• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.140.1-140.1
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• 2011

한국우주전파관측망(KVN)은 2009년 후반기부터 단일경으로 연구관측을 계속하면서 이제 22/43 GHz 대 VLBI로서의 연구관측을 앞두고 있다. 여기에서는 KVN의 중요한 연구분야의 하나인 점근적색거성에서 전행성상성운에 이르기까지 진화과정에 대한 KVN 단일 경 관측연구룰 소개하고 앞으로의 VLBI 연구방향을 소개하고자 한다. 단일경 연구에는 SiO 및 H2O 메이저선 동시관측에 의한 점근적색거성과 후점근적색거성 등에 대한 서베이 및 상대적으로 강한 메이저선 강도를 보이는 각 단계별 관심 천체에 대한 시간 모니터링 관측 결과를 소개한다.

• The Science & Technology
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• v.22 no.8 s.243
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• pp.8-18
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• 1989

행정개혁위원회가 과기처 행정체제를 축소 조정키로 성안, 이를 대통령에게 보고함에 따라 과총회원단체를 중심으로 과학기술계는 동위원회의 결정방향이 경쟁적으로 과학기술정책을 강화해 나가는 세계명국의 추세에 역행하는 처사로 인식, 성명서와 건의서를 계속 발표하고 있다. 이달 긴급 특집은 과학기술정책, 기초과학 및 과학기술 전문언론인의 시각에서 이 문제의 심각성을 다루었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.945-947
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• 2021

Canny Edge Detection은 필터와 방향벡터를 이용한 대표적인 외곽선 추출 알고리즘으로서 대부분의 외곽선 추출 연구에서 이를 변형하여 사용한다. 그러나 본 논문에서는 외곽선 추출의 전처리 과정으로서 이미지에서의 잡음을 제거하는 알고리즘과 이를 바탕으로 외곽선을 더욱 효율적으로 추출할 수 있는 독창적인 알고리즘을 제시한다.

• Journal of the Korean Vacuum Society
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• v.5 no.3
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• pp.199-205
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• 1996

InGaAs eqitaxial layers have been selectively grown on patterned GaAs(100) substrates by chemical beam epitaxy (CBE) using triethylgallium (TEGa), trimethylindium (TMIn), and unprecracked monoethylarsine (MEAs). Facet growth of InGaAs epilayers has also been investigated at the various growth temperatures and Si4N4 dielectric pattern directions. In [011] jirection of mask, the change from (311), (377) and (111) facets to (311) facet with increasing growth temperature was observed. In [011] direction, however, the change from (011) and (111) facets to (111) facet with increasing growth temperature was observed. These results are attributed to the sidewall growth caused by different surface migration lengths of reactants. The formation of U-shaped (100) top surface is also discussed in terms of dangling bond model.

• Spatial Information Research
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• v.20 no.6
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• pp.69-76
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• 2012

In this study, we derived the characteristics of the geo-spatial information industry by using input-output analysis. For this analysis, we classified the geo-spatial information industry and reorganized the input-output table. And we derived the production inducement coefficient, index of the power of dispersion and index of the sensitivity of dispersion in the geo-spatial information industry. We confirmed that geo-spatial information industry has a small production inducement coefficient and a great forward linkage effect. Based on these facts, we suggested the strategy direction as follows: 1) building the industrial eco-system, 2) managing both advance and applicability enhancement, 3) Establishing from a long-term point of view.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.1
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• pp.37-43
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• 2011

In this study, we dealt with the U-City industry in Seoul as a case study for deriving the characteristics of it. Using the interindustry analysis, we made sure that U-City industry has a great forward linkage effect. It means that development of U-City industry have a good effect on the entire industry likewise the infrastructure. In this sense it is important that we have to promote it first. Based on this result, we suggested the strategy direction as follows: 1) Solving the emerging problem, 2) Identifying the roles of public and private sector, 3) Drawing up the plan for supporting.

• Progress in Medical Physics
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• v.5 no.2
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• pp.57-68
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• 1994

