• 산업경영시스템학회지
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• 제44권2호
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• pp.15-23
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• 2021

Most of the open-source decision tree algorithms are based on three splitting criteria (Entropy, Gini Index, and Gain Ratio). Therefore, the advantages and disadvantages of these three popular algorithms need to be studied more thoroughly. Comparisons of the three algorithms were mainly performed with respect to the predictive performance. In this work, we conducted a comparative experiment on the splitting criteria of three decision trees, focusing on their interpretability. Depth, homogeneity, coverage, lift, and stability were used as indicators for measuring interpretability. To measure the stability of decision trees, we present a measure of the stability of the root node and the stability of the dominating rules based on a measure of the similarity of trees. Based on 10 data collected from UCI and Kaggle, we compare the interpretability of DT (Decision Tree) algorithms based on three splitting criteria. The results show that the GR (Gain Ratio) branch-based DT algorithm performs well in terms of lift and homogeneity, while the GINI (Gini Index) and ENT (Entropy) branch-based DT algorithms performs well in terms of coverage. With respect to stability, considering both the similarity of the dominating rule or the similarity of the root node, the DT algorithm according to the ENT splitting criterion shows the best results.

• Smart Structures and Systems
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• 제18권5호
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• pp.1063-1085
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• 2016

Taking advantage of the high sensitivity and long-distance detection capability of acoustic emission (AE) technique, this paper focuses on the crack detection in rail head, which is one of the most vulnerable parts of rail track. The AE source location and noise cancellation were studied on the basis of practical rail profile, material and operational noise. In order to simulate the actual AE events of rail head cracks, field tests were carried out to acquire the AE waves induced by pencil lead break (PLB) and operational noise of the railway system. Wavelet transform (WT) was first utilized to investigate the time-frequency characteristics and dispersion phenomena of AE waves. Here, the optimal mother wavelet was selected by minimizing the Shannon entropy of wavelet coefficients. Regarding the obvious dispersion of AE waves propagating along the rail head and the high operational noise, the wavelet transform-based modal analysis location (WTMAL) method was then proposed to locate the AE sources (i.e. simulated cracks) respectively for the PLB-induced AE signals with and without operational noise. For those AE signals inundated with operational noise, the Hilbert transform (HT)-based noise cancellation method was employed to improve the signal-to-noise ratio (SNR). Finally, the experimental results demonstrated that the proposed crack detection strategy could locate PLB-simulated AE sources effectively in the rail head even at high operational noise level, highlighting its potential for field application.

• 한국지리정보학회지
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• 제24권1호
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• pp.26-39
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• 2021

본 연구는 낙동강수계 하류에 있는 서낙동강 유역을 대상으로 유역 및 오염원 특성을 조사하여 TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution) 방법에 따른 소유역별 비점오염 취약지역을 평가하였다. 선정 방법은 평가인자 선정, 가중치 산정, 평가인자와 가중치를 통한 비점오염 취약지역 선정으로 구성되어 있다. 가중치 산정방법으로는 엔트로피법을 이용하고 평가기법으로는 다기준 의사결정 기법(Multi-criteria Decision Making, MCDM)인 TOPSIS를 이용하였다. 지표 자료는 2018년을 기준으로 수집하였으며, 전국오염원조사 자료와 국가통계자료를 활용하였다. 취약한 유역들은 대부분 도시화가 많이 진행된 지역이며 거주 인구수가 많고 산업시설 및 토지계 중 대지면적 비율이 높은 유역으로 평가되었다. 본 연구를 통하여 신뢰도 높은 비점오염 취약 평가를 위해서는 다양한 가중치 방법론의 접근이 필요하고 비점오염원에 영향을 주는 인자들에 대한 과학적 분석 및 영향성에 대한 고찰이 필요할 것으로 판단된다.

