• 제목/요약/키워드: bias effect

검색결과 1,465건 처리시간 0.03초

Al2O3 High Dense Single Layer Gas Barrier by Neutral Beam Assisted Sputtering (NBAS) Process

  • 장윤성;홍문표
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.157-157
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    • 2015
  • Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}g/m^2day$. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2day$) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study NBAS process was introduced to deposit enhanced film density single gas barrier layer with a low WVTR. Fig. 1. shows a schematic illustration of the NBAS apparatus. The NBAS process was used for the $Al_2O_3$ nano-crystal structure films deposition, as shown in Fig. 1. The NBAS system is based on the conventional RF magnetron sputtering and it has the electron cyclotron resonance (ECR) plasma source and metal reflector. $Ar^+$ ion in the ECR plasma can be accelerated into the plasma sheath between the plasma and metal reflector, which are then neutralized mainly by Auger neutralization. The neutral beam energy is controlled by the metal reflector bias. The controllable neutral beam energy can continuously change crystalline structures from an amorphous phase to nanocrystal phase of various grain sizes. The $Al_2O_3$ films can be high film density by controllable Auger neutral beam energy. we developed $Al_2O_3$ high dense barrier layer using NBAS process. We can verified that NBAS process effect can lead to formation of high density nano-crystal structure barrier layer. As a result, Fig. 2. shows that the NBAS processed $Al_2O_3$ high dense barrier layer shows excellent WVTR property as a under $2{\times}10^{-5}g/m^2day$ in the single barrier layer of 100nm thickness. Therefore, the NBAS processed $Al_2O_3$ high dense barrier layer is very suitable in the high efficiency OLED application.

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수산물의 유통단계별 가격간 장기균형관계와 인과성 분석 -부산지역의 갈치, 오징어를 중심으로- (A Study on the Long-run Equilibrium Relationship and Causality between the Prices of Fisheries Products at Different Levels of Distribution -Focused on Hairtail and Squid in Pusan-)

  • 강석규;이광진
    • 수산경영론집
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    • 제29권2호
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    • pp.77-96
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    • 1998
  • Fisheries products in Korea generally go through three markets, namely the wholesale market at production site (Market A), the wholesale market at consumption site (Market B), and the retail market (Market C), from producers to end consumers. As the products move from Market A through Market B to Market C, the marginal gap of prices asked in these markets demonstrates an apparent relationship. The producers, middlemen, consumers, and governmental departments concerned may influence the marketing prices of fisheries products. This study employing the cointegration theory tries to investigate whether causality of the price-setting among these markets exists and, if any, what it is. The authors have focused their attention on fisheries markets in Pusan, analyzing the long-run equilibrium relationship and causality between the prices of hairtail and squid among markets at different levels. Data used in this study cover the period f개m August 1984 to December 1997 fer hairtail, and the period from May 1989 to December 1997 for squid. The main findings of the study may be summarized as follows: First, regardless of the price time-series of hairtail and squid in individual market, the first difference is necessary fur satisfying the stationary conditions since each time-series is a first integration. This means homogeneous integration of time-series, which is a requirement of the long-run equilibrium of prices at different markets, is satisfied. Second, the study of the long-run equilibrium relationship between the prices at Market A and Market B shows that a long-run equilibrium relationship does exist for selling prices of the two species at Market A and Market B. Third, the ECM (error correction model ) used here to describe the long- and short-run dynamics of price change demonstrates that, in the case of squid, the price change in Market A will lead to a corresponding price change in Market B in the long-run period. In the short-run, however, the price at Market H is not only influenced by the price change in Market A but influence the price at Market A as well, that is, the Prices between Market A and Market B have a feedback effect. It should be stressed that the limitation in data collection, which cover only two species of hairtail and squid, is likely to cause a sampling bias. Nonetheless, we may conclude that a dynamic relation in the formation of prices does exist in view of the transaction amount of species at different markets. It is believed that the conclusion drawn from this study would not only contribute to a long-lasted debate on the direction of causality of price-setting among academic circle and fishing community, but would provide a useful standard for the policy makers in charge of the price-setting of fisheries products as well.

