• Title/Summary/Keyword: Bias problem

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Decision Methodology for LNG Plant FEED Evaluation using Analytic Hierarchy Process (LNG 플랜트 프로젝트의 기본설계 평가방법에 관한 연구)

  • Park, Jong-Hwa;Cho, Dae-Myeong
    • Journal of the Korean Institute of Gas
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    • v.20 no.3
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    • pp.52-58
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    • 2016
  • In this study, evaluation method for LNG plant FEED is suggested and its validity is confirmed using a well-known decision making technique of Analytic Hierarchy Process (AHP). It is a pairwise comparison technique which can be used when multiple options must be considered for a single decision making problem. In order to develop an objective decision methodology, various decision parameters, sub-parameters as well as the concept of scale of assessment were introduced, and its consistency among these parameters was also checked by calculating the consistency index (C.I.). The methodology suggested in this article will contribute in evaluation of LNG plant FEED with less bias and subjectivity associated with the decision making procedure.

Adjustment of A Simplified Satellite-Based Algorithm for Gross Primary Production Estimation Over Korea

  • Pi, Kyoung-Jin;Han, Kyung-Soo;Kim, In-Hwan;Lee, Tae-Yoon;Jo, Jae-Il
    • Korean Journal of Remote Sensing
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    • v.29 no.3
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    • pp.275-291
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    • 2013
  • Monitoring the global Gross Primary Pproduction (GPP) is relevant to understanding the global carbon cycle and evaluating the effects of interannual climate variation on food and fiber production. GPP, the flux of carbon into ecosystems via photosynthetic assimilation, is an important variable in the global carbon cycle and a key process in land surface-atmosphere interactions. The Moderate-resolution Imaging Spectroradiometer (MODIS) is one of the primary global monitoring sensors. MODIS GPP has some of the problems that have been proven in several studies. Therefore this study was to solve the regional mismatch that occurs when using the MODIS GPP global product over Korea. To solve this problem, we estimated each of the GPP component variables separately to improve the GPP estimates. We compared our GPP estimates with validation GPP data to assess their accuracy. For all sites, the correlation was close with high significance ($R^2=0.8164$, $RMSE=0.6126g{\cdot}C{\cdot}m^{-2}{\cdot}d^{-1}$, $bias=-0.0271g{\cdot}C{\cdot}m^{-2}{\cdot}d^{-1}$). We also compared our results to those of other models. The component variables tended to be either over- or under-estimated when compared to those in other studies over the Korean peninsula, although the estimated GPP was better. The results of this study will likely improve carbon cycle modeling by capturing finer patterns with an integrated method of remote sensing.

A Bayesian Poisson model for analyzing adverse drug reaction in self-controlled case series studies (베이지안 포아송 모형을 적용한 자기-대조 환자군 연구에서의 약물상호작용 위험도 분석)

  • Lee, Eunchae;Hwang, Beom Seuk
    • The Korean Journal of Applied Statistics
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    • v.33 no.2
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    • pp.203-213
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    • 2020
  • The self-controlled case series (SCCS) study measures the relative risk of exposure to exposure period by setting the non-exposure period of the patient as the control period without a separate control group. This method minimizes the bias that occurs when selecting a control group and is often used to measure the risk of adverse events after taking a drug. This study used SCCS to examine the increased risk of side effects when two or more drugs are used in combination. A conditional Poisson model is assumed and analyzed for drug interaction between the narcotic analgesic, tramadol and multi-frequency combination drugs. Bayesian inference is used to solve the overfitting problem of MLE and the normal or Laplace prior distributions are used to measure the sensitivity of the prior distribution.

Design of an Analog Array using Enhancement of Electric Field on Floating Gate MOSFETs (부유게이트에 지역전계강화 효과를 이용한 아날로그 어레이 설계)

  • Chai, Yong-Yoong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.8
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    • pp.1227-1234
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    • 2013
  • An analog array with a 1.2 double poly floating gate transistor has been developed with a standard CMOS fabrication process. The programming of each cell by means of an efficient control circuit eliminates the unnecessary erasing operation which has been widely used in conventional analog memories. It is seen that the path of the signal for both the programming and the reading is almost exactly the same since just one comparator supports both operations. It helps to eliminate the effects of the amplifier input-offset voltage problem on the output voltage for the read operation. In the array, there is no pass transistor isolating a cell of interest from the adjacent cells in the array. Instead of the extra transistors, one extra bias voltage, Vmid, is employed. The experimental results from the memory shows that the resolution of the memory is equivalent to the information content of at least six digital cells. Programming/erasing of each cell is achieved with no detectable disturbance of adjacent cells. Finally, the unique shape of the injector structure in a EEPROM is adopted as a cell of analog array. It reduces the programming voltage below the transistor breakdown voltage without any special fabrication process.