• Current Optics and Photonics
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• 제2권6호
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• pp.532-539
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• 2018

Multiple LED arrays can be utilized in visible-light communication (VLC) to improve communication efficiency, while maintaining smart illumination functionality through dimming control. This paper proposes a modulation scheme called "Spatial Intensity Modulation" (SIM), where the effective number of turned-on LEDs is employed for data modulation and dimming control in VLC systems. Unlike the conventional pulse-amplitude modulation (PAM), symbol intensity levels are not determined by the amplitude levels of a VLC signal from each LED, but by counting the number of turned-on LEDs, illuminating with a single amplitude level. Because the intensity of a SIM symbol and the target dimming level are determined solely in the spatial domain, the problems of conventional PAM-based VLC and related MIMO VLC schemes, such as unstable dimming control, non uniform illumination functionality, and burdens of channel prediction, can be solved. By varying the number and formation of turned-on LEDs around the target dimming level in time, the proposed SIM scheme guarantees homogeneous illumination over a target area. An analysis of the dimming capacity, which is the achievable communication rate under the target dimming level in VLC, is provided by deriving the turn-on probability to maximize the entropy of the SIM-based VLC system. In addition, a practical design of dimmable SIM scheme applying the multilevel inverse source coding (MISC) method is proposed. The simulation results under a range of parameters provide baseline data to verify the performance of the proposed dimmable SIM scheme and applications in real systems.

• 대한기계학회논문집
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• 제8권6호
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• pp.564-568
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• 1984

본 연구에서는 실제 동력 발생장치에 사용되는 사이클은 장치의 크기를 고려 한 파라미터의 선정이 필요하며, 여기서는 열전달에 의한 비가역성을 고려할 때의 열 기관 사이클을 출력에 중점을 두어 해석하고자 한다. 그리고 비가역성에 의한 엔트 로피 생성량과 출력과의 관계도 살펴볼 것이다.

• 전자공학회논문지B
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• 제32B권11호
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• pp.1383-1392
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• 1995

In this paper, the method to incorporate TCVQ(Trellis Copded Vector Quantizer) into the encoding of the wavelet trans formed(WT) image followed by a variable length coding(VLC) or an entropy coding(EC) is considered. By WT, an original image is separated into 10 bands with various resolutions and directional components. TCVQ used to compress these WT coefficients is a finite state machine that encodes the input source on the basis of the current input and the current state. Wavelet basis used in this paper is designed by orthogonal spline function. A modified set partitioning algorithm to Wang's is also presented. A simple modification to Wang's algorithm gives a highly time-efficient result. Proposed WT-TCVQ encoder shows a very competitive result, giving 37.46dB in PSNR at 1.002bpp when encoding 512$\times$512 LENA.

• 한국수소및신에너지학회논문집
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• 제25권6호
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• pp.594-601
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• 2014

Rare-earth (RE) nitrides can be used as magnetocaloric materials in low temperature. They exhibit ferromagnetism and have Curie temperature in the region from 6 to 70 K. In this study, Holmium nitride (HoN) nano particles were prepared through plasma arc discharge technique and their magnetocaloric properties were studied. Nitrogen gas ($N_2$) was employed as an active element for arc discharge between two electrodes maintained at a constant current. Also, it played an important role not only as a reducing agent but also as an inevitable source of excited nitrogen molecules and nitrogen ions for the formation of HoN phase. Partial pressure of $N_2$ was systematically varied from 0 to 28,000 Pa in order to obtain single phase of HoN with minimal impurities. Magnetic entropy change (${\Delta}S_m$) was calculated with data set measured by PPMS (Physical Property Measurement System). The as-synthesized HoN particles have shown a magnetic entropy change ${\Delta}S_m$) of 27.5 J/kgK in applied field of 50,000 Oe at 14.2 K thereby demonstrating its ability to be applied as an effective magnetic refrigerant towards the re-liquefaction of hydrogen.