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기계적으로 체결된 복합재료 평판에서 다양한 인자의 영향에 따른 원공 주위의 응력분포 (Effect of Various Parameters on Stress Distribution around Holes in Mechanically Fastened Composite Laminates)

  • 최재민;전흥재;변준형
    • Composites Research
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    • 제18권6호
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    • pp.9-18
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    • 2005
  • 복합재료가 항공기 구조물 및 기계부품 등에 폭 넓게 적용됨에 따라, 복합재료 구조물에서 가장 취약한 복합재료 체결부의 설계는 매우 중요한 연구 분야로 대두되고 있다. 본 논문에서는 기계적으로 체결이 된 단일 및 다중 핀 하중을 받는 복합재료 평판에서 응력분포에 대한 해석적인 연구를 수행하였다. 또한, 기계적체결부인 핀과 구멍간에서 접촉 문제를 다루기 위하여 접촉응력해석을 이용한 유한요소 모델이 사용되었으며, 응력분포를 정량적으로 비교하기 위하여 무차원화한 응력집중계수를 이용하였다. 단일 핀 하중을 받는 경우에 대하여 적층순서, 원공의 지름에 대한 평판 폭의 비 (W/D ratio), 원공의 지름에 대한 끝단에서 원공까지의 길이의 비 (En ratio), 마찰계수, 와셔의 조임력 등에 대한 영향을 알아보았으며, 다중 핀 하중을 받는 경우에 응력집중계수를 이용하여 핀의 개수, 피치, 열의 개수, 열 간격 및 원공의 배치형상의 영향에 대하여 알아보았다. 단일 핀 하중을 받는 경우에 대한 결과로부터, DBLT (Double-Bias-Longitudinal Transverse) 복합재료 평판에서 응력이 가장 민감하게 나타나는 것을 알 수 있었고, 원공의 지름에 대한 평판 폭의 비와끝단에서 원공까지의 길이의 비에 따른 응력의 변화가 민감하게 나타나는 것을 확인할 수 있었다. 또한, 다중핀 하중을 받는 경우에 대한 응력해석의 결과로부터, 원공이 2열로 배치된 복합재료 평판에서 응력집중현상이 가장 적게 일어나는 것을 확인하였다. 이러한 해석을 통하여, 체결부에서 나타나는 응력분포로부터 복합재료 평판에서의 파손형태를 예측할 수 있다.

ADVANTAGES OF USING ARTIFICIAL NEURAL NETWORKS CALIBRATION TECHNIQUES TO NEAR-INFRARED AGRICULTURAL DATA

  • Buchmann, Nils-Bo;Ian A.Cowe
    • 한국근적외분광분석학회:학술대회논문집
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    • 한국근적외분광분석학회 2001년도 NIR-2001
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    • pp.1032-1032
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    • 2001
  • Artificial Neural Network (ANN) calibration techniques have been used commercially for agricultural applications since the mid-nineties. Global models, based on transmission data from 850 to 1050 nm, are used routinely to measure protein and moisture in wheat and barley and also moisture in triticale, rye, and oats. These models are currently used commercially in approx. 15 countries throughout the world. Results concerning earlier European ANN models are being published elsewhere. Some of the findings from that study will be discussed here. ANN models have also been developed for coarsely ground samples of compound feed and feed ingredients, again measured in transmission mode from 850 to 1050 nm. The performance of models for pig- and poultry feed will be discussed briefly. These models were developed from a very large data set (more than 20,000 records), and cover a very broad range of finished products. The prediction curves are linear over the entire range for protein, fat moisture, fibre, and starch (measured only on poultry feed), and accuracy is in line with the performance of smaller models based on Partial Least Squares (PLS). A simple bias adjustment is sufficient for calibration transfer across instruments. Recently, we have investigated the possible use of ANN for a different type of NIR spectrometer, based on reflectance data from 1100 to 2500 nm. In one study, based on data for protein, fat, and moisture measured on unground compound feed samples, dedicated ANN models for specific product classes (cattle feed, pig feed, broiler feed, and layers feed) gave moderately better Standard Errors of Prediction (SEP) compared to modified PLS (MPLS). However, if the four product classes were combined into one general calibration model, the performance of the ANN model deteriorated only slightly compared to the class-specific models, while the SEP values for the MPLS predictions doubled. Brix value in molasses is a measure of sugar content. Even with a huge dataset, PLS models were not sufficiently accurate for commercial use. In contrast an ANN model based on the same data improved the accuracy considerably and straightened out non-linearity in the prediction plot. The work of Mr. David Funk (GIPSA, U. S. Department of Agriculture) who has studied the influence of various types of spectral distortions on ANN- and PLS models, thereby providing comparative information on the robustness of these models towards instrument differences, will be discussed. This study was based on data from different classes of North American wheat measured in transmission from 850 to 1050 nm. The distortions studied included the effect of absorbance offset pathlength variation, presence of stray light bandwidth, and wavelength stretch and offset (either individually or combined). It was shown that a global ANN model was much less sensitive to most perturbations than class-specific GIPSA PLS calibrations. It is concluded that ANN models based on large data sets offer substantial advantages over PLS models with respect to accuracy, range of materials that can be handled by a single calibration, stability, transferability, and sensitivity to perturbations.

