pitch. Spherical and bulk mesophases were formed in the pitch after heat-treatment,. Parent and mesophae pitches were characterized by elemental analysis coke yield solubi-lity in tetrahydrofuran and hexane and an optical microscopy to measure the mesiophase content. It was neces-sary to produce C/C composite that a mesophase pitch with about 30-40 vol% mesophase spherulites can be infiltrated into a fiber preform without a filter effect as a matrix precursor conditions. This condition was satisfied with mesophase pitch heat treated at 40$0^{\circ}C$ for 2 hours. The other heat treatment conditions showed the nuclei of mesophase or bulk mesophae which were not satisfied with the matix precursor condition.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.333-336
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• 2008

We have studied on optical properties of advanced S-IPS with a fine pitch electrode and a new finger design. Transmittance of panel increases with decreasing of width and angle of finger electrode. In order to improve transmittance, fine pitch electrode of ${\sim}2{\mu}m$ and rubbing angle of 10 degree have been adopted. Various optical performances are defined as the function of finger design and field intensify across the IPS pixel electrodes. We have developed the advanced electrode structures with a high performance. As a result, the optical properties of 42" full HD with 120Hz frequency shows high transmittance over 5%, contrast ratio of 1800:1, gray-to-gray response time of 4.4ms, respectively. And also we have studied that the moving picture quality of IPS LCD is related with design parameters of IPS cells and finger shape.