• 대한수학회보
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• 제59권1호
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• pp.141-154
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• 2022

Let R be a commutative ring with identity. Denote by w𝒫_w the class of weak w-projective R-modules and by w𝒫_w^⊥ the right orthogonal complement of w𝒫_w. It is shown that (w𝒫_w, w𝒫_w^⊥) is a hereditary and complete cotorsion theory, and so every R-module has a special weak w-projective precover. We also give some necessary and sufficient conditions for weak w-projective modules to be w-projective. Finally it is shown that when we discuss the existence of a weak w-projective cover of a module, it is enough to consider the w-envelope of the module.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1803-1806
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• 2003

This paper presents a H/W module that executes a fragile watermarking algorithm. The module inputs sequentially quantized DCT values, encodes watermark and then outputs watermarked DCT coefficients. A fragile and invisible watermarking algorithm is adopted, modified and enhanced here to reduce H/W size and image degradation. The module can be directly inserted between DCT quantizer and VLC encoder in wide spread JPEG/MPEG encoder. The module is expected to be used for real-time authentication purpose in DVR(Digital Video Recorder) or digital cameras.

• 대한수학회보
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• 제49권3호
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• pp.601-608
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• 2012

The following statements for an infra-Krull domain $R$ are shown to be equivalent: (1) $R$ is a Krull domain; (2) for any essentially finite $w$-module $M$ over $R$, the torsion submodule $t(M)$ of $M$ is a direct summand of $M$; (3) for any essentially finite $w$-module $M$ over $R$, $t(M){\cap}pM=pt(M)$, for all maximal $w$-ideal $p$ of $R$; (4) $R$ satisfies the $w$-radical formula; (5) the $R$-module $R{\oplus}R$ satisfies the $w$-radical formula.

• 새물리
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• 제68권11호
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• pp.1215-1224
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• 2018

Most solar photovoltaic (PV) modules frequently get shadowed, completely or partially, resulting in a reduction of PV generation. This paper presents and compares the results from simulations and experimental measurements of the power output from a single PV module under various shading conditions. The study was carried out with a 90 W PV module and a 250 W PV module. The shaded area was increased from 0 to 100% for both variable and constant irradiances to analyze the effect of fluctuations in the solar irradiance certain shading conditions. The effect of shading for irradiance levels from 100 to $900W/m^2$ was investigated. Results showed that for every $100W/m^2$ decrease in the solar irradiance level, the power output decreased by 9, 0.7 and 1.5 W at 0, 25 and 50% shading, respectively. For solar irradiance levels higher than $500W/m^2$, the temperature increased by 1.6, 2.7 and $1.1^{\circ}C$ at 0, 25 and 50% shading, respectively, for every $100W/m^2$ increase in the irradiance.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.321-322
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• 2015

Thermoelectric power generation has emerged as a promising alternative technology because it offers a potential application in the direct conversion of waste heat into electric energy. The performance of thermoelectric power generator depends on thermoelectric materials and thermoelectric power module designs. The main objective of this study is to design a 100W thermoelectric generation (TEG) module and to get optimal operating conditions of the module. The design and performance of the TEG module will be presented.

• 대한수학회보
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• 제50권6호
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• pp.1905-1914
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• 2013

Let D be an integral domain with quotient field K, M a torsion-free D-module, X an indeterminate, and $N_v=\{f{\in}D[X]|c(f)_v=D\}$. Let $q(M)=M{\otimes}_D\;K$ and $M_{w_D}$={$x{\in}q(M)|xJ{\subseteq}M$ for a nonzero finitely generated ideal J of D with $J_v$ = D}. In this paper, we show that $M_{w_D}=M[X]_{N_v}{\cap}q(M)$ and $(M[X])_{w_{D[X]}}{\cap}q(M)[X]=M_{w_D}[X]=M[X]_{N_v}{\cap}q(M)[X]$. Using these results, we prove that M is a strong Mori D-module if and only if M[X] is a strong Mori D[X]-module if and only if $M[X]_{N_v}$ is a Noetherian $D[X]_{N_v}$-module. This is a generalization of the fact that D is a strong Mori domain if and only if D[X] is a strong Mori domain if and only if $D[X]_{N_v}$ is a Noetherian domain.

• International Journal of Advanced Culture Technology
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• 제7권4호
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• pp.236-241
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• 2019

This paper will read about a multichannel frequency-modulated continuous wave (FMCW) radar sensor with switching transmit (TX) antennas is developed at W-band. To achieve a high angular resolution, a uniform linear array consisting of 5 switching-TX and 12 receive (RX) antennas is employed with the digital beamforming technique. The overall radar front-end module comprises a W-band transceiver and TX/RX antennas. A multichannel transceiver module consists of 5 up-conversion and 12 down-conversion channels, where one of the TX channels is sequentially switched ON. For developing transmitter, we developed an HPA (high power amplified) MMIC chip for W-band radar system and fabricated a transmitter module using this chip. In order to develop the W-band transmitter, we analyzed the important antenna transition structure from HPA MMIC line to W/G (Waveguide)antenna via M/S(microstrip) and fabricated it with 5 transmission channels. As a result, the output power of the transmitter was within 1 dB of the error range after analysis and measurement under normal temperature and environmental conditions.

• 조명전기설비학회논문지
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• 제29권12호
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• pp.15-21
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• 2015

We proposed 50W-LED modules of using Heat-pipe and Stack-fin and produced LED modules was evaluated heat dissipation characteristics with comparison of the conventional die-casting type. It verified the application of products by applying it to 150W-LED road luminaires through simulation. The LED module was measures aimed design temperature of the Stack-fin and showed 26% upward heat dissipation effect than a conventional die-casting type. The luminous efficacy of 150W-LED road luminaires using this LED module reached over 112lm/W, and the simulation results showed average of horizontal luminance, overall luminance uniformity($U_O$) and lane luminance uniformity($U_I$) that is suitable for five-lane road with the KS standards.

• 전자공학회논문지SC
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• 제48권2호
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• pp.1-8
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• 2011

수중로봇 S/W 프레임웍은 센서 데이터 처리, 추진기 제어, 인지 및 행위 제어 등의 다양한 하위모듈로 구성된다. 로봇의 성능은 알고리즘 자체의 우수성 뿐 아니라 그 구현에도 큰 영향을 받는데, 효과적인 구현에 가장 큰 영향을 미치는 부분 중의 하나는 모듈간의 신호 및 데이터 전달을 담당하여 센싱 및 제어 주기에 영향을 주는 데이터 공유 모듈의 효율성이다. 이상적인 데이터 공유 모듈은 시스템의 H/W 및 S/W 구성에 상관없이 데이터 싱크로부터 데이터 소스에 지연 없이 접근할 수 있게 해야 한다. 그러나 실제에 있어서는 시스템 구성 특성에 의한 데이터 소스 모듈의 접근 처리 용량 한계, 네트워크 지연 및 운영체제의 스케쥴링 등으로 인하여 다양한 접근 지연이 요인이 존재한다. 본 논문은 수중로봇과 같이 소수의 컴퓨터로 이뤄진 소규모 분산시스템에서 이러한 접근 지연을 효과적으로 처리하기 위한 데이터 공유 모듈 구조 및 프로그래밍 모델을 제안하고 있다.

• 대한수학회보
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• 제55권2호
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• pp.649-657
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• 2018

Let R be a commutative ring. In this paper, the w-projective Basis Lemma for w-projective modules is given. Then it is shown that for a domain, nonzero w-projective ideals and nonzero w-invertible ideals coincide. As an application, it is proved that R is a Krull domain if and only if every submodule of finitely generated projective modules is w-projective.