• Journal of Sensor Science and Technology
• /
• v.4 no.1
• /
• pp.3-8
• /
• 1995

n-ITO/p-PSL heterojunction photodetector have been fabricated on the Si wafer by using ITO(indium tin oxide) and PSL(porous silicon layer). They were anodized selectively by using silicon nitride and Ni-Cr/Au and were passivated by using ITO as well as being isolated by using mesa structure. With white light from 0 to 3000 Lux, the photocurrent varied linearly with incident light intensity. The reverse characteristics of fabricated devices were very stable up to a bias voltage of -40V and dark current density was about $40nA/mm^{2}$. When the device was exposed by Xe lamp whose wavelength range from 400nm to 1100nm, the maximum photo responsivity was about 0.6A/W between 600 and 700nm. Variation of the characteristics of fabricated devices after 5 weeks was negligible.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2008.11a
• /
• pp.202-206
• /
• 2008

Recently, as high level of interest for the city regeneration, large-scale projects are planned or being performed such as reconstruction project. These mesa-projects have different characteristics from a single project in the design phase. It is a number of companies involved in design phase of mega-project and principal decision-making entity manage the project from the initial stage of an ongoing business by coordinating an opinions between design companies. The absence of a decision making support system reflected those characteristic causes a variety of problems such as a loss of cost and schedule. Therefore the final object of this paper is to propose a decision making support tool and system interface.

• Journal of Korean Society of Forest Science
• /
• v.88 no.1
• /
• pp.55-62
• /
• 1999

Successful hosting of mesa-events such as the universiade games usually brings many external changes such as more domestic and foreign travelers, image improvement of the host country and region as well as promotion of the local economy through improving the infrastructure for the contest. This longitudinal study analyzed the effects of the winter universiade games, which were held at Muju in 1997, on the hosting rural area, based upon a multidimensional study. As a result, the inhabitants sensed that hosting the winter universiade games had large-scale investment effects on both the tourism industry and the regional development. On the other hand, hosting this kind of event was not quite successful in terms of activating the local economy, and the environment of Togyusan National Park was harmed.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.30A no.12
• /
• pp.51-59
• /
• 1993

A 4${\times}10^{19}cm^{3}$ carbon-doped base AlGaAs/GaAs HBY was grown using carbontetracholoride(CCl$_4$) by atmospheric pressure MOCVD. Abruptness of emitter-base junction was characterized by SIMS(secondary ion mass spectorscopy) and the doping concentration of base layer was confirmed by DXRD(double crystal X-ray diffractometry). Mesa-type HBTs were fabricated using wet etching and lift-off technique. The base sheet resistance of R$_{sheet}$=550${\Omega}$/square was measured using TLM(transmission line model) method. The fabricated transistor achieved a collector-base junction breakdown voltage of BV$_{CBO}$=25V and a critical collector current density of J$_{O}$=40kA/cm$^2$ at V$_{CE}$=2V. The 50$\times$100$\mu$$^2$ emitter transistor showed a common emitter DC current gain of h$_{FE}$=30 at a collector current density of JS1CT=5kA/cm$^2$ and a base current ideality factor of ηS1EBT=1.4. The high frequency characterization of 5$\times$50$\mu$m$^2$ emitter transistor was carried out by on-wafer S-parameter measurement at 0.1~18.1GHz. Current gain cutoff frequency of f$_{T}$=27GHz and maximum oscillation frequency of f$_{max}$=16GHz were obtained from the measured Sparameter and device parameters of small-signal lumped-element equivalent network were extracted using Libra software. The fabricated HBT was proved to be useful to high speed and power spplications.

• Journal of the Korean Geographical Society
• /
• v.37 no.1
• /
• pp.61-74
• /
• 2002

In late 1980s, many suburban cities in Tokyo metropolitan area have tried to construct office parks, such as Makuhari New Town, Minato Mirai 21 to promote knowledge based economy. As the most important player of this mesa project, the local government mobilized local resources from various private sectors. The local government adopted place marketing strategy to attract companies and consumers with thick pocket. The composition of this strategy embraces publicity, uniqueness, centrality of function and information and comfortability for formation of the office park. Headquarters and producer service offices were relocated in the suburban office parks for the first time in the history of modem Tokyo since 1920s. Although it is the ongoing project that encounters some financial difficulties, the office park Project will be a sound foundation for future growth of knowledge-based economy.

• Clinical and Experimental Reproductive Medicine
• /
• v.21 no.3
• /
• pp.247-252
• /
• 1994

Intracytoplasmic sperm injection(ICSI) was known as effective method in treatments of couples who unable to be helped by conventional in vitro fertilization. In 78 treatment cycles of 78 infertile couples using ICSI performed at our infertility clinic between May and August 1994 were analyzed. These patients were classified two groups, andrological factor(AF) and non-andrological factor(non-AF) group. The AF group, which had abnormal sperm physiology, included oligozoospermia, asthenozoospermia, oligoasthenoteratozoospermia(OATS) and microsurgical epididymal sperm aspiration(MESA) patients. The non-AF group, which had abnormal oocyte physiology, included abnormal zona pellucida, poor quality of oocyte and immune factor infertile patients. A single spermatozoon was injected into the ooplasm of 776 metaphase II oocytes. The fertilization rate was 44.6%(346/776) and 319 embryos were transferred. After 73 embryo transfers(93.6% of treatment cycles) 23 pregnancies were estabilshed, i. e. pregnancy rate of 29.4% per started cycle and 31.5% per embryo transfer. Fertilization rate of AF and non-AF group was 46.2% and 35.8%, pregnancy rate was 34.5%(20/58) and 20.0%(3/15), respectively. In order to increase the pregnancy rate, assisted hatching(AHA) has done after lCSl in 47 treatment cycles. Pregnancy rate of ICSI with AHA and without AHA group was 34. 0% (16/47) and 26.9%(7/26), respectively. ICSI was more effective in andrological factor infertility and the pregnancy rate was increased by ICSI with AHA procedure.