A Study on the Legality of Arb-Med in China (중국 중재조정의 적법성에 관한 연구)

  • LI, Jing-Hua;SEO, Kyeong
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.69
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    • pp.523-541
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    • 2016
  • According to Chinese Arbitration Law, combination of mediation with arbitration means that in the process of arbitration, arbitrator may conduct mediation proceedings for the case they are handling, provided both parties agree to do so. If mediation succeeds and the parties reach a settlement agreement, the arbitrators may render a consent award or a written mediation statement in accordance with the contents of the settlement agreement. If mediation fails, the arbitration proceedings will be resumed until the case is concluded by making of an arbitral award. There is no formal name of this system in China, it is called "combination of mediation with arbitration", "mediation in arbitration process" or "arbitration-mediation", the author of this thesis select "arbitration-mediation" and make it simply as "Arb-Med". This thesis concentrates on three issues that arbitrators and the parties have to clarify and pay attention to once they choose to use Arb-Med. The first part is about the 'waivable problems', include waive the right to challenge a arbitrator who act as a mediator at the same time with parties' approval, as well as the question about the waiver of the arbitrator's duty to disclose confidential information obtained during mediation. The second part is 'public policy in Arb-Med', introduces the concept of public policy, the bias may arise the complaint about public policy, and the due procedure problem. And the last part is about the award deals with a difference not contemplated by or not falling within the terms of the submission to arbitration, or it contains decisions on matters beyond the scope of the submission to arbitration, especially about the award including some contents which has relation to third party's interests.

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Accuracy Verification of the SBAS Tropospheric Delay Correction Model for the Korean Region (한반도 지역 SBAS 대류층 지연 보정 모델의 정확도 검증)

  • Kim, Dong-uk;Han, Deok-hwa;Kee, Chang-don;Lee, Chul-soo;Lee, Choong-hee
    • Journal of Advanced Navigation Technology
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    • v.20 no.1
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    • pp.23-28
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    • 2016
  • In this paper, we verified accuracy of the satellite based augmentation system (SBAS) tropospheric delay correction model for the Korean region. We employed the precise data of the tropospheric zenith path delay (ZPD) which is provided by the international GNSS service (IGS). In addition, we compared the verification results with that of the Saastamoinen model and the Hopfield model. Consequently, the bias residual error of the SBAS tropospheric delay correction model is about 50 mm, whereas the Saastamoinen model and the Hopfield model are more accurate. This residual error by the tropospheric delay model can affect the SBAS user position accuracy, but there is no problem in SBAS accuracy requirement. If we modified the meteorological parameters for SBAS tropospheric model to appropriate in Korean weather environment, we can provide better SBAS service to the Korean user.

Nucleation and growth mechanism of nitride films deposited on glass by unbalanced magnetron sputtering

  • Jung, Min J.;Nam, Kyung H.;Han, Jeon G.
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2001.06a
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    • pp.14-14
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    • 2001
  • Nitride films such as TiN, CrN etc. deposited on glass by PVD processes have been developed for many industrial applications. These nitride films deposited on glass were widely used for not only decorative and optical coatings but also wear and corrosion resistance coatings employed as dies and molds made of glass for the example of lens forming molds. However, the major problem of nitride coatings on glass by PVD process is non-uniform film owing to pin-hole and micro crack. It is estimated that nonuniform coating is influenced by a different surface energy between metal nitrides and glass due to binding states. In this work, therefore, for the evaluation of nucleation and growth mechanism of nitride films on glass TiN and CrN film were synthesized on glass with various nitrogen partial pressure by unbalanced magnetron sputtering. Prior to deposition, for the examination of relationship between surface energy and film microstructure plasma pre-treatment process was carried out with various argon to hydrogen flow rate and substrate bias voltage, duty cycle and frequency by using pulsed DC power supply. Surface energy owing to the different plasma pre-treatment was calculated by the measurement of wetting angle and surface conditions of glass were investigated by X-ray Photoelectron Spectroscopy(XPS) and Atomic Force Microscope(AFM). The microstructure change of nitride films on glass with increase of film thickness were analyzed by X-Ray Diffraction(XRD) and Scanning Electron Microscopy(SEM).

