• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.179-182
• /
• 1998

Carrier recovery, the process of recoverying the carrier in receiver, removes the phase difference between VCO and the received signal. However, the conventional structure of carrier recovery cannot be applied to multi-level QAM demodulator because of the increasing decision interval and the complexity of control as the number of symbol increases. In this paper, we suggest a new carrier recovery algorithm using $\theta-matching$ algorithm for multi-level QAM demodulation to overcome this problem and analysis the performance and implement it.

• Journal of applied mathematics & informatics
• /
• 제14권1_2호
• /
• pp.365-376
• /
• 2004

The purpose of this study is to show that the accuracy of the interpolation method can be at least doubled when additional smoothness requirements and boundary conditions are met. In particular, as a basis function, we are interested in using a conditionally positive definite function $\Phi$ whose generalized Fourier transform is of the form $\Phi(\theta)\;=\;F(\theta)$\mid$\theta$\mid$^{-2m}$ with a bounded function F > 0.

• 전기화학회지
• /
• 제2권1호
• /
• pp.23-26
• /
• 1999

백금$(Pt)/0.1M\;H_2SO_4$, 전해질 계면에서 교류임피던스 측정과 위상이동 방법을 사용하여 Langmuir 흡착등온식을 정성적으로 해석하였다. 위상이동$(\phi)$은 음전위(E<0)와 주파수(f)에 따르며, Pt 일전극(음극)에 흡착된 수소원자$(H_{ads})$의 표면피복율$(\theta)$에 반비례한다. 중간주파수대$(1\~100 Hz)$에서 위상이동 변화$(\phi\;vs.\;E)$는 Langmuir 흡착등온식$(\theta\;vs.\;E)$의 계산과 해석에 사용할 수 있는 실험적인 방법이다. $Pt/0.1M\;H_2SO_4$ 전해질 계면에서 흡착평형상수(K)와 표준자유에너지$({\Delta}G_{ads})$는 각각 $3\times10^{_4}$와 20.1kJ/mol이다.

• 한국광학회지
• /
• 제10권5호
• /
• pp.364-368
• /
• 1999

일반적으로 LSU(Laser Scanning Unit)는 LD모듈(Laser Diode, 콜리메이팅 렌즈, 슬릿), 실린더 렌즈 고속회전하는 PM(Polygon Mirror), f$\theta$렌즈와 같은 광부품들과 이들을 취부하는 Housing으로 구성되어져 있다. 먼저 본 논문에서는 당사에서 자체적으로 광설계된 LSU 시작품(시작(試作品)을 측정/평가하기 위해 평가항목들에 관해 살펴 보았다. 당사에서 시제작된 LSU의 특징은 LSU의 핵심부품인 f$\theta$렌즈가 2단가압형 저압사출방식으로 제작되었다는 것이다. LSU의 평가항목들은 BSH(Beam Scan Head)를 LMC(Linear Motion Controller)위에 장착해서 비교적 간단히 측정 할 수 있었고, 측정결과 600DPI(Dots Per Inch) 성능을 만족함을 확인할 수 있었다.

• 한국기계가공학회지
• /
• 제20권9호
• /
• pp.20-27
• /
• 2021

The effective surface of lens was studied for injection molding process and to enable mass production of f-theta lens, which is the primary component of laser printers and laser scanning systems. Injection molding is an optimal method if f-theta lens is frequently used for the mass production of plastic lenses as an aspherical lens that requires ultra-precision. A uniform injection molding system should be maintained to produce high quality lenses. Additionally, to maintain these injection molding systems, various factors such as pressure, speed, temperature, mold and cooling should be considered. However, a lens with the optical characteristics of an f-theta lens can be obtained. The effects of melting and cooling of plastic resin on the effective surface of f-theta lenses and the numerous factors that affect the injection molding process were studied.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.927-930
• /
• 1998

This paper presents a new method for reconstructing 3 dimensional object model using a zoom camera. The proposed method uses zoom images to find the distance(D) between camera and object. Also the method uses images obtained around the object to find an $angle(\theta)$ between two connected planes of the object. With the D and $\theta,$ we can reconstruct the real sized 3-D model of object with less errors without stereo camera or rangefinder.

