• 한국지반공학회논문집
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• 제34권2호
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• pp.55-63
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• 2018

열차의 하중을 적절한 강성으로 지지하기 위하여 다짐시공된 노반의 효과적인 강성특성 평가 기법에 대한 연구가 요구된다. 본 연구에서는 상부노반에 대하여 크로스홀 형태의 동적 콘 관입기(CDCP)를 적용함으로써 심도에 따른 강성특성을 평가하고자 하였다. CDCP의 적용을 위하여 세 단면의 다짐시공 완료된 상부노반이 대상 현장으로 선택되었으며, 각각의 개소에 대하여 CDCP 관입실험 및 들밀도시험, 동평판재하시험(LFWD)이 수행되었다. CDCP 관입실험 결과, 심도에 따른 탄성파 발신시간 및 전단파 수신시간을 획득하였으며, 이를 이용하여 노반의 전단파속도 주상도를 획득하였다. 또한, 동일 개소에서 들밀도시험으로부터 획득한 노반의 밀도 및 전단파속도 주상도를 이용하여 심도에 따른 최대전단강성계수($G_{max}$)를 평가할 수 있었다. CDCP 관입실험 및 들밀도시험으로부터 평가된 최대전단강성계수와 LFWD시험으로부터 획득한 동탄성계수($E_{vd}$)를 상호비교한 결과 매우 우수한 선형관계를 보이므로, CDCP 관입실험으로부터 유효한 강성특성을 평가할 수 있을 것이라 판단되었다. 또한, CDCP 관입실험으로부터 도출되는 결과는 일정 심도에 대한 대표 강성특성이 아닌 심도에 따른 연속적인 강성특성 이므로 노반의 강성특성 평가에 효과적으로 이용될 수 있을 것이라 기대된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.284-284
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• 2016

Topological insulator (TI) is a bulk-insulating material with topologically protected Dirac surface states in the band gap. In particular, $Bi_2Se_3$ attracted great attention as a model three-dimensional TI due to its simple electronic structure of the surface states in a relatively large band gap (~0.3 eV). However, experimental efforts using $Bi_2Se_3$ have been difficult due to the abundance of structural defects, which frequently results in the bulk conduction being dominant over the surface conduction in transport due to the bulk doping effects of the defect sites. One promising approach in avoiding this problem is to reduce the structural defects by heteroepitaxially grow $Bi_2Se_3$ on a substrate with a compatible lattice structure, while also preventing surface degradation by encapsulating the pristine interface between $Bi_2Se_3$ and the substrate in a clean growth environment. A particularly promising choice of substrate for the heteroepitaxial growth is hexagonal boron nitride (h-BN), which has the same two-dimensional (2D) van der Waals (vdW) layered structure and hexagonal lattice symmetry as $Bi_2Se_3$. Moreover, since h-BN is a dielectric insulator with a large bandgap energy of 5.97 eV and chemically inert surfaces, it is well suited as a substrate for high mobility electronic transport studies of vdW material systems. Here we report the heteroepitaxial growth and characterization of high quality topological insulator $Bi_2Se_3$ thin films prepared on h-BN layers. Especially, we used molecular beam epitaxy to achieve high quality TI thin films with extremely low defect concentrations and an ideal interface between the films and substrates. To optimize the morphology and microstructural quality of the films, a two-step growth was performed on h-BN layers transferred on transmission electron microscopy (TEM) compatible substrates. The resulting $Bi_2Se_3$ thin films were highly crystalline with atomically smooth terraces over a large area, and the $Bi_2Se_3$ and h-BN exhibited a clear heteroepitaxial relationship with an atomically abrupt and clean interface, as examined by high-resolution TEM. Magnetotransport characterizations revealed that this interface supports a high quality topological surface state devoid of bulk contribution, as evidenced by Hall, Shubnikov-de Haas, and weak anti-localization measurements. We believe that the experimental scheme demonstrated in this talk can serve as a promising method for the preparation of high quality TI thin films as well as many other heterostructures based on 2D vdW layered materials.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.281.2-281.2
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• 2016

Two-dimensional van der Waals (2D vdWs) materials have been extensively studied for future electronics and materials sciences due to their unique properties. Among them, black phosphorous (BP) has shown infinite potential for various device applications because of its high mobility and direct narrow band gap (~0.3 eV). In this work, we demonstrate a few-nm thick BP-based nonvolatile memory devices with an well-known poly(vinylidenefluoride-trifluoroethylene) [P(VDF-TrFE)] ferroelectric polymer gate insulator. Our BP ferroelectric memory devices show the highest linear mobility value of $1159cm^2/Vs$ with a $10^3$ on/off current ratio in our knowledge. Moreover, we successfully fabricate the ferroelectric complementary metal-oxide-semiconductor (CMOS) memory inverter circuits, combined with an n-type $MoS_2$ nanosheet transistor. Our memory CMOS inverter circuits show clear memory properties with a high output voltage memory efficiency of 95%. We thus conclude that the results of our ferroelectric memory devices exhibit promising perspectives for the future of 2D nanoelectronics and material science. More and advanced details will be discussed in the meeting.

