• 한국광학회:학술대회논문집
• /
• 한국광학회 2000년도 하계학술발표회
• /
• pp.28-29
• /
• 2000

Optical power splitters and/or couplers are important components for optical signal distribution between channels both in wavelength division multiplexing(WDM) systems and photonic integrated circuits(PICs). Since polarization is usually not known after propagation in an optical fiber, passive WDM components have to be polarization insensitivity, Compared to alternatives such as directional couplers or Y-junction splitters, splitters based on multimode interference(MMI) have found a growing interest in recent yens because of their desirable characteristics, such as compact size, low excess loss, wide bandwidth, polarization independence, and relaxed fabrication tolerances$^{(1)}$ . These devices have been fabricated in polymers, silica, or III-V semiconductor materials. A1 $\times$ 4 MMI power splitter on InP materials that were suitable for application in the 1.55-${\mu}{\textrm}{m}$ region$^{(2)}$ . However, the fabrication process of the structure is too complicated and the photolithography tolerance is very tight. Also, a 1 $\times$ 16 InGaAsP/InP MMI power splitter with an excess loss of 2.2dB and a splitting ratio of 1.5dB was demonstrated by using deep etching$^{(3)}$ . The deep etching of the sidewalls through the entire guide layer of the slab waveguide resulted in a number of drawbacks$^{(4)}$ . (omitted)

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.187-187
• /
• 2013

양자점(Quuantum dot, QD)은 0차원 특성을 가지는 구조로 양자 구속 효과로 인하여 bulk와 는 다른 구조적, 광학적, 전기적 특성을 가지고 있다. InAs QD는 size와 barrier의 bandgap 조절을 이용하여 쉽게 bandgap을 바꿀 수 있는 장점이 있어 solar cell, semiconductor laser diode, infrared photodetector 등으로 많은 연구가 이루어지고 있다. 일반적으로 Stranski-Krastanov (SK) mode로 성장한 InAs QD는 보통 GaAs epilayer와의 lattice mismatch (7%)를 이용하여 성장을 하고 이로 인하여 strain을 가지고 있고 QD의 density와 stack이 높을수록 strain이 커진다. 하지만 sub-monolayer (SML) QD 같은 경우 wetting layer가 생기는 지점인 1.7 ML이하에서 성장되는 성장 방식으로 SK-QD보다는 작은 strain을 가지게 된다. 또 QD의 size가 작아 SK-QD보다 큰 bandgap을 가지고 있다. 본 연구에서는 분자선 에피택시(molecular beam epitaxy, MBE)를 이용하여 semi-insulating GaAs substrate 위에 InAs QD를 0.5/1/1.5/1.7/2/2.5 monolayer로 성장을 하였다. GaAs과 InAs의 성장온도와 성장속도는 각각 $590^{\circ}C$, 0.8 ML/s와 $480^{\circ}C$, 0.2 ML/s로 성장을 하였으며 적층사이의 interruption 시간은 10초로 고정하였고 10주기를 성장하였다. Photoluminescence (PL)측정 결과 SML-QD는 size에 따라서 energy가 1.328에서 1.314 eV로 약간 red shift를 하였고 SK-QD의 경우 1.2 eV의 energy정도로 0.1 eV이상 red shift 하였다. 이는 QD size에 의하여 energy shift가 있다고 사료된다. 또 wetting layer의 경우 1.41 eV의 energy를 가지는 것으로 확인 하였다. SML-QD는 SK-QD 보다 반치폭(full width at half maximum, FWHM)이 작은 것은 확인을 하였고 strain field의 감소로 해석된다. 하지만 SML-QD의 경우 SK-QD보다 상대적으로 작은 PL intensity를 가지고 있었다. 이를 개선하기 위해서는 보다 높은 QD density를 요구하게 되는데 growth temperature, V/III ratio, growth rate 등을 변화주어서 연구할 계획이다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
• /
• pp.145-150
• /
• 2003

The present study aims to optimize the performance of the Two-Stage Gas Gun by using the experimentally obtained data. RSM(Response Surface Method) was adopted in the optimization process to find the operating parameter than can maximize the projectile speed with the minimum number of tests. To decide the test points which results can consist of the response surface, 3$^{k}$ full factorial method was used, and the design variables were chosen with piston mass and 2$^{nd}$ driver fill pressure. The response surface was composed by nine test results and consequently the optimization was done with GENOCOP III, inherently GA code, in order to seek the optimal test point. The optimal test condition from the response surface was verified by the experiment. Results showed that the optimization process with response surface can successfully predict the test results fairly well. This study shows the possibility of performance optimization for the experimental facilities using numerical optimization algorithm.

