• Journal of the Korean Chemical Society
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• v.25 no.6
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• pp.367-375
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• 1981

Single crystals of Potassium Sulfate ($K_2SO_4$) have been grown from the saturated solution by the evaporation method at the optimum conditions. Radiation damages in the crystal by ${\gamma}$-irradiation of about $12{\times}10^6$ Roentgen have given rise to paramagnetic centers or paramagnetic defects. Electron spin resonance (ESR) spectra of the centers are obtained with the X-band EPR spectrometer at room temperature. The ESR peaks of the paramagnetic species are found to be anisotropic but the peak of $SO_3-$ radical is an isotropic of Gaussian shape at g = 2.0036. A number of ESR spectra of the crystal for angular variation of the anisotropic peaks are recorded at various orientations of rotation about a, b and c crystallographic axes respectively. The g-values are calculated from the line position between anisotropic peaks and the isotropic one and then principal g-values and its direction cosines of the species are obtained by diagonalization of 9 matrix elements of the corresponding g-values. All the paramagnetic defects are identified by the characteristic principal g-values and its direction cosines.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.179-186
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• 2004

A single-dosimeter worn on the anterior surface of body of a worker was found to provide significant underestimation of dose to the worker when radiation comes from behind of the human body. Recently, several researchers suggested that this kind of underestimation can be corrected to a certain extent by using an extra dosimeter on the back. But this multiple dosimetry also has the disadvantages like overestimation lowering work efficiency or cost burden. In this study, a single dosimeter introducing asymmetric filters enabled to identify PA exposure was designed by monte-carlo simulation and experiments and its dose evaluation algorithm for AP-PA mixed radiation field was established. This algorithm was applicable to penetrating radiation which had the effective energy more than 100 keV. Besides, the dosimeter and algorithm in this study were possible to be applied to near PA exposure.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.586-594
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• 2004

This study is the qualitative study in order to discover a direction of field courses by analyzing what elementary school students observe or hypothesis in field courses. The purpose of it is to find any relevancy between the observations and hypotheses generated. The result of the study were as follows; First, most participants have observed mostly based on their vision due to the characteristic of field courses, and the observations of sedimentary layers were mainly generated on the rocks while most hypotheses were on geological structures. Secondly, according to observational descriptions the frequency of the comparative observation was high as well as the cases when two different types of observations were joined together. The last conclusion from this investigation is, according to the standard of observational types, the hypotheses combined with the interpretive observation and comparative observation had the greatest percentage. This shows that many participants tried to rationalize their thoughts by interpreting geological structures and comparing them with other people's cases as well. Scientific explanatory hypotheses were mainly found according to the standard of hypothetical types, which can be constructed that those participants tried to explain and apply established knowledge and preconception.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.431-435
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• 2010

In this paper, we investigated the dependence of device performance and hot carrier lifetime on the channel direction of PMOSFET. $I_{D.sat}$ vs. $I_{Off}$ characteristic of PMOSFET with <100> channel direction is greater than that with <110> channel direction because carrier mobility of <100> channel direction is greater than that of <110> channel direction. However, hot carrier lifetime for <110> channel direction is much lower than that with <110> channel due to the greater impact ionization rate in the <100> channel direction. Therefore, concurrent consideration of reliability characteristics and device performance is necessary for channel strain engineering of MOSFETs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.8
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• pp.107-112
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• 2007

The flux-lock type SFCL consists of transformer with primary and secondary windings connected to a superconducting element in serial. It can be divided into the subtractive and the additive polarity windings according to the winding direction. It could change the fault current limiting characteristics according to the inductance ratio between the coil 1 and coil 2. We investigated the voltage-current characteristics of the flux-lock type SFCL according to the increment of applied voltage. When the applied voltage of the SFCL with the subtractive and the additive polarity windings was increased a initial limiting current ($I_{ini}$) and the quench time of the superconducting element were increased. The recovery time of the superconducting element was increased by increment of applied voltage. Therefore, it was confirmed that recovery characteristics in the flux-lock type SFCL were largely dependent on the consumed energy of a superconducting element because of increment of the consumption power into the superconducting element.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.123-127
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• 1992