• 한국정보통신학회논문지
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• 제6권7호
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• pp.1074-1078
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• 2002

본 논문에서는 main gate(MG)와 side gate(SG)를 갖는 double gate(DG) MOSFET를 디자인하고 TCAD를 이용하여 시뮬레이션하였다. MG와 SG의 길이(LMG, LSG)는 각각 50nm, 70nm로 하였으며, MG와 SG의 전압(VMG, VSG)이 각각 1.5V, 3.0V일 때 드레인전압(VD)을 0에서 1.5V까지 변화시키면서 핀치오프특성을 조사하였다. LMG가 아주 작음에도 불구하고, 핀치-오프특성이 아주 좋게 나타났다. 이것은 DG MOSFET의 VMG가 게이트를 제어하는 역할을 잘 수행하여 나노 구조에서 유용한 구조임을 알 수 있었다.

• Archives of Pharmacal Research
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• 제18권4호
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• pp.237-242
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• 1995

For the vioequivalence study of two ceftriaxone injection formulations ($Rocephin{\circledR}$ ; Roche, and Triaxone ; Hanmi0, the HPLC analytical method for the analysis of ceftriaxone in plasma was used. Fourteen healthy volunteers completed the study and each subject were IM in jected signle doses (1 g) of the test and the reference formulations in a two-way crossover design with an one week drug free interval between doses. Following each administration, plasma concentrations of ceftrixone were monitored over a period of 24 h. Bioequivalence parameters $AUC_{24th}, {\;}T_{max}, {\;}C_{max}$ and MRT determined from the data obtained for the two formulations were examined by analyses of variance (ANOVA) and other criteria and tests for bioequivalence. Results of ANOVA and confidence limits of test/reference ratios of $AUC_{24th}, {\;}T_{max}, {\;}C_{max}$ and MRT, and statistical tests indicated the bioequivalence of the two formulations (i.e., test/reference ratio was within $100{\pm}20%$) except for $T_{max}$ The mean of $T_{max}$ showed only 6. 9% difference from the reference but the detection limit was 22.5% which is slightly over the 20% criteria. No pharmacokinetic parameters including Ka, Kel, Vd and Cl indicated significant difference in between the two fomulations. It was concluded that the data yielded fro the two cefriaxone formulations demonstrated that they were bioequivalent.

• 음성과학
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• 제13권3호
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• pp.49-65
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• 2006

Recently, several theories on the digital speech signal processing expanded the communication boundary between human beings and machines drastically. The aim of this study is to collect dialectal speech in Korea on a large scale and to establish a digital speech data base in order to provide the data base for further research on the Korean dialectal and the creation of value-added network. 528 informants across the country participated in this study. Acoustic characteristics of vowels and consonants are analyzed by Power spectrum and Spectrogram of CSL. Test words were made on the picture cards and letter cards which contained each vowel and each consonant in the initial position of words. Plot formants were depicted on a vowel chart and transitions of diphthongs were compared according to dialectal speech. Spectral times, VOT, VD, and TD were measured on a Spectrogram for stop consonants, and fricative frequency, intensity, and lateral formants (LF1, LF2, LF3) for fricative consonants. Nasal formants (NF1, NF2, NF3) were analyzed for different nasalities of nasal consonants. The acoustic characteristics of dialectal speech showed that young generation speakers did not show distinction between close-mid /e/ and open-mid$/\epsilon/$. The diphthongs /we/ and /wj/ showed simple vowels or diphthongs depending to dialect speech. The sibilant sound /s/ showed the aspiration preceded to fricative noise. Lateral /l/ realized variant /r/ in Kyungsang dialectal speech. The duration of nasal consonants in Chungchong dialectal speech were the longest among the dialects.

• Journal of Pharmaceutical Investigation
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• 제30권2호
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• pp.113-118
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• 2000

In order to assay the efficacy of newly synthesized antiviral compounds, pyrimidine analogs, pharmacokinetics of those were established as compared with already marketed zidovudine. Zidovudine (15, 20, 25 and 35 mg/kg), LJ142 (18.52 mg/kg) and LJ143 (15, 18.52 and 30 mg/kg) were administered orally and intravenously in rats, blood samples were collected post-injection(i.e., for 360 min) at appropriate time intervals. Those were analyzed by HPLC with UV detection at 265 nm. Pharmacokinetic parameters $(C_{max},\;T_{1/2},\;MRT,\;AUC,\;AUMC,\;Vd_{SS},\;Cl_t)$ were calculated. AUCs of zidovudine and LJ143 following I.V. dosing of $15{\sim}25\;mg/kg\;and\;15{\sim}18.18\;mg/kg$ were dose-independent. However, AUCs of zidovudine and LJ43 following I.V. dosing of $25{\sim}35\;mg/kg\;and\;18.18{\sim}30\;mg/kg$ were dose-dependent. The relative bioavailability of zidovudine, LJ142 and LJ143 following oral administration were 61.94, 46.44 and 78.24%, respectively.

