• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4431-4446
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• 2023

A Multiphysics coupling framework, MPCORE, has been developed to analyze safety parameters using the best estimate codes. The framework contains neutron kinetics (NK), thermal hydraulics (TH), and fuel performance (FP) codes to analyze fuel burnup, radial power distribution, and coolant temperature (T_bc). Shuffling and rotation capabilities have been verified on the Watts Bar reactor for three cycles. This study focuses on two coupling approaches for TH and FP modules. The one-way coupling approach involves coupling the FP code with the NK code, providing no data to the TH modules but getting T_bc as boundary condition from TH module. The two-way coupling approach exchanges information from FP to TH modules, so that the simplified heat conduction solver of the TH module is not used. The power profile in both approaches does not differ significantly, but there is an impact on coolant and cladding parameters. The one-way coupling approach tends to over-predict the cladding hydrogen concentration (CHC). This research highlights the difference between one-way and two-way coupling on critical boron concentration, T_bc, CHC, oxide surface temperature, and pellet centerline temperature. Overall, MPCORE framework with two-way coupling provides a more accurate and reliable analysis of safety parameters for nuclear reactors.

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.462-467
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• 2009

The Charge Trap Flash (CTF) memory device is a replacement candidate for the NAND Flash device. In this study, Pt/$Al_2O_3/La_2O_3/SiO_2$/Si multilayer structures with lanthanum oxide charge trap layers were fabricated for nonvolatile memory device applications. Aluminum oxide films were used as blocking oxides for low power consumption in program/erase operations and reduced charge transports through blocking oxide layers. The thicknesses of $SiO_2$ were from 30 $\AA$ to 50 $\AA$. From the C-V measurement, the largest memory window of 1.3V was obtained in the 40 $\AA$ tunnel oxide specimen, and the 50 $\AA$ tunnel oxide specimen showed the smallest memory window. In the cycling test for reliability, the 30 $\AA$ tunnel oxide sample showed an abrupt memory window reduction due to a high electric field of 9$\sim$10MV/cm through the tunnel oxide while the other samples showed less than a 10% loss of memory window for $10^4$ cycles of program/erase operation. The I-V measurement data of the capacitor structures indicated leakage current values in the order of $10^{-4}A/cm^2$ at 1V. These values are small enough to be used in nonvolatile memory devices, and the sample with tunnel oxide formed at $850^{\circ}C$ showed superior memory characteristics compared to the sample with $750^{\circ}C$ tunnel oxide due to higher concentration of trap sites at the interface region originating from the rough interface.

• The Inventors News
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• no.51
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• pp.1-16
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• 2006

함께 즐기는 '여성 발명인 축제'열린다/이 가을을 여성 발명의 계절로/빠진 영구치, 임플란트 기술로 대신한다/국내 의약품 특허출원 외국 기업이 주도/웰빙 붐 타고 기능성 베개 출원 늘어나/토양오염 복원기술, 관심 높아져/기업 CI교체 따른 상표출원 급증/여성경제단체, 오세훈 서울 시장 초청 간담회 가져/'2006대한민국 발명특허대전' 개최/특허청, 중소기업 특허경영 지원단 발족/한국특허문헌, WIPO로 전세계 서비스 실시/APEC 여성지도자네트워크 회의 개최/'2006 특허기술 사업화 성공사례발표회'/세계최초 신개념 CTF기술 상용화/특허청, 제4회 발명 장학생 선발/김치, 러시아 모스크바에 진출한다/고속 주행 틸팅열차 특허로 인정/현직 공무원, 다양한 발명품으로 특허와 되다/자신만의 'TV채널' 선택 가능하다/전지산업, 이온성 액체 관련 특허로 안전하게/명확한 의견 제출로 효율적인 심판 진행/치매예방물질 2배인 김치 개발됐다/한국과학기술연구원 논문 특허심의제도 도입/'한국 오시면 KISS로 맞이합니다'/삼성전자, 중국 특허 마쓰시타 아성 깨다/싱가포르 수출 인큐베이터로 중소기업 해외시장 공략/특허청, 영남대와 지식재산역량 강화 위한 약정 체결/깎는 횟수 줄인 잔디, 세계최초 개발/순창군, 웰빙 고추장 특허출원/역사 속의 발명품/하루 10분 발명교실/특허Q&A/케이제이알텍(주)문승자 대표/한.일 변리사회 업무협정체결 25주년 기념식 개최/중소기업청, 하반기 18조원 신용보증 공급 계획/'2006 대만 국제발명품 전시회'서 한국 참가자 수상/'불났을 때' 긴급 대피 요령은?/아이디어 착상 및 발명 기법/창의성과 도전정신이 성공한 사업가 만든다/사탕을 탄생시킨 사람들/'휴대폰 특허료 1.3억불 내라' 중재 결정/'신발깔창 휴대폰 충전기'/휴대폰으로 광고 받고 무료 문자 이용 가능/아파트 저작권.특허 열풍 거세게 불어/'골다공증 예방 요구르트' 나왔다/갈증 느끼지 않아도 '물' 자주 마셔라/10월 '지재권 및 여성발명 창의교실' 개최안내/한국여성발명협회 회원사 발명품 가이드/함씨네토종콩종합식품, 특선 수상/

