• 한국재료학회지
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• 제7권8호
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• pp.707-713
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• 1997

HVPE(hydride vapor phase epitaxy)법으로 (111)MgAI$_{2}$ $O_{4}$기판위에 GaN 후막을 성장하였다. GaN를 성장하기 전에 기판에 표면을 GaCI로 처리한 수 성장하였을 때 이중 X선 회절 피크의 반치폭이 710 arcsec로서 N $H_{3}$로 처리한 후 성장한 GaN에 비하여 작았으며, 무색 투명의 경면상태가 얻어\ulcorner다. 113$0^{\circ}C$의 온도에서 성장한 GaN 의 광루미네센스(PL)특성과 동일하게 나타났다. 10K의 온도에서 측정된 PL 스펙트럼은 자유여기자와 속박여기자의 재결합천이에 의한 피크들과 Mg과 관련된 도너-억셉터 쌍 사이의 재결합 및 이의 1LO, 2LO, 3LO 및 4 LO 포논복제에 의한 피크들이 나타났다. 성장된 GaN는 n형의 전도성을나타내었으며, 캐리어 이동도와 농도는 각각 21.3$\textrm{cm}^2$/V ㆍsec와 4.2 x $10^{18}$$cm^{-3}$이었다.

• 한국ITS학회 논문지
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• 제2권2호
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• pp.97-101
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• 2003

본 논문에서는 Ku-band용 주파수 하향변환기에 사용할 수 있는 MMIC (monolithic microwave integrated circuit) mixer를 InGaAs/GaAs p-HEMT 공정의 Schottky diode를 이용하여 설계 및 제작하였다. 일반적인 double balanced mixer의 구조에서 IF단자와 LO 단자를 서로 바꾸어 설계함으로써 mC chip의 크기를 크게 줄일 수 있었다. 설계된 MMIC mixer는 RF(14.0 - 14.5 GHz)와 IF(12.252 - 12.752 GHz)의 주파수 대역에서 사용할 수 있다. 제작된 초소형의 MMIC mixer chip은 크기가 3.3 m X 3.0 m이고, on-wafer측정 결과 9.8 dB 이하의 변환손실과 23 dB 이상의 RF-to-IF 격리도 및 38 dB 이상의 LO-to-IF 격리도의 특성을 각각 얻었다.

• 한국초전도ㆍ저온공학회논문지
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• 제17권4호
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• pp.16-20
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• 2015

We investigated optical properties of an electron-doped copper oxide high temperature superconductor, $Pr_{0.85}LaCe_{0.15}CuO_4$ (PLCCO) single crystal. We obtained the optical conductivity from measured reflectance at various temperatures. We found our data contained c-axis longitudinal optical (LO) phonon modes due to miscut and intrinsic lattice distortion. We applied an extended Drude model to study the correlations between charge carriers in the system. The LO phonons appear as strong sharp peaks in the optical scattering rate. We tried to remove the LO phonon modes by using the energy loss function, which also shows the LO phonons as peaks, and could not remove them completely. We extracted the electron-boson spectral density function using a generalized Allen's formula. We observed that the resulting electron-boson density show similar temperature dependence as hole-doped cuprates.

• 한국통신학회논문지
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• 제31권2C호
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• pp.109-116
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• 2006

초광대역(UWB) 통신시스템의 응용 시나리오는 많은 경우 비가시적(non-LoS) 환경에서의 응용을 가정하고 있다. UWB 신호가 매질을 투과하여 방사될 경우 신호의 왜곡현상이 발생하며, 이는 수신부 상관기의 기준신호와 수신된 신호와의 상관계수를 감소시켜 성능을 저하시키는 요인이 된다. 본 논문에서는 가설검증 방식을 이용한 UWB Rake 수신기의 기준신호 선택 기법을 소개한다. 가설을 세우기 위한 파형의 선택을 위해 벡터 양자화 기법인 Linde-Buzo-Gray(LBG) 알고리듬을 사용하였다. 개시된 알고리듬을 성능을 non-LoS 환경에서 측정된 데이터를 이용해 평가하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2016년도 추계학술발표대회
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• pp.816-818
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• 2016

LPWA 기술은 IoT 환경이 가지는 낮은 전송거리와 배터리 제약을 해결할 수 있는 통신규약이다. LPWA에서 주목 받는 LoRa 기술은 디바이스에서 전송방식을 선택할 수 있는 클래스 A, B, C를 제공한다. 이 논문은 클래스 B 옵션에서 동기는 맞으나 전송 중 Beacon메시지를 분실하였을 경우, 바로 실행되던 Beacon-less동작을 억제하도록 최대 실패 횟수를 설정한다. 기존방법보다 Beacon-less동작이 기존 방법에 비해 30배 이상 적게 동작하여 디바이스의 에너지 소모를 줄였다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권1호
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• pp.377-381
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• 2012

The aim of this study was to screen for polypeptides binding specifically to LoVo human colorectal cancer cells using a phage-displayed peptide library as a targeting vector for colorectal cancer therapy. Human normal colorectal mucous epithelial cells were applied as absorber cells for subtraction biopanning with a c7c phage display peptide library. Positive phage clones were identified by enzyme-linked immunosorbent assay and immunofluorescence detection; amino acid sequences were deduced by DNA sequencing. After 3 rounds of screening, 5 of 20 phage clones screened positive, showing specific binding to LoVo cells and a conserved RPM motif. Specific peptides against colorectal cancer cells could be obtained from a phage display peptide library and may be used as potential vectors for targeting therapy for colorectal cancer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.536-543
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• 2003

In this paper, we describe a unique self oscillating and mixing (SOM) down-converter design using a modified defected ground structure (DGS). The proposed SOM converter is consisted of self-oscillator, which can produce negative resistance and select resonance frequency, RF matching circuit, and IF low pass filter. As the advantage of this SOM converter can mix LO and RF signals as well as inducing LO signal with only one active device. it is designed as a simple structure and the low cost. Also, there is easy advantage to be applied in RFIC/MMIC technology because it offers excellent phase noise performance in spite of using micro-strip structure. The LO signal for the proposed SOM converter is designed at 1㎓ and RF frequency was chosen to be 800MHz. The achieved conversion loss and phase noise performances of the implemented SOM converter are 15㏈ and -95dBc/Hz at 100KHz offset frequency respectively. The equivalent circuit parameters for DGS are extracted by using a three dimensional EM simulator and simple circuit analysis method.