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Measurements of Correct Operation of a HTS 4-bit Shift Register Circuit (4-비트 고온초전도 Shift Register 회로의 동작 측정)

  • Park, Jong-Hyeog;Kim, Young-Hwan;Kang, Joon-Hee;Hahn, Taek-Sang;Kim, Chang-Hoon;Lee, Jong-Min;Choi, Sang-Sam
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.102-106
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    • 1999
  • We have designed and fabricated a four-bit shift register circuit using YBCO bicrystal junctions and experimentally tested its operations by a computer-controlled digital measurement set-up. Laser ablated YBCO thin films with clean surface were used in this work. The circuit consists of the shift register and two read SQUIDs placed next to each sides of the shift register. The SQUIDs were inductively coupled to the nearby shift register stages. A probe equipped with high speed coax lines were used in this experiment. The major obstacle in testing the circuit was the interference between the read SQUIDs and we solved the problem by finding the correct operation points of the SQUIDs from the simultaneously measured modulation curves. Loaded Data("1" or "0") were successfully shifted from a stage to the next one by a controlled current pulse injected to the bias lines located between the stages and the data shifts were correctly monitored by the read SQUIDs

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Analysis of electron mobility in LDD region of NMOSFET (NMOSFET에서 LDD 영역의 전자 이동도 해석)

  • 이상기;황현상;안재경;정주영;어영선;권오경;이창효
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.10
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    • pp.123-129
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    • 1996
  • LDD structure is widely accepted in fabricating short channel MOSFETs due to reduced short channel effect originated form lower drain edge electric field. However, modeling of the LDD device is troublesome because the analysis methods of LDD region known are either too complicated or inaccurate. To solve the problem, this paper presents a nonlinear resistance model for the LDD region based on teh fact that the electron mobility changes with positive gate bias because accumulation layer of electrons is formed at the surface of the LDD region. To prove the usefulness of the model, single source/drain and LDD nMOSFETs were fabricated with 0.35$\mu$m CMOS technolgoy. For the fabricated devices we have measured I$_{ds}$-V$_{gs}$ characteristics and compare them to the modeling resutls. First of all, we calculated channel and LDD region mobility from I$_{ds}$-V$_{gs}$ characteristics of 1050$\AA$ sidewall, 5$\mu$m channel length LDD NMOSFET. Then we MOSFET and found good agreement with experiments. Next, we use calculated channel and LDD region mobility to model I$_{ds}$-V$_{gs}$ characteristics of LDD mMOSFET with 1400 and 1750$\AA$ sidewall and 5$\mu$m channel length and obtained good agreement with experiment. The single source/drain device characteristic modeling results indicates that the cahnnel mobility obtained form our model in LDD device is accurate. In the meantime, we found that the LDD region mobility is governed by phonon and surface roughness scattering from electric field dependence of the mobility. The proposed model is useful in device and circuit simulation because it can model LDD device successfully even though it is mathematically simple.

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Study on the Shortest Path by the energy function in Hopfield neworks (홉필드 네트웍에서 에너지 함수를 이용한 최적 경로 탐색에 관한 연구)

  • Ko, Young-Hoon;Kim, Yoon-Sang
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.10 no.5
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    • pp.215-221
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    • 2010
  • Hopfield networks have been proposed as a new computational tool for finding the shortest path of networks. Zhang and Ali studied the method of finding shortest path by expended neurons of Hopfield networks. Ali Algorithm is well known as the tool with the neurons of branch numbers. Where a network grows bigger, it needs much more time to solve the problem by Ali algorithm. This paper modifies the method to find the synapse matrix and the input bias vector. And it includes the eSPN algorithm after proper iterations of the Hopfield network. The proposed method is a tow-stage method and it is more efficient to find the shortest path.The proposed method is verified by three sample networks. And it could be more applicable then Ali algorithm because it's fast and easy. When the cost of brach is changed, the proposed method works properly. Therefore dynamic cost-varing networks could be used by the proposed method.