When MOS devices is exposed to radiation, radiation effects of P-type MOS capacitor can cause modulation and/or degradation in devices characteristics and its operating life. The oxide layer is grown in $O_2$+T.C.E. and its thickness ranges from 40 to 80 nm. Irradiations on MOS capacitor were performed by Cobalt-60 gamma ray source and total dose ranges from $10^4$ to $10^8$ rads. The radiation effect on electrical conduction characteristics(I-V) in MOS capacitor was measured as a function of gate oxide thickness and total dose. From the experimental result, I-V characteristics is found to be influenced strongly by total dose in irradiated p-type MOS capacitors. The ohmic current is dependant on of total dose in irradiated P-type MOS capacitors. This results are explained using surface states at interface radiation-induced traps.

• Electrical & Electronic Materials
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• v.5 no.3
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• pp.284-294
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• 1992

합성용질확산법으로 GaP단결정을 성장시키고 몇가지 성질을 조사하였다. 정지상태에서 결정의 성장속도는 1.75[mm/day]이었고 결정성장용 석영관을 전기로내에서 하강시키므로써 양질의 GaP 단결정을 성장하였다. 에치피트밀도는 결정의 성장축 방향으로 3.8*$10^{4}$[$cm^{-2}$]부터 2.3*$10^{5}$[$cm^{-2}$] 까지 증가하였다. 성장된 GaP결정의 이동도와 캐리어농도는 실온에서 197.49[$cm^{2}$/V.sec]와 6.75*$10^{15}$[$cm^{-3}$]이었고 77K의 온도에서는 266.91[$cm^{2}$ /V.sec]와 3.13*$10^{14}$[$cm^{-3}$]이었다. 에너지갭의 온도의존성은 실험적으로 $E_{g}$(T)=2.3383-(6.082*$10^{-4}$) $T^{2}$/(373.096+T)[eV]로 구하여졌다. 저온에서 측정된 광루미네센스 스펙트럼은 구속된 여기자의 복사재결합과 재결합 과정에 포논의 참여로 인하여 에너지갭 부근의 복잡한 선 스펙트럼이 나타났고 얕은 준위의 Si도너와 Zn억셉터준위 사이에서의 복사재결합 및 이에 대한 1LO, 2LO의 포논복제가 나타났으며 S $i_{Ga}$ -S $i_{p}$의 쌍방출에 의하여 1.8932[eV]에서 넓은 반치전폭의 피크가 나타났다. GaP의 적외선 흡수는 TO, LO, LA, T $A_{1}$, T $A_{2}$ 포논들의 이중결합모드와 G $a_{2}$O의 진동모드 및 Si도너와 Zn억셉터들에 의하여 일어났다. Zn를 확산시키어 제작한 p-n GaP발광다이오드는 실온에서의 발광중심피크가 6250[.angs.]이었고 최대광출력은 0.0916[mW], 양자효율은 0.51%이었다.이었다.

• Spatial Information Research
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• v.12 no.4 s.31
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• pp.351-370
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• 2004

At present, environmental monitoring of linear infrastructure is based mainly on field sampling. The 'integrated mapping' approach has received only limited attention from field scientists. The increased environmental regulation of corridor targets has required remote sensing research to develop a sensor or technique for targets ranging from 15 m to 100 m in swath width. In an attempt to identify the optimal remote sensing system for linear targets, an overview is provided of the application requirements and the technology currently available. The relative limitation of traditional remote sensing systems in such a linear application is briefly discussed. It is noted that airborne video could provide, in a cost-effective manner, information required for a very narrow and long strip target utilising the narrow view angle and dynamic stereo coverage. The value of this paper is warranted in proposing a new concept of video infrastructure monitoring as a future research direction in the recognition of sensor characteristics and limitations.