• Asian-Australasian Journal of Animal Sciences
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• 제22권5호
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• pp.659-666
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• 2009

Metabolizable protein (MP) supply and amino acid balance in the intestine were manipulated through selection of highly digestible rumen-undegradable protein (RUP) sources and protected methionine (Met) supplementation. Four ruminallycannulated, multiparous Holstein cows averaging 193${\pm}$13 days in milk were used in a 4${\times}$4 Latin square design to assess N utilization and milk production responses to changes in RUP level, post-ruminal RUP digestibility and protected Met supplementation. Treatments were A) 14.0% crude protein (CP), 8.0% rumen degradable protein (RDP) and 6.0% RUP of low intestinal digestibility (HiRUP-LoDRUP); B) 14.1% CP, 8.1% RDP and 6.0% RUP of high intestinal digestibility (HiRUP-HiDRUP); C) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility (LoRUP-HiDRUP), and D) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility plus rumen escape sources of Met (LoRUP-HiDRUP+Met). Experimental diets were formulated to have similar concentrations of RDP, net energy of lactation ($NE_L$), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium, phosphorus and ether extract using the NRC model (2001). Results showed that dry matter intake (DMI), production of milk fat and protein were similar among treatments. Milk production was similar for diet HiRUP-LoDRUP, HiRUP-HiDRUP and LoRUP-HiDRUP+Met, and significantly higher than diet LoRUP-HiDRUP. Milk fat and protein percentage were higher for cows receiving HiDRUP treatments, with the greatest increases in the diet LoRUP-HiDRUP+Met. There was no significant change in ruminal pH, $NH_3g-N$ and volatile fatty acid (VFA) concentration among all treatments. Apparent digestibility of dry matter (DM), CP, NDF and ADF and estimated bacterial CP synthesis were similar for all treatments. Nitrogen intakes, blood and milk urea-N concentrations were significantly higher for cows receiving HiRUP diets. Urine volume and total urinary N excretion were significantly lowered by LoRUP diets. Lowering dietary RUP level while supplementing the highly digestible RUP source with rumen escape sources of Met resulted in similar milk production, maximal milk fat and protein concentration and maximum N efficiency, indicating that post-ruminal digestibility of RUP and amino acid balance in the small intestine can be more important than total RUP supplementation.

• Radiation Oncology Journal
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• 제35권3호
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• pp.281-288
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• 2017

Purpose: The serum carcinoembryonic antigen (CEA) level has been recognized as a prognostic factor in colorectal cancer, and associated with response of rectal cancer to radiotherapy. This study aimed to identify CEA-interacting proteins in colon cancer cells and observe post-irradiation changes in their expression. Materials and Methods: CEA expression in colon cancer cells was examined by Western blot analysis. Using an anti-CEA antibody or IgG as a negative control, immunoprecipitation was performed in colon cancer cell lysates. CEA and IgG immunoprecipitates were used for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Proteins identified in the CEA immunoprecipitates but not in the IgG immunoprecipitates were selected as CEA-interacting proteins. After radiation treatment, changes in expression of CEA-interacting proteins were monitored by Western blot analysis. Results: CEA expression was higher in SNU-81 cells compared with LoVo cells. The membrane localization of CEA limited the immunoprecipitation results and thus the number of CEA-interacting proteins identified. Only the Ras-related protein Rab-6B and lysozyme C were identified as CEA-interacting proteins in LoVo and SNU-81 cells, respectively. Lysozyme C was detected only in SNU-81, and CEA expression was differently regulated in two cell lines; it was down-regulated in LoVo but up-regulated in SNU-81 in radiation dosage-dependent manner. Conclusion: CEA-mediated radiation response appears to vary, depending on the characteristics of individual cancer cells. The lysozyme C and Rab subfamily proteins may play a role in the link between CEA and tumor response to radiation, although further studies are needed to clarify functional roles of the identified proteins.

• BMB Reports
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• 제52권7호
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• pp.445-450
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• 2019

TTYH2 is a calcium-activated, inwardly rectifying anion channel that has been shown to be related to renal cancer and colon cancer. Based on the topological prediction, TTYH2 protein has five transmembrane domains with the extracellular N-terminus and the cytoplasmic C-terminus. In the present study, we identified a vesicle transport protein, ${\beta}$-COP, as a novel specific binding partner of TTYH2 by yeast two-hybrid screening using a human brain cDNA library with the C-terminal region of TTYH2 (TTYH2-C) as a bait. Using in vitro and in vivo binding assays, we confirmed the protein-protein interactions between TTYH2 and ${\beta}$-COP. We also found that the surface expression and activity of TTYH2 were decreased by co-expression with ${\beta}$-COP in the heterologous expression system. In addition, ${\beta}$-COP associated with TTYH2 in a native condition at a human colon cancer cell line, LoVo cells. The over-expression of ${\beta}$-COP in the LoVo cells led to a dramatic decrease in the surface expression and activity of endogenous TTYH2. Collectively, these data suggested that ${\beta}$-COP plays a critical role in the trafficking of the TTYH2 channel to the plasma membrane.