• 한국축산식품학회지
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• 제42권5호
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• pp.861-873
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• 2022

The drying of duck blood provides safety and commercial benefits, but each drying method has its own characteristics. Moreover, information on the effects of diverse drying methods on the quality of duck blood is limited. This study aimed to investigate the effects of various drying methods on the chemical and functional properties of duck blood. The physicochemical characteristics and functional properties of duck blood subjected to spray drying (SD), freeze drying (FD), vacuum drying (VD), and hot air drying (HD) were examined. The carbonyl content of FD duck blood powder was the lowest and the thermal stability was higher than that of the other treatments (p<0.05). The gel obtained from spray-dried blood displayed the lowest malondialdehyde content. The hardness, gumminess, and chewiness were the highest in the heat-induced gel prepared from FD duck blood powder (p<0.05). The gel obtained from FD duck blood displayed a denser structure than the other gel samples. Taken together, the FD duck blood exhibited excellent chemical properties and processing suitability.

• 한국임상약학회지
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• 제12권2호
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• pp.71-75
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• 2002

This study was carried out to compare the bioavailability of $Ceclex^{(R)}$ (test drug, cefaclor 250 mg/capsule) with that of $Ceclor^{(R)}$ (reference drug) and to estimate the pharmacokinetic parameters of cefaclor in healthy Korean adult. The bioavailability was examined on 20 healthy volunteers who received a single dose (250 mg) of each drug in the fasting state in a randomized balanced 2-way crossover design. After dosing, blood samples were collected for a period of 6hours. Plasma concentrations of cefaclor were determined using HPLC with UV detection. The pharmacokinetic parameters $(AUC_{0-6hr},\;C_{max},\;T_{max},\;AUC_{int},\;K_e,\;t_{1/2},\;Vd)$ F, and CL/F) were calculated with non-compartmental pharmacokinetic analysis. The ANOVA test was utilized for the statistical analysis of the $T_{max},\;log-transformed\;AUC_{0-6hr}\;log-transformed\;C_{max},\;t_{l/2},\;V_d/F$, and CL/F. The ratios of geometric means of AUC0-6hr and $C_{max}$ between test drug and reference drug were $103.2\%\;(6.74\;{\mu}g{\cdot}hr/ml\;vs\;6.53{\pm}g{\cdot}hr/ml)\;and\;100.4\%\;(4.85\;{\mu}g\ml\;vs\;4.82\;{\mu}g/ml)$, respectively. The $T_{max}$ of test drug and reference drug were $0.9\pm0.38\;hr\;and\;0.83\pm0.34$ hrs, respectively. The $90\%$ confidence intervals of mean difference of logarithmic transformed $AUC_{0-6h},\;and\;C_{max}$ were log $0.98{\sim}log$ 1.08 and log $0.88{\sim}log1.15$, respectively. It shows that the bioavailability of test drug is equivalent with that of reference drug. The estimated half-life of this study was longer $(1.21\pm0.27\;hrs\;vs\;0.5-1\;hr)$, the Vd/F was larger $(68.89\pm25.72L$ vs 24.9L), and the CL/F was higher $(38.62\pm7.09\;L/hr$ vs 24.9 L/hr) than the previously reported values.

• 한국안광학회지
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• 제3권1호
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• pp.189-199
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• 1998

완성안경의 광학적 허용요차에 대한 system을 안경처방서 작성시 환경, 주시거리, 하방 주시각, 테의 늘어남, 정정간 거리(VD), 토릭렌즈의 축, 렌즈의 기울기 등의 누적 오차 합 형태로 만들었다. 굴절력(D)에 따른 $O{\cdot}C$의 허용치 크기(T) 관계를 $T=T_0e^{-aD}$으로 주어지고 여기서, $T_0$는 굴절력이 0인 평면렌즈의 허용치 크기이고, ${\alpha}$는 허용치 factor이다. RAL-915에 대응하는 새로운 형태의 허용오차를 적용하는 경우, 허용오차가 큰 방향에 대해서는 허용치 factor ${\alpha}$는 $0.166(T_0=5.90)$이고, 허용오차가 작은 방향에 대해서는 허용치 factor ${\alpha}$는 $0.166(T_0=2.95)$ 값을 갖는다.