• 한국정보통신학회논문지
• /
• 제20권3호
• /
• pp.513-518
• /
• 2016

본 논문은 라인 레이저 기반 3차원 스캐너에서 투영을 이용한 고속 메쉬 생성 방법을 제안한다. 3차원 공간에서의 메쉬를 생성하기 위한 가장 알려진 방법은 3차원의 점을 4차원으로 변환하고 4차원 컨벡스 헐(convex hull)을 구축하는 방법을 활용한다. 이런 방법은 많은 수의 점 데이터를 가지는 3D 스캔 결과에서는 메쉬를 만들 때 시간이 많이 요구된다. 제안하는 방법에서는 라인 레이저 스캐너에서 중간에 얻어지는 (${\theta}$, y, z)축의 점 정보를 투영하여 얻어진 (${\theta}-y$) 2차원 깊이 지도를 메쉬 생성에 활용한다. 제안된 방법은 2D 영역에서 수행되기 때문에 메쉬를 구성하는 시간이 상당히 단축된다. 제안하는 방법을 평가하기 위해서 라인 레이저 기반 스캐너의 중간 데이터를 이용하여 실험을 진행하였다. 실험 결과는 제안된 방법이 기존방법보다 고속 메시 생성에서 우수함을 보여준다.

• Steel and Composite Structures
• /
• 제30권2호
• /
• pp.81-96
• /
• 2019

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (${\sigma}_{{\theta},pre}$) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of ${\sigma}_{{\theta},pre}$. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (${\sigma}_{\theta}$) in the core tube. Together with the ${\sigma}_{{\theta},pre}$ in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and ${\sigma}_{{\theta},pre}$ on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the ${\sigma}_{{\theta},pre}$ can significantly affect the hysteretic behavior of a TTBRB.

• 마이크로전자및패키징학회지
• /
• 제7권2호
• /
• pp.37-42
• /
• 2000

저유전상수 폴리머와 $SiO_2$위에 형성된 Al/Ti박막의 우선방위에 대해 비교하였다. DC 마그네트론 스퍼터를 이용하여 50 nm 두께의 Ti과 500 nm의 Al-1%Si-0.5%Cu(wt%) 합금 박막을 저유전상수 폴리머와 $SiO_2$기판위에 증착하였다. Al의 우선방위는 XRD $\theta$-2$\theta$와 rocking curve로 측정하였고, Al/Ti박막의 미세조직은 투과전자현미경 (TEM)으로 관찰하였다. 저 유전상수 폴리머 위에 증착된 Al/Ti박막은 $SiO_2$위에 증착된 것보다 낮은 우선방위를 가졌다. 단면 TEM으로 Ti을 관찰한 결과, $SiO_2$위의 Ti의 결정립은 기판에 수직하게 성장하였으나 저유전상수 폴리머 위의 Ti 결정립은 등축정으로 성장하였으며, 저유전상수 폴리머위의 Al/Ti박막이 낮은 우선방위를 갖는 이유는 Ti 미세조직 때문이었다.

• 한국운동역학회지
• /
• 제25권3호
• /
• pp.241-248
• /
• 2015

Objective : The purpose of this study was to investigate the theta on the components of ground reaction force according to the ground conditions during gait. Method : Six healthy women(mean age: 22 yrs, mean height: $166.14{\pm}2.51cm$, mean body weights: $56.61{\pm}4.58kg$) participated in this study. The medial-lateral GRF(Fx 1), anterior-posterior GRF(Fy 1, Fy 2), vertical GRF(Fz 1, Fz 2, Fz 3), and impact loading rate were determined from time function and frequency domain. Also, GRF theta were time function and forces. Results : Fx 1, Fy 1 and Fy 2 of stair descending showed significant statistically higher forces than that of level walking, and ascending. Fz 1 of stairs descending showed significant statistically higher forces than that of level walking and stairs ascending(theta $88.62^{\circ}$). Also, Fz 2 of level walking showed significant statistically higher forces than that of stairs ascending and descending(theta $65.78^{\circ}$). Fz 3 of stairs ascending showed significant statistically higher forces than that of level walking and stairs descending($65.26^{\circ}$). Impact loading rate of stairs descending showed significant statistically higher forces than that of level and ascending walking. The GRF showed similar correlation with GRF theta(r=.603) according to the ground conditions during gait. Conclusion : These results suggest that the GRF theta can be used in conjunction with a gait characteristics, prediction of loading rate and dynamic stability.