• Journal of the Korean Magnetics Society
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• v.16 no.3
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• pp.186-191
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• 2006

Ferromagnetic amorphous $Ni_{16}Fe_{62}Si_8B_{14}$ and $Co_{70.5}Fe_{4.5}Si_{15}B_{10}$ layers have been devised and incorporated as free layers of magnetic tunnel junctions (MTJs) to improve MRAM reading and writing performance. The NiFeSiB and CoFeSiB single-layer film exhibited a lower saturation magnetization ($Ms=800emu/cm^3,\;and\;560emu/cm^3$, respectively) compared to that of a $Co_{90}Fe_{10}(Ms=1400emu/cm^3)$. Because amorphous ferromagnetic materials have lower Ms than crystalline ones, the MTJs incorporating amorphous ferromagnetic materials offer lower switching field ($H_{sw}$) values than that of the traditional CoFe-based MTJ. The double-barrier MTJ with an amorphous NiFeSiB free layer offered smooth surface resulting in low bias voltage dependence, and high $V_h\;and\;V_{bd}$ compared with the values of the traditional CoFe-based MTJ.

• JOURNAL OF ELECTRICAL WORLD
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• s.351
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• pp.89-94
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• 2006

에너지 해외의존도 97%, 무역의존도 70%인대한민국. 우리는하루220만배럴, 연간8억배럴이상을소비한다. 부존자원이 극도로 빈약한 우리나라가 나아가야 할 길은자명하다. 에너지 자원을 거의수입해 의존하다보니 이를고부가화 해 내수에 돌리면서 최우선으로 수출을 통해 온나라가 먹고 살고 있다해도 과언이아니다. 해외 에너지자원을 안정적으로 확보하는 것이 바로 국가경쟁력의 근원이 되는것은 어제오늘의 일이 아니다. 고유가 파고를 헤쳐나가야 한다는 절박한현실에서안정적인 에너지자원확보를 위한 정부의 해외자원분야 정책 및 민관전략이 올들어 의욕적으로 전개되고 있다. 우선정부는 자원개발 업무를 강화하기 위해 현재1과1팀의 자원개발조직을 보강하 고유전개발팀을 신설하는 등 모두3개팀으로 늘린다. 나아가 해외 자원확보에주력 산업 동반진출도 착착진행하고 있다. 국내 자원 개발 기업과 에너지관련기업, 해외진출기관등 14곳으로 구성된 ‘에너지산업해외진출협의회’도 최근 출범시켰다. 유전을탐사하거나 개발하는데 개인들도간접투자할수있는 ‘유전개발펀드’도 7월에 첫 선을 보인다. 약2000억원규모의이 시범펀드 도입 등을 통해 자원개발을 가속화,2013년까지원유-가스자주개발률을18%(원유15%, 가스30%)까지 끌어 올릴 계획이며 여기에16조원 신규투자가 소요 될 것으로보고있다. 이같은 일련의 공격적인 움직임은 단순히 돈을 주고 자원을 사오는 기존방식을 앞으로는과감히탈피,자원부국이 원하는 산업인프라등을 수주해제 공한뒤 그 대가로자원을 확보하는 총체적 자원확보전략에 무게를두겠다는 의지를 담고 있어 고무적이다. 여기에 다원유 등 수입원자재 가격이 급등세를 보이고있는 가운데 우리나라의 해외 자원개발사업이 활기를 띠고있다.석유공사는 민간기업들과 함께 지난해에만 예멘2곳 등 전세계 5개국9곳의 석유 및 천연가스 광구계약을체결, 올들어 최근참여사들과 함께 주주간계약 서명식을 갖고본격적인 사업을 추진 중이다. 광업진흥공사역시 SK네트웍스와제휴, 최근 전체 매장량이650만t으로 추정되는 중국 후난성의 아연광 탐사권을 획득, 합작 사설립계약을 체결한 것으로 알려지고 있다. 민간기업들도 해외자원분야진출이 활발하다. 기업들의 해외 자원개발을 위한 투자규모도 늘어 올해38개 해외 자원개발기업이 32개국 211개 사업에 모두31억달러를 투자할 계획인것으로 나타났다. 이에본지는 올해 들어서도 고유가의 지속으로 속증하고 있는에너지수입동향과 해외 자원 개발의 현실과 문제점, 개선방향, 나아가 최근 안전적인 자원확보를 위한 동향을 진단해본다.