• Korean Journal of Materials Research
• /
• v.25 no.1
• /
• pp.1-8
• /
• 2015

This study suggested comprehensive structural characterization methods for the commercial blue light emitting diodes(LEDs). By using the Z-contrast intensity profile of Cs-corrected high-angle annular dark field scanning transmission electron microscope(HAADF-STEM) images from a commercial lateral GaN-based blue light emitting diode, we obtained important structural information on the epilayer structure of the LED, which would have been difficult to obtain by conventional analysis. This method was simple but very powerful to obtain structural and chemical information on epi-structures in a nanometer-scale resolution. One of the examples was that we could determine whether the barrier in the multi-quantum well(MQW) was GaN or InGaN. Plan-view TEM observations were performed from the commercial blue LED to characterize the threading dislocations(TDs) and the related V-pit defects. Each TD observed in the region with the total LED epilayer structure including the MQW showed V-pit defects for almost of TDs independent of the TD types: edge-, screw-, mixed TDs. The total TD density from the region with the total LED epilayer structure including the MQW was about $3.6{\times}10^8cm^{-2}$ with a relative ratio of Edge- : Screw- :Mixed-TD portion as 80%: 7%: 13%. However, in the mesa-etched region without the MQW total TD density was about $2.5{\times}10^8cm^{-2}$ with a relative ratio of Edge- : Screw- :Mixed-TD portion of 86%: 5%: 9 %. The higher TD density in the total LED epilayer structure implied new generation of TDs mostly from the MQW region.

• Journal of the Korean Vacuum Society
• /
• v.7 no.2
• /
• pp.161-168
• /
• 1998

Reactive ion etching process for InGaAs/InP using the CH4/H2 high density inductively coupled plasma was investigated. The experimental design method proposed by Taguchi was utilized to cover the whole parameter range while maintaining reasonable number of actual experiments. Results showed that the ICP power mainly affects surface roughness and verticality of the sidewall, bias power does etch rate and verticality, CH4 gas concentraion does the verticality and etch rate, and the distance between the induction coil and specimen mostly affects the surface roughness. It was also observed that the chamber pressure is the dominant parameter for the etch rate and verticality of the sidewall. The optimum condition was ICP power 700W, bias power 150 W, 15% $CH_4$, 7.5 mTorr, and 14 cm distance, resulting in about 3 $\mu\textrm{m}$/hr etch rate with smooth surfaces and vertical mesa sidewalls.

• Journal of Microbiology
• /
• v.38 no.4
• /
• pp.275-280
• /
• 2000

Pseudomonas sp. S-47 is capable of catabolizing 4-chlorobenzoate (4CBA) as rarbon and energy sources under aerobic conditions via the mesa-cleavage pathway. 4CBA-dioxygenase and 4CBA-dihydrodiol dehydrogenase (4CBA-DD) catalyzed the degradation af 4CBA to produce 4-chlorocatechol in the pathway. In this study, the xylL gene encoding 4CBA-DD was cloned from the chromosomal DNA of Pseudomonas sp. S-47 and its nucleotide sequence was analyzed. The xylL gene was found to be composed of 777 nucleotide pairs and to encode a polypeptide of 28 kDa with 258 amino acid residues. The deduced amino acid sequence of the dehydrogenase (XylL) from strain S-47 exhibited 98% and 60% homologies with these of the corresponding enzymes, Pseudomonas putida mt-2 (XyIL) and Acinetobacter calcoaceticus (BenD), respectively. However, the amino arid sequences show 30% or less homology with those of Pseudomonas putida (BnzE), Pseudomonas putida Fl (TodD), Pseudomonas pseudoalcaligenes KF707 (BphB), and Pseudomonas sp. C18 (NahB). Therefore, the 4CBA-dihydrodiol dehdrogenase of strain S-47 belongs to the group I dehydrogenase involved in the degradation of mono-aryls with a carboxyl group.

• Journal of The Korean Astronomical Society
• /
• v.54 no.4
• /
• pp.129-137
• /
• 2021

It has been established that the acoustic mode parameters of the Sun and Sun-like stars vary over activity cycles. Since the observed variations are not consistent with an activity-related origin, even Sun-like stars showing out-of-phase changes of mode frequencies and amplitudes need to be carefully studied using other observational quantities. In order to test whether the presumed relations between the global seismic parameters are a signature of the stellar activity cycle, we analyze the photometric light curve of HD 49933 for which the first direct detection of an asteroseismic signature for activity-induced variations in a Sun-like star was made, using observations by the CoRoT space telescope. We find that the amplitude of the envelope significantly anti-correlates with both the maximum frequency of the envelope and the width of the envelope unless superflare-like events completely contaminate the light curve. However, even though the photometric proxy for stellar magnetic activity appears to show relations with the global asteroseismic parameters, they are statistically insignificant. Therefore, we conclude that the global asteroseismic parameters can be utilized in cross-checking asteroseismic detections of activity-related variations in Sun-like stars, and that it is probably less secure and effective to construct a photometric magnetic activity proxy to indirectly correlate the global asteroseismic parameters. Finally, we seismically estimate the mass of HD 49933 based on our determination of the large separation of HD 49933 with evolutionary tracks computed by the MESA code and find a value of about 1.2M_☉ and a sub-solar metallicity of Z = 0.008, which agrees with the current consensus and with asteroseismic and non-asteroseismic data.