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.789-790
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• 2013

$Er_2O_3/SiO_2$ double-layer gate dielectric shows low gate leakage current and high capacitance. In this paper, we apply $Er_2O_3/SiO_2$ double-layer gate dielectric as a charge trap layer for the first time. $Er_2O_3/SiO_2$ double-layer thickness is optimized by EDISON Nanophysics simulation tools. Using the simulation results, we fabricated Schottky-barrier silicide source/drain transistor, which has10 um/10um gate length and width, respectively. The nonvolatile device demonstrated very promising characterstics with P/E voltage of 11 V/-11 V, P/E speed of 50 ms/500 ms, data retention of ten years, and endurance of $10^4$ P/E cycles.

• Journal of Life Science
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• v.19 no.6
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• pp.705-710
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• 2009

Sodium butyrate (NaBt), a naturally occurring short chain fatty acid derived from carbohydrate metabolism in the gut, is known to exhibit strong anti-cancer potentials in various human cancer cells; however, its action mechanism is poorly understood. In the present study, we demonstrated that NaBt up-regulates levels of E-cadherin, a key cell adhesion molecule implicated as a tumor suppressor, in a cell type-specific manner. Although levels of p21, a potential activator for E-cadherin expression, were also up-regulated by treatment with NaBt in several types of cells, it does not seem to be associated with the activation of E-cadherin in the NaBt-treated cells. Instead, the data from promoter analysis suggest that NaBt up-regulates expression of E-cadherin at the transcription level by enhancing its promoter strength via a CCAAT-box. The elevated E-cadherin in the presence of NaBt was primarily localized at the cell-cell contacts, converting Hep3B cells into a more differentiated form.

• BMB Reports
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• v.33 no.6
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• pp.519-524
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• 2000

NF1 proteins are a family of DNA binding proteins which consist of two separate domains, N-terminal DNA binding domain and C-terminal transcription activation domain. The N-terminal 220 amino acids are highly conserved and are also known to mediate dimerization of NF1 proteins. The C-terminal regions of different type of NF1 proteins are heterogeneous and responsible for transcriptional activation. In this study, we tested the interaction between different domains of rat NF1-A protein by yeast two hybrid analysis and observed the interaction between C-terminal regions of NF1-A which do not contain the N-terminal dimerization domain. Our results showed that the C-terminal region of rat NF1-A between residues 231 and 509 strongly interacted not only with itself, but also with human NF1/CTF1 which is a different type of NF1. When the C-terminal region was divided into two fragments, one from residue 231 to 447 and the other from 448 to 509, the two fragments were able to interact with the C-terminal region of NF1-A significantly. This indicates that both fragments contain independent interaction domains. Analysis of the interactions with alanine substituted fragments showed that substitutions of the heptasequence, SPTSPTY of NF1-A, affected interaction between NF1 proteins. Our results strongly suggest that C-terminal regions may also be important for the formation of homo- and heterodimers in addition to the N-terminal dimerization domain. Also, the heptasequence motif may play some roles in dimer formation.

• International Journal of Computer Science & Network Security
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• v.23 no.9
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• pp.8-16
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• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.1-8
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• 2023

An Orthogonal Frequency Division Multiplexing (OFDM) based wireless communication system has drawn wide attention for its high transmission rate and high spectrum efficiency in not only radio but also Underwater Acoustic (UWA) applications. Because of the narrow sub-carrier spacing of OFDM, orthogonality between sub-carriers is easily affected by Doppler effect caused by the movement of transmitter or receiver. Previously, Doppler compensation signal processing algorithm for Desired propagation path was proposed. However, other Doppler shifts caused by delayed Undesired signal arriving from different directions cannot be perfectly compensated. Then Receiver Bit Error Rate (BER) is degraded by Inter-Carrier-Interference (ICI) caused in the case of Multi-path Doppler channel. To mitigate the ICI effect, a modified Delay and Doppler Profiler (mDDP), which estimates not only attenuation, relative delay and Doppler shift but also sampling clock shift of each multi-path component, is proposed. Based on the outputs of mDDP, an ICI canceling multi-tap equalizer is also proposed. Computer simulated performances of one-tap equalizer with the conventional Time domain linear interpolated Channel Transfer Function (CTF) estimator, multi-tap equalizer based on mDDP are compared. According to the simulation results, BER improvement has been observed. Especially, in the condition of 16QAM modulation, transmitting vessel speed of 6m/s, two-path multipath channel with direct path and ocean surface reflection path; more than one order of magnitude BER reduction has been observed at CNR=30dB.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.264-264
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• 2016

