• 유통과학연구
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• 제17권12호
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• pp.23-32
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• 2019

Purpose As consumer awareness grows, the importance of CSR becomes even more important for long-term growth. In response to this current trend, the purpose of this study is to analyze the effect of CSR activities on business performance for logistics companies. Research design, data, and methodology - Between CSR activities and growth, there was a generally positive(+) relationships between activities such as donation and volunteerism and the growth of the enterprise. In terms of the relationship between environmental factors and growth, negative results were expressed. In case of profitability, improved welfare for workers has had a positive impact on corporate profitability. Results - With respect to stability, a high proportion of equity capital is not considered to be more active in SCR activities. Significant negative results were given between the minimum factors for entry, transportation, and noise generation factors and the ratio of liabilities, which are representative friction factors in the community. Conclusions - With respect to stability, a high proportion of equity capital is not considered to be more active in SCR activities. Significant negative results were given between the minimum factors for entry, transportation, and noise generation factors and the ratio of liabilities, which are representative friction factors in the community.

• 대한기계학회논문집
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• 제18권4호
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• pp.1057-1063
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• 1994

An instantaneous frequency analysis is a technique to examine a signature for the rotating machinery if the signal has several transitions within a cycle. This paper discusses the conditions of existing negative frequency components in the instantaneous frequency. By using a signal consisted of two frequency components, the instantaneous frequency analysis is conducted while the amplitude ratio between two frequency components has been changed. The analysis shows that, depending on the amplitude ratio, the instantaneous frequencies have averaged, zero-valued, or negative components. It turns out that the negative-valued instantaneous frequencies, which have been regarded as the noise effect, are the consequence of the calculation process for the multisignal components. The criteria of existing the negative values in instantaneous frequencies is given in terms of the relative amplitude ratio and the frequency difference. Especially when the amplitude ratio approaches to 1, the instantaneous frequency fluctuates ${\pm}\infty$ in theory, which implies that instantaneous frequency has unstable region around the amplitude ratio, 1.Also, as the frequency difference between major signal components is increased, the region of existing negative instantaneous becomes broader. In an instantaneous frequency analysis, therefore, a narrow band analysis is suggested, with extreme care if the amplitude ratio approaches to 1. In this paper, a vibration signal monitored from a rotating machinery is also examined as an application example in order to show the existence of negative instantaneous frequencies components.

• Journal of electromagnetic engineering and science
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• 제4권4호
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• pp.168-174
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• 2004

A bandwidth-enhanced and phase noise-improved differential LC-tank VCO is proposed in this paper. By connecting the varactors to the bases of the cross-coupled transistors of the proposed LC-tank VCO, its input negative resistance has been widened. Also, the feedback capacitor Cc in the cross-coupling path of the proposed LC-tank VCO attenuates the output common-mode level modulated by the low-frequency noise because the modulated common-mode level jitters the varactor bias point and degrades phase noise. Compared with the fabricated conventional LC-tank VCO, the proposed LC-tank VCO demonstrates $200\;\%$ enhancement in tuning range, and 6 - dB improvement in phase noise at 6 MHz offset frequency from 5.4-GHz carrier. We achieved the phase noise of - 106 dBc/Hz at 6 MHz offset, and $10\;\%$ tuning range from the proposed LC-tank VCO. The proposed LC-tank VCO consumes 12 mA at 2.5 V supply voltage.

• 해양환경안전학회지
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• 제14권4호
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• pp.275-287
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• 2008

소음의 외부효과는 현대사회에서 흔히 발견되는 문제라고 할 수 있다. 소음은 재산적 피해와 같은 외부효과를 발생시키며, 따라서 소음으로 인한 재산피해를 평가하고 효과적 해결책을 찾아내는 연구는 매우 중요하다고 할 수 있다. 분석결과는 통계적 유의성이 있으며, 소음이 재산적 가치에 부정적 효과가 있음을 보여 주고 있다. 모형의 주요 결과로는 소음 단위(데시빌)당 피해액이 추정(5,000 달러${\ast}$로그(dB))되었고, 추정된 소음피해함수(잠재가격함수)는 소음의 한계효과가 감소함을 나타내고 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.465-468
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• 2004

In this paper, we describe the design and implementation of the new current-current negative feedback (CCNF) voltage-controlled oscillator (VCO), which suppresses 1/f induced low-frequency noise. By means of the CCNF, the high-frequency noise as well as the low-frequency noise is prevented from being converted into phase noise. The proposed CCNF VCO shows 11-dB reduction in phase noise at 10 kHz offset, compared with the conventional differential VCO. The phase noise of the proposed VCO is -87 dBc/Hz at 10 kHz offset frequency from 5.5-GHz carrier. The proposed VCO consumes 14.0 mA at 2.0 V supply voltage, and shows single-ended output power of -12.0 dBm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.727-734
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• 2008