• 대한토목학회논문집
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• 제32권1B호
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• pp.21-27
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• 2012

T. Linde가 제안한 HLLL 기법에서는 일반화된 엔트로피 함수의 도입으로 중앙파가 평가되므로 모든 파속이 초기 상태로부터 결정된다. HLLE 기법과 달리 Roe의 선형화 기법과 완전히 결별되고 HLLC 기법과 달리 정확해에 의존되지 않으므로 모태인 HLL 기법의 온전한 계승으로 볼 수 있다. 이 연구에서는 생성항이 없는 1차원 천수방정식에 농도와 관련된 보존변수를 추가한 지배방정식에 대해 총 에너지를 일반화된 엔트로피 함수로 두고 HLLL 기법을 적용하여 모형을 구성하였다. 정확해가 알려진 세 경우에 대해 모의한 결과, 1차 정확도 수치해의 한계에도 불구하고, 대체로 정확해와 잘 일치하였다. HLLL 기법은 그 외 HLL 형 기법에 비해 우수한 것으로 나타났다. 특히, 물이 빠져 바닥이 드러나는 경우에서 그 전선이 비교적 정확하게 포착되었다. 다만, 그 외 기법에 비해 계산 시간이 더 오래 걸리는 단점이 드러났다.

• 한국측량학회지
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• 제24권4호
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• pp.327-334
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• 2006

항공 영상은 지도 제작과 지상 피복 분류와 같은 간단한 목적뿐만 아니라 도시계획, 환경, 재난, 교통 등과 같은 사회적인 목적에서 필수적이다. 그러나 영상이 취득될 때 간섭되는 그림자는 지상 정보를 해석하는데 방해요소로 작용하고, 자신의 업무 및 연구에 사용하려는 사용자에게 제한적인 요인으로 작용한다. 일반적으로 그림자는 건물과 표면 지형 등에 의해 발생하며 세부적인 원인으로 이러한 지형에 의한 광원의 변화에 의해 생성된다. 본 연구는 그림자를 제거하기 위하여 단일 영상만을 사용하며 영상의 원 출처 및 촬영상태의 사전 정보 없이 처리하였다. 또한 그림자 경계 마스크를 제작하기 위하여 엔트로피 최소화 기법을 사용한 1차원 흑백 불변 영상(invariant images)과 Canny 경계 검출법을 적용하였으며, 최종적으로 퓨리어(Fourier) 주파수 공간에서의 필터링을 통한 고유 영상(intrinsic images)을 제작함으로써 3차원의 컬러 정보를 복원하고 그림자를 제거하였다.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.758-762
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• 2007

A new alkyldithiocarbonate (xanthate), as sodium salts, C2H5OCS2Na, was synthesized by the reaction between CS2 with ethyl alcohol in the presence of NaOH. The new xanthate was characterized by 1H NMR, IR and elemental analysis. Then, the new synthesized compound was examined for functional study of cresolase activity of Mushroom Tyrosinase (MT) from a commercial source of Agricus bisporus in 10 mM phosphate buffer pH 6.8, at three temperatures of 10, 20 and 33℃ using UV spectrophotemetry. 4-[(4-methylphenyl)- azo]-phenol (MePAPh) was used as a synthetic substrate for the enzyme for cresolase reaction. The results show that ethyl xanthate can activate or inhibit the cresolase activity of mushroom tyrosinase depending to the concentration of ethyl xanthate. It was concluded that the enzyme has two distinct sites for ethyl xanthate. The first one is a high-affinity activation site and the other is a low-affinity inhibition site. Activation of the enzyme in the low concentration of ethyl xanthate arises from increasing the affinity of binding for the substrate as well as increasing the enzyme catalytic constant. The affinity of ligand binding in the activation site is decreased by increasing of the temperature, which is the opposite result for the inhibition site. Hence, the nature of the interaction of ethyl xanthate is different in two distinct sites. The binding process for cresolase inhibition is only entropy driven, meanwhile the binding process for cresolase activation is not only entropy driven but also enthalpy driven means that hydrophobic interaction is more important in the inhibition site.