최근에 charge trap flash (CTF) 기술은 절연막에 전하를 트랩과 디트랩 시킬 때 인접한 셀 간의 간섭현상을 최소화하여 오동작을 줄일 수 있으며 낸드 플래시 메모리 소자에 적용되고 있다. 낸드 플래시 메모리는 고집적화, 대용량화와 비휘발성 등의 장점으로 인해 핸드폰, USB, MP3와 컴퓨터 등에 이용되고 있다. 기존의 실리콘 기반의 플래시 메모리 소자는 좁은 밴드갭으로 인해 투명하지 않고 고온에서의 공정이 요구되는 문제점이 있다. 따라서, 이러한 문제점을 개선하기 위해 실리콘의 대체 물질로 산화물 반도체 기반의 플래시 메모리 소자들이 연구되고 있다. 산화물 반도체 기반의 플래시 메모리 소자는 넓은 밴드갭으로 인한 투명성을 가지고 있으며 저온에서 공정이 가능하여 투명하고 유연한 기판에 적용이 가능하다. 다양한 산화물 반도체 중에서 비정질 In-Ga-Zn-O (a-IGZO)는 비정질임에도 불구하고 우수한 전기적인 특성과 화학적 안정성을 갖기 때문에 많은 관심을 받고 있다. 플래시 메모리의 고집적화가 요구되면서 절연막에 high-k 물질을 atomic layer deposition (ALD) 방법으로 적용하고 있다. ALD 방법을 이용하면 우수한 계면 흡착력과 균일도를 가지는 박막을 정확한 두께로 형성할 수 있는 장점이 있다. 또한, high-k 물질을 절연막에 적용하면 높은 유전율로 인해 equivalent oxide thickness (EOT)를 줄일 수 있다. 특히, HfOx와 AlOx가 각각 trap layer와 blocking layer로 적용되면 program/erase 동작 속도를 증가시킬 수 있으며 넓은 밴드갭으로 인해 전하손실을 크게 줄일 수 있다. 따라서 본 연구에서는 ALD 방법으로 AlOx와 HfOx를 게이트 절연막으로 적용한 a-IGZO 기반의 thin-film transistor (TFT) 플래시 메모리 소자를 제작하여 메모리 특성을 평가하였다. 제작 방법으로는, p-Si 기판 위에 열성장을 통한 100 nm 두께의 SiO2를 형성한 뒤, 채널 형성을 위해 RF sputter를 이용하여 70 nm 두께의 a-IGZO를 증착하였다. 이후에 소스와 드레인 전극에는 150 nm 두께의 In-Sn-O (ITO)를 RF sputter를 이용하여 증착하였고, ALD 방법을 이용하여 tunnel layer에 AlOx 5 nm, trap layer에 HfOx 20 nm, blocking layer에 AlOx 30 nm를 증착하였다. 최종적으로, 상부 게이트 전극을 형성하기 위해 electron beam evaporator를 이용하여 platinum (Pt) 150 nm를 증착하였고, 계면 결함을 최소화하기 위해 퍼니스에서 질소 가스 분위기, $400^{\circ}C$, 30 분의 조건으로 열처리를 했다. 측정 결과, 103 번의 program/erase를 반복한 endurance와 104 초 동안의 retention 측정으로부터 큰 열화 없이 메모리 특성이 유지되는 것을 확인하였다. 결과적으로, high-k 물질과 산화물 반도체는 고성능과 고집적화가 요구되는 향후 플래시 메모리의 핵심적인 물질이 될 것으로 기대된다.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.129-136
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• 1999

Transient transfection assay has been done to evaluate whether the c-jun activation would be prerequisite to the induction of permissiveness against human cytomegalovirus using in vitro cell model in which U937 has been induced to express CD11b and CD14 to become potential monocyte/macrophage cells by TPA treatment. U937 cells were treated with $10\;{\mu}M$, $50\;{\mu}M$ or $100\;{\mu}M$ of TPA. The cell morphology change was observed and the expression of the CD11b and CD14 was confirmed by FACS. Differentiated cells were transfected with pJLuc reporter vector which contained the wild type murine c-jun promoter spanning the SP1, CTF, ATF/CREB and MEF-2 binding sites upstream of the firefly luciferase gene. After 48 hrs of transfection, the cells were infected with HCMV Towne strain and the luciferase activity was assessed at 1 hand 4 h pi. The transfection assay showed no activation of the c-jun promoter at 1 h pi, instead, it showed 2 times increase of the its activity at 4 h pi. There was no difference of the c-jun promoter activation between TPA treated and untreated U937 cells, implying that c-jun activation might not be prerequisite for allowing cells to be premissive to HCMV, although HCMV infection itself could activate c-jun promoter.