• Korean Chemical Engineering Research
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• 제57권5호
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• pp.735-742
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• 2019

이온 선택성 표면이 가지는 파상구조와 전기와류 불안정성 간의 전기동역학적 상호작용을 수치해석을 통하여 연구하였다. 유한요소법을 이용하여 전기장-이온 이동현상-유동장을 완전결합 해석을 하였다. 이를 통해 파상구조가 제공하는 전기와류 생성 기작인 Dukhin's mode의 유효성 및 역할을 제시하였다. Runinstein's mode와 경쟁관계에 놓이는 Dukhin's mode는 (i) 과한계 영역으로의 전이 전압을 낮춰주고 (ii) 혼돈계인 과한계 영역에서 전류를 비선형적으로 증가시켜준다. 또한, (iii) 전기와류 불안정성에서 발생하는 비효율적 혼합의 원인인 고주파수 Fourier 성분을 배제하여 전기와류의 혼합 효율을 상승시켜 준다. 결론적으로, 본 연구에서 제시한 기작은 전기투석, 화학전지 등의 이온 선택성 이동현상 시스템에 대한 에너지 효율적인 기작으로 활용 가능할 것이다.

• 한국정보통신학회논문지
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• 제24권2호
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• pp.321-324
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• 2020

In this work, we developed a selective etching process for GaN that is a key process in p-GaN/AlGaN/GaN enhancement-mode (E-mode) power switching field-effect transistor (FET) fabrication. In order to achieve a high current density of p-GaN/AlGaN/GaN E-mode FET, the p-GaN layer beside the gate region must be selectively etched whereas the underneath AlGaN layer should be maintained. A selective etching process was implemented by oxidizing the surface of the AlGaN layer and the GaN layer by adding O2 gas to Cl2/N2 gas which is generally used for GaN etching. A selective etching process was optimized using Cl2/N2/O2 gas mixture and a high selectivity of 53:1 (= GaN/AlGaN) was achieved.

• 대한방사성의약품학회지
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• 제6권2호
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• pp.146-154
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• 2020

Selective installation of proteins using chemical reagents is important for the development of potential biomaterials for the treatment of human diseases. However, modification in a chemo- and regioselective manner under physiological conditions is a great challenge due to the presence of multiple reactive centers in the protein. Currently, the majority of conjugations are limited to lysine (Lys)- and cysteine (Cys)-selective reagents. Thus, they have been extensively studied. Apart from Lys and Cys, widespread site selectivity has been recently achieved through most of the 20 naturally occurring amino acid-bearing reactive functional groups. Consequently, this review focused on several recent achievements in site-selective modification of the rarest amino acid backbones (e.g., methionine, serine, glutamic acid, and tyrosine).

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.15-17
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• 2022

볼 베어링 선택조립 시스템에서 잉여부품을 최소화하기 위해서는 각 부품의 치수 분포를 파악하여 선택 확률을 최적화하여야 하지만, 복잡한 시스템은 생산 공정에 지연이 일으킨다. 본 논문에서는 볼 베어링 선택조립 시스템에서 빠르고 간단하게 선택 우선순위를 결정할 수 있는 군집 우선 선택 알고리즘을 제안한다. 그리고 실제 볼 베어링 선택조립 공정에서 수집한 데이터로 모의 상황을 가정하고, 군집 우선 선택 알고리즘과 기존 알고리즘을 시뮬레이션하여 잉여부품 발생률과 연산소요시간을 평가한다. 시뮬레이션 결과, 군집 우선 선택 알고리즘이 기존 알고리즘에 비하여 83.8% 적은 잉여부품을 발생하였고, 연산소요시간도 39.7% 단축되었다.

• 한국정보전자통신기술학회논문지
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• 제16권5호
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• pp.301-306
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• 2023

Attention is a fundamental aspect in the cognitive process of human. Cognitive system of human body requires to focus on selected information among a vast amount of information from sensory organs. It has widely studied that various environmental factors affected the level of attention; however, few researches have aimed to the effect of direct cryotherapy. In this research, level of attention was studied comparing sub-indexes of FAIR test between groups with different duration of direct cryotheapy to the back of neck. FAIR test is a evaluation tool for visual attention consisting of three sub-indexes. Selective attention, accuracy of attention, and persistence of attention can be independently analyzed by FAIR test. In the analysis of selective attention, cryotherapy for 5 to 20 minutes showed higher result than cryotherapy for 40 minutes. In the analysis of persistence of attention, cryotherapy for 5 to 15 minutes showed higher result than cryotherapy for 40 minutes. Overall, selective attention and persistence of attention turns out to be maximized between 5 to 20 minutes of cryotherapy and tends to decrease afterwards. However, accuracy of attention does not seem to be affected by the duration of cryotherapy. Correlation between selective attention and the skin temperature by cryotherapy tends to be negative supporting the findings by ANOVA and post-hoc test. Correlation between persistence of attention and the skin temperature showed similar results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.699-702
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• 1998

This paper presents a 500MHz 1.1㎱ 32kb synchronous CMOS SRAM macro using $0.35\mu\textrm{m}$ CMOS technology. In order to operate at high frequency and reduce power dissipation, the designed SRAM macro is realized with optimized decoder, multi-point sense amplifier(MPSA), selective precharge scheme and etc. Optimized decorder and MPSA respectively reduce 50% and 40% of delay time. Also, a selective precharge scheme reduces 80% of power dissipation in that part.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.269-274
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• 2001

This paper describes the experimental results on direct selective laser sintering of WC-Co mixture. The experiments were carried out within an air, argon and nitrogen atmosphere. The main problem occurred during sintering within an air atmosphere was oxidation of WC-Co mixture. As the power of laser is increased and scanning speed is decreased, more severe oxidation takes place. Within an argon and nitrogen atmosphere the oxidation is reduced significantly. As the energy density is increased the thickness of the sintered layer is increased.

• 지구물리
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• 제4권4호
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• pp.231-238
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• 2001

In this paper, an efficient LP method ofr discrete harmonic spectra is proposed and discussed. A new efficient LP method is a combination of recursive and frequency selective LP. While the recursive LP provides better spectral matching in spectral hills, frequency selective LP eliminates numerical instability and improves spectral matching when the harmonics are confined in the low frequncy region. The proposed LP method is applied to the HILN coder. Simulation results using a verification model(VM) software for real audio signals show a definite trend of significant improvement.

• ETRI Journal
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• 제28권4호
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• pp.506-508
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• 2006

A frequency selective surface (FSS), whose unit cell consists of a ternary tree loop loaded with a modified tripole, is proposed to block multiple frequency bands. Target frequency bands correspond to Korean personal communication services, cellular mobile communication, and 2.4 GHz industrial, scientific, and medical bands. Through the adjustment of inter-element and inter-unit cell gaps, and adjustment of the length of elements, we present an FSS design method that makes the precise tuning of multiple resonance frequencies possible. Additionally, to verify the validity of our approach, simulation results obtained from a commercial software tool and experimental data are also presented.

• 한국세라믹학회지
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• 제19권1호
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• pp.19-23
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• 1982

The technique to determine the components in the supersulphated slag cement is discussed by several selective extraction analyses. Accordingly, the rate of hydration reaction of supersulphated slag cement could be quantitatively measured by the following 3 kinds of the selective extraction analyses. (1) Determination of unreacted slag - a salicylic acid, acetone.methanol solution (2) Determination of free $CaSO_4$ - a half saturated lime water (3) Determination of free $Ca(OH)_2$ - glycerine.alcohol solution