Purpose : The purposes are to discuss the reason to measure dose distributions of circular small fields for stereotactic radiosurgery based on medical linear accelerator, finding of beam axis, and considering points on dosimetry using home-made small water phantom, and to report dosimetric results of 10MV X-ray of Clinac-18, like as TMR, OAR and field size factor required for treatment planning. Method and material : Dose-response linearity and dose-rate dependence of a p-type silicon (Si) diode, of which size and sensitivity are proper for small field dosimetry, are determined by means of measurement. Two water tanks being same in shape and size, with internal dimension, 30${\times}$30${\times}$30cm$^3$ were home-made with acrylic plates and connected by a hose. One of them a used as a water phantom and the other as a device to control depth of the Si detector in the phantom. Two orthogonal dose profiles at a specified depth were used to determine beam axis. TMR's of 4 circular cones, 10, 20, 30 and 40mm at 100cm SAD were measured, and OAR's of them were measured at 4 depths, d$\sub$max/, 6, 10, 15cm at 100cm SCD. Field size factor (FSF) defined by the ratio of D$\sub$max/ of a given cone at SAD to MU were also measured. Result : The dose-response linearity of the Si detector was almost perfect. Its sensitivity decreased with increasing dose rate but stable for high dose rate like as 100MU/min and higher even though dose out of field could be a little bit overestimated because of low dose rate. Method determining beam axis by two orthogonal profiles was simple and gave 0.05mm accuracy. Adjustment of depth of the detector in a water phantom by insertion and remove of some acryl pates under an auxiliary water tank was also simple and accurate. TMR, OAR and FSF measured by Si detector were sufficiently accurate for application to treatment planning of linac-based stereotactic radiosurgery. OAR in field was nearly independent of depth. Conclusion : The Si detector was appropriate for dosimetry of small circular fields for linac-based stereotactic radiosurgery. The beam axis could be determined by two orthogonal dose profiles. The adjustment of depth of the detector in water was possible by addition or removal of some acryl plates under the auxiliary water tank and simple. TMR, OAR and FSF were accurate enough to apply to stereotactic radiosurgery planning. OAR data at one depth are sufficient for radiosurgery planning.

• Journal of the Korean Vacuum Society
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• v.18 no.2
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• pp.141-146
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• 2009

PLZT ferroelectric thin films were deposited on Pt/Ti/$SiO_2$/Si substrate with $TiO_2$ buffer layer in between by rf magnetron sputtering method. In order to investigate the effect of Ar/$O_2$ partial pressure ratio on the ferroelectric properties of PLZT thin films, PLZT thin films were deposited at various Ar/$O_2$ partial pressure ratio ; 27/1.5 seem, 23/5.5 seem, 21/7.5 seem and 19/9.5 seem. The crystallinities of PLZT thin films were analyzed by XRD. The surface morphology was observed using FE-SEM. The P-E hysteresis loops, the remanent polarization characteristics and the leakage current characteristics were obtained using a Precision LC. The crystallinity and elaborateness of PLZT thin films were decreased as increasing the oxygen partial pressure ratio. And preferred orientation of PLZT thin films changed from (110) plane to (111) plane. The oxygen partial pressure ratio affects the thin film surface morphology and the ferroelectric properties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.1943-1948
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• 2010

Two kind of $\beta$-SiC powders of different particle sizes (${\sim}1.7\;{\mu}m$ and ${\sim}30\;nm$), containing 7 wt% $Y_2O_3$, 2 wt% $Al_2O_3$ and 1 wt% MgO as sintering additives, were prepared by hot pressing at $1800^{\circ}C$ for 1 h under applied pressures, and then were hot-forged at $1950^{\circ}C$ for 6 h under 40 MPa in argon. All the hot-pressed specimens consisted of equiaxed grains and were developed grain growth after hot-forging. The smaller starting powder was developed the finer microstructure. The microstructures on the surfaces parallel and perpendicular to the pressing direction of the hot-forged SiC were similar to each other, and no texture development was observed because of the lack of massive $\beta$ to $\sigma$ phase transformation of SiC. The fracture toughness (${\sim}3.9\;MPa{\cdot}m^{1/2}$), hardness (~ 25.2 GPa) and flexural strength (480 MPa) of hot-forged SiC using larger starting powder were higher than those of the other.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.446-452
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• 2007

[ $(Pb_{1.1},La_{0.08})(Zr_{0.65}.Ti_{0.35})O_3$ ] thin films on the $Pt/Ti/SiO_2/Si$, $TiO_2(interlayer)/Pt/Ti/SiO_2/Si$ substrate were fabricated by the R.F. magnetron-sputtering method and considered their characteristics depending on $TiO_2$ interlayer. Changing the deposition conditions of $TiO_2$ interlayer, we obtained $TiO_2$ anatase single phase and rutile single phase. PLZT was deposited on these substrates and analyzed by x-ray diffraction(XRD) for there crystallinity and orientation. To investigate $PLZT-TiO_2$, $TiO_2-Pt$ interface, glow discharge spectrometer(GDS) analysis was carried out and we performed electrical measurements for dielectric properties of PLZT thin films. The PLZT thin film on $TiO_2$ anatase interlayer was found to have (110)-preferred orientation and 12.6 ${\mu}C/cm^2$ remaining polarization value.