This research presents a laboratory study about difference of subjective response between with and without pictures. A main source is impulsive sound caused by leisure shooting. The sources are sampled from outdoor noise and their levels range from 40 to 75 dB at the interval of 5dB. The noise unit is based on A-weighted sound exposure level (ASEL; $L_{AE}$). To make equal ASEL of outdoor noise, finite impulse response (FIR) filter is applied to the originally sampled source to include the effect of distance attenuation. The evaluation method of the jury test adopted a Semantic Difference(SD) Method. The intersection point which two lines crossed was used as reference point. The intersecting point of mean response rating between with and without pictures was approximately 44ASEL and that of %HA was about 60ASEL. In the result of the test, the negative effect of pictures was given at a lower levels than intersection point while the positive effect was given at a higher levels than that.

• 한국소음진동공학회논문집
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• 제18권7호
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• pp.775-782
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• 2008

In this study, ground vibrations and aero space noises that is produced by the PRD(percussion rotary drill) were analyzed by work processes. Ground vibration equations were suggested by $2.798(SD)^{-0.793}$, $3.485(SD)^{-0.793}$, $3.705(SD)^{-0.793}$, according to experiment result, and these equations have reliability of 50%, 90%, 95%, respectively. Ground vibration values by the PRD method correspond to level of $5{\sim}34%$ of values that are assumed by the Attewell & Farmer's equation, and these result compares in reliability 50%. Also, those values were analyzed that correspond to level of $12{\sim}26%$ of ground vibration values by the Prof. Park etc.'s equations. But, the aero space noise was evaluated that is assumed by 88.9 dB(A) at separated distance 50m and is not satisfied even 85dB(A) that is the most negative noise value that present in domestic noise standard. The PRD method was analyzed that noise decrease effect exists hardly comparing with general pile driving method of construction. When is based in these results, the PRD method is judged that it is desirable that classify by the Low-vibration method more than the Non-violation noise method.

• 한국전자파학회논문지
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• 제13권8호
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• pp.748-753
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• 2002

본 논문은 저잡음 특성을 갖는 구조의 부성저항을 이용하여 공진부의 손실을 보상하는 새로운 구조의 공진회로를 제안하고 있다. 또한 여파기 설계시, noise해석을 통하여 최적의 noise 특성을 갖도록 능동 대역통과 여파기의 설계방법을 제시하고 있다. FET에 의해 만들어진 능동 커패시터는 부성저항과 커패시턴스 성분을 가지고 있으며, 부성저항에 의해 공진회로를 구성하는 인덕터 소자의 손실을 보상해 준다. 기존의 능동 여파기는 대개 높은 잡음지수를 가지는데 반하여 제안된 능동 여파기는 능동소자의 잡음특성을 최소화하는 구조로 설계되었다. 잡음지수를 최소화함으로서 RFIC나 MMIC와 같은 집적회로로서 수신단 Front-end설계에 응용할 수 있다. 제작된 2단 능동대역통과 여파기는 1.9 GHz 대역에서 설계되었으며, 측정된 삽입손실은 0 dB, 잡음지수는 2.6 dB, 그리고 OIP3는 8 dBm의 특성을 얻었다

• 한국정보통신학회논문지
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• 제18권9호
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• pp.2176-2182
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• 2014

이 논문에서는 기존의 위상고정루프에 전원 잡음 제거 회로를 추가한 위상고정 루프 회로를 제안한다. 제안한 구조는 주파수 전압 변환기를 변형한 전원 잡음 제거 회로를 사용하여 임의의 전원 잡음에 대해 보상하여 동작한다. 전원 잡음 제거 회로를 사용하여 전원 잡음에 의해 발생하는 지터의 크기를 1/3로 줄였다. 제안한 위상 고정 루프는 0.18um CMOS 공정을 사용 하여 HSPICE 시뮬레이션을 통해 예측되는 결과를 검증하였다.

• Journal of the Korean Statistical Society
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• 제21권2호
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• pp.167-177
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• 1992

In this paper, we investigate the limiting distribution of $M_n = max (X_1, X-2, \cdots, X_n)$ in the infinite moving average process ${X_t = \sum c_i Z_{t-i}}$ generated from i.i.d. negative binomial variables $Z_i$'s. While no limit result is possible, nonetheless asymptotic bounds are derived. We also present the tail behavior of $X_t$, i.e., weighted sum of i.i.d. random variables. This continues a study made by Rootzen (1986) for discrete innovation sequences.