Monte Carlo photon simulation 기법을 사용하여 광추출효율 관점에서 InGaN LED를 분석하였다. InGaN/sapphire 칩의 경우, AlInGaP나 InGaN/SiC 칩에서와는 달리, 칩의 측벽면을 기울여 주는데서 오는 광추출효율 개선 효과는 매우 미미하였다. 이는 InGaN/sapphire 칩의 경우 사파이어 기판의 굴절률 상대적으로 작아서 활성층으로부터 생성된 광자들의 상당량이 기판으로 넘어갈 때 전반사현상으로 말미암아 기판으로 넘어가지 못하고 상대적으로 두께가 매우 얇은 에피택시 층에 갇히기 때문으로 파악되었다. 이와 같은 효과는 epitaxial side down mount의 광추출효율이 크게 개선되지 못하는 원인으로도 작용하게 되는데, epitaxial side down mount의 잠재력을 살릴 수 있는 방안의 하나는 texture된 기판위에 결정층을 성장시키는 것이라고 할 수 있다.

A critical issue in implementing efficient Ethernet passive optical network(EPON) System is the bandwidth allocation algorithm. The overall goal of bandwidth allocation is to effectively and fairly perform scheduling of time slots between ONUs in EPON System. We propose a new algorithm of dynamic bandwidth allocation for improved bandwidth efficiency in EPON system.

One of the most important things in EPON(Ethernet Passive Optical Network) is that ONUs(Optical Network Units) have to share a channel in upstream direction. We proposed a new algorithm of Dynamic Bandwidth Allocation using Multiple LLID(Logical Link IDentifier). We show how to allocate bandwidth in Queues for improving performance from Bandwidth using Multiple LLID.

As a channel is shared in upstream direction, a Dynamic Bandwidth Allocation(DBA) algorithm is necessary for Ethernet Passive Optical Network(EPON) to allocate bandwidths effectively. In this paper, we proposed a algorithm of DBA using a new Proportional Factor and analyzed it.

The doping technique has been well known as method to get various emission color by choosing appropriate fluorescent dyes as a dopant. Usually, red emission of OLED device based on Alg$_{3}$ doped with DCM and rubrene is fabricated. Result that fabricate OLED device was manufactured by various doping density, we looked for the doping ratio of highest luminescent efficiency.

In this paper the conceptual design and development of a compact vertical type soft x-ray microscope is described. This x-ray microscope operates in the water window wavelength region(2.3 ${\sim}$ 4.4nm), where natural contrast between carbon(protein) and oxygen(water) allows imaging of unstained biological material their natural, hydrated environment. Until now, operational x-ray microscopes are based on synchrotron radiation sources, which limit their accessibility. Many biologists would benefit from having the x-ray microscope as a tool among other tools in their own laboratory, For this purpose we introduced the compact vertical type soft X-ray microscope with 50 nm resolution for biomedical application. The compact vertical type soft x-ray microscope is based on a laser plasma x-ray source, doubled ellipsoidal condenser reflective optics, diffractive zone plate optics and MCP coupled with CCD to record an x-ray image.

To study the photon statistics, the total counts probability was measured for the two different optical source : below-threshold with Bose-Einstein distribution, and above-threshold laser with Poisson distribution.

We have presented a comprehensive effective-mass Hamiltonian for strained Wurtzite semiconductors using k${\cdot}$p method and Kane's model. This theoretical groundwork provides a foundation for investigating the electrical and optical properties of wurtzite strained quantum-well lasers.

Variable optical attenuators (VOA) made of low-loss fluorinated polymers are demonstrated which shows a low operating power less than 30 mW due to the superior thermo-optic effect of polymer material and a low insertion loss less than 1.0 dB by incorporating highly fluorinated polymers to reduce the absorption loss at 1550 nm. An attenuator-integrated low-crosstalk polymeric digital optical switch (DOS) is also demonstrated. The switch and attenuator shares a single connected electrode which is controlled by a single current source. Due to the simple structure of the integrated attenuator, the device length is reduced to 1 cm so as to provide low insertion loss of 0.8 and 1.1 dB for 1300 and 1550 nm, respectively. The attenuator radiates remained optical signal on the switch-off branch in order to decrease the switching crosstalk to be less than -70 dB with an applied electrical power of 200 mW.

두께가 있는 물체의 단면영상을 얻는 기술은 현대 영상 기술에서 가장 도전적인 관제 중 하나이다. 특히 광학현미경을 이용해 물체의 단면 영상을 얻기 위해 특정 단면에 초점을 맺을 경우 초점 맺어지지 않은 면으로부터 산란되어오는 빛은 탈 초점잡음(defocused noise)으로 작용한다. 이번 발표에서는 물체의 복소 홀로그램 정보를 광 스케닝 홀로그램 방법을 이용하여 추출하고 그를 수치적인 방법으로 연산해 탈 초점 잡음을 제거한다.