• 한국반도체및디스플레이장비학회:학술대회논문집
• /
• 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
• /
• pp.192-199
• /
• 2003

Film growth of InP and GaAs using TMIn, TMGa, TBAs and TBP is numerically predicted and compared to the experimental results. To obtain exact thermal boundary conditions at the reactor walls, the gas flow and heat transfer are analyzed for full three-dimensional reactor including outer tube as well as the inner reactor parts. The results indicate that the exact thermal boundary conditions are important to get precise film growth rate prediction since film deposition is mainly controlled by the temperature dependent diffusion. The results also show that thermal diffusion plays an important role in the upstream region.

• Animal cells and systems
• /
• 제14권4호
• /
• pp.297-303
• /
• 2010

To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1-2 weeks after the increase of D. rosea. Survey of diel vertica migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I-II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III-IV instars were shown to be higher than other zooplankto based on nitrogen isotope values.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.535-538
• /
• 2004

Zinc Oxide (ZnO) films have attracted considerable attention for transparent conducting films, because of their high conductivity, good optical transmittance from UV to near IR as well as a low-cost fabrication. To increase the conductivity of ZnO, doping of group III elements (Al, Ga, In and B) has been carried out. Transparent conducting films have been applied for optoelectric devices, the development of the transparent conducting thin films on flexible light-weight substrates are required. In this research, the transparent conducting ZnO thin films doped with Aluminum (Al) on polymer substrates were deposited by the RF magnetron suputtering method, and the structural, optical and electrical properties were investigated.

• Journal of Genetic Medicine
• /
• 제15권2호
• /
• pp.97-101
• /
• 2018

Tricho-rhino-phalangeal syndrome (TRPS) is a hereditary disorder characterized by craniofacial and skeletal abnormalities. A mutation of the TRPS1 gene leads to TRPS type I or type III. A 20-year-old male patient visited our neurologic department with chronic fatigue. He presented with short stature, sparse hair, pear-shaped nose, and brachydactyly. Radiologic study showed short metacarpals, metatarsals with cone-shaped epiphyses, hypoplastic femur and hip joint. Panel sequencing for OMIM (Online Mendelian Inheritance in Man) listed genes revealed a de novo heterozygous frameshift mutation of c.1801_1802delGA (p.Arg601Lysfs*3) of exon 4 of the TRPS1 gene. The diagnosis of TRPS can be challenging due to the rarity and variable phenotype of the disease, clinicians should be aware of its characteristic clinical features that will lead a higher rate of diagnosis.

• Nuclear Engineering and Technology
• /
• 제56권1호
• /
• pp.42-47
• /
• 2024

The electrochemical extraction of uranium in ternary low melting LiCl-KCl-CsCl eutectic on inert and reactive electrodes via different electrochemical techniques was investigated. It was established that the electrochemical reduction process of U(III) ions on the inert W electrode was irreversible and proceeded in one stage. On reactive liquid Ga and liquid Cd electrodes the reduction of uranium ions took place with the considerable depolarization with the formation of UGa₂, UGa₃ and UCd₁₁ intermetallic compounds. Thermodynamic characteristics of uranium compounds and alloys were calculated. The conditions for the extraction of uranium from the electrolyte in the form of alloys on both liquid reactive electrodes via potentiostatic electrolysis were found.

• 대한물리치료과학회지
• /
• 제8권2호
• /
• pp.1005-1013
• /
• 2001

The present study was designed to investigate the effect of low power GaAlAs laser on spinal Fos expression related to the anti-nociceptive effect of laser stimulation. Low power GaAlAs laser was applied to either acupoint or non-acupoint for 2 hour under light inhalation anesthesia. Spinal Fos expression in the dorsal horn was compared to that obtained in inhalation anesthesia control group. Furthermore, we analyzed the effect of the local treatment of lidocaine on the spinal Fos expression evoked by low power GaAlAs laser stimulation. The results were summarized as follows: 1. In the normal animals, only a few Fos like immunoreactive(Fos-IR) neurons were evident in the lumbar spinal cord dorsal horn. Similarly, following prolonged inhalation anesthesia, Fos-IR neurons were absent in the dorsal horn of the lumbar spinal cord. In animals treated with laser stimulation, Fos immunoreactive neurons were increased mainly in the medial half of ipsilateral laminae I-III at lumbar segments L3-5. These findings directly indicated that prolonged anesthesia used in this study did not affect the Fos expression in the spinal cord dorsal horn of intact animals and low power laser stimulation dramatically produced Fos expression in the spinal cord laminae that are related to the anti-nociceptive effect of laser stimulation. 2. In acupoint stimulated animals, 10mW of laser stimulation, not 3mW and 6mW intensity, significantly increased the number of Fos immunoreactive neurons in the spinal dorsal horn(p<0.05). However, laser stimulation on acupoint more dramatically increased the number of Fos immunoreactive neurons in the spinal cord rather than laser stimulatin on non acupoint. These result suggested that laser stimulatin on acupoint was more effective treatment to activate the spinal neuron than non acupoint stimulation. 3. The local treatment of lidocaine totally suppressed the activity of spinal neurons that were induced by lower power 1aser stimulation. These data indicated that the anti-nociceptive effect of laser stimulation was absolutely dependent upon the peripheral nerve activity in the stimulated location. In conclusion, these data indicate that 10mW of low power laser stimulation into acupoint is capable of inducing the spinal Fos expression in the dorsal horn related to the anti-nociceptive effect of laser stimulation, Furthermore, the induction of spinal Fos expression was totally related to the peripheral nerve activity in the laser stimulated area.

• Clinical and Experimental Pediatrics
• /
• 제51권1호
• /
• pp.84-88
• /
• 2008

목 적 : 방사선조사는 망막모세포종의 국소적 치료에 효과적인 방법이나 장기 생존자에서 안면발육장애, 각막과 시신경 손상, 이차적인 암의 발생 등의 합병증을 유발하며 방사선조사로 인한 안면발육부전은 나이가 들수록 더욱 심각한 미용적 장애를 초래하고 환자의 삶의 질을 저하시킨다. 진행된 안구 내 망막모세포종과 안와 내 망막모세포종 환자에서 안구적출술과 항암화학치료 및 안와방사선조사를 받은 경우와 받지 않은 경우의 치료성적과 장기예후를 분석하고자 본 연구를 시도하였다. 방 법 : 1985년 10월부터 2006년 12월까지 영남대학교병원에서 망막모세포종으로 진단받은 35명의 환자를 대상으로 병록지를 후향적으로 분석하였다. 안구 내 병변은 Reese-Ellsworth(RE)의 분류에 따라, 안구 외로 진행된 경우는 Grabowski-Abramson (GA)의 분류에 따라 분류하여 RE group III, IV, V인 진행된 안구 내 종양과 GA stage II인 안와 내 종양 환자를 연구 대상으로 하였다. 결 과 : 연구에 포함된 환자는 18명이었고, 진단당시 나이의 중앙값은 27개월(범위 2-69개월), 추적기간의 중앙값은 73.5개월(범위 6-219개월)이었다. 안구 내에 국한된 경우는 6명이었고(RE group III; 2명, IV; 1명, V; 3명) 안와 내로 진행된 경우는 12명이었다(GA stage II). 대상 환아 모두에서 안구적출술을 시행한 후 항암화학치료를 시행하였는데 2001년 이전에는 vincristine, adriamycin, cyclophosphamide, cisplatin, VM-26을, 2001년 이후로는 vincristine, etoposide, carboplatin을 사용하였다. 9명의 환자에서는 국소적으로 방사선조사를 병행하였고, 총 방사선 조사량의 중앙값은 4,500 cGy(범위 3,500-5,000 cGy)이었다. 방사선조사를 병행하여 치료 받은 환아 9명 중 7명은 재발이나 전이 없이 장기생존하였으며, 장기 생존자 모두에서 심한 안면 골격의 비대칭적 발육부전이 나타났다. 방사선조사 없이 치료받은 9명 중에서는 재발이나 전이가 한명도 없이 모두 장기생존하였으며, 안구적출술 이후 인공안와삽입물을 삽입하였으며 안면 골격 발달은 모두 대칭적으로 정상 발육을 하였다. 결 론 : 시신경의 절제면을 침범하지 않은 안와내에 국한된 망막모세포종의 치료에 있어 방사선조사를 제외하고 안구적출술, 항암화학치료, 국소적 치료를 병행함으로써 높은 생존율을 유지하면서 안면발육부전과 같은 심각한 부작용을 줄여 삶의 질을 향상시킬 수 있을 것으로 생각된다. 그러나 시신경의 절제면을 침범한 경우에는 재발의 가능성이 있으므로 후기 후유증의 위험이 있더라도 안구적출술 후 방사선조사와 항암화학치료를 병행한 치료를 시행함으로써 생존률을 높일 수 있을 것으로 생각된다.