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90 nm CMOS 공정을 이용한 60 GHz WPAN용 저잡음 증폭기와 하향 주파수 혼합기 (60 GHz WPAN LNA and Mixer Using 90 nm CMOS Process)

  • 김봉수;강민수;변우진;김광선;송명선
    • 한국전자파학회논문지
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    • 제20권1호
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    • pp.29-36
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    • 2009
  • 본 논문에서는 60 GHz 대 역에서 동작하는 WPAN용 수신기에 필요한 저잡음 증폭기와 하향 주파수 혼합기를 90 nm CMOS 공정을 이용하여 설계하고 제작한 결과를 보인다. 우선 각 소자에 사용될 트랜지스터의 특성을 추출하기 위해 원하는 바이어스 조건에서 cascode 구조의 S-parameter를 측정했으며, 이 때 사용된 RF 패드를 따로 측정하여 그 영향을 제거함으로써 트랜지스터만의 특성을 찾아내었다. 저잡음 증폭기는 3단의 cascode 구조를 사용했으며, 측정 결과 25 dB 이득과 7 dB 이하의 잡음지수 결과를 얻었다. 그리고 하향 주파수 혼합기는 LO의 입력에 balun을 사용한 balanced 구조로 측정 결과 IF 주파수($8.5{\sim}11.5\;GHz$) 범위내에서 12.5 dB의 변환 손실과 -7 dBm의 입력 PldB을 나타내었다. 제작된 저잡음 증폭기 및 하향 주파수 혼합기의 크기와 소모 전력은 각각 $0.8{\times}0.6\;mm^2$에 43 mW와 $0.85{\times}0.85\;mm^2$에 1.2 mW이다.

태양광도계 자료를 이용한 한반도 내 Himawari-8 관측 AOD 특성 분석 (Analysis of AOD Characteristics Retrieved from Himawari-8 Using Sun Photometer in South Korea)

  • 이기택;유선우;이태영;서명석
    • 대한원격탐사학회지
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    • 제36권3호
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    • pp.425-439
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    • 2020
  • 최근 성능이 크게 개선된 정지궤도 기상위성 Himawari-8, GK2A등이 운용됨에 따라 시공간적으로 보다 고해상도 AOD(Aerosol Optical Depth) 자료의 사용이 가능해졌다. 본 연구에서는 최근 4년간 한반도내 AERONET(Aerosol Robotic Network) 참여 5개 지점(서울대학교, 연세대학교, 한국외국어대학교, 광주과학기술원(GIST), 안면도 기후변화감시센터)의 에어로졸 관측 자료를 이용하여 Himawari-8/AHI(Advanced Himawari Imager) 에어로졸 산출물의 특징과 두 AOD 자료 간에 차이가 발생하는 원인에 대해 분석하였다. 분석결과 위성과 지상관측 AOD는 하늘이 맑을 경우(운량 < 3)에는 지리적 위치에 관계없이 매우 유사하게 나타났다. 하지만 운량이 증가할 경우 위성 관측과 지상관측 AOD의 차이는 지리적 위치에 관계없이 현저하게 증가하였다(편의: 0.05(맑음) → 0.21(전체), 상관계수: 0.74 → 0.64, RMSE: 0.21 → 0.51). 5개 지점 모두에서 운량이 많거나 상대습도가 높을 때 위성이 지상관측에 비해 AOD를 크게 과대 추정하는 것으로 보아 두 AOD 자료 간의 차이는 주로 운량과 상대습도와 관련이 깊은 것으로 판단된다. 하지만 풍속, 가강수량, 구름 하부 높이, 그리고 옹스트롬 지수(Angstrom Exponent)는 두 AOD 자료 간의 차이에 영향을 미치지 않는 것으로 보인다. 본 연구의 결과는 운량이 많을 경우 위성 관측 AOD 자료 사용시 주의가 필요함을 제시한다.

$^{99m}Tc$-HMPAO 뇌혈류 SPECT 영상의 부위별 체적 혈류 평가에 관한 기초 연구 (A Preliminary Quantification of $^{99m}Tc$-HMPAO Brain SPECT Images for Assessment of Volumetric Regional Cerebral Blood Flow)

  • 곽철은;박석건;양형인;최창운;이경한;이동수;정준기;이명철;고창순
    • 대한핵의학회지
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    • 제27권2호
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    • pp.170-174
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    • 1993
  • 뇌혈류 SPECT영상을 사용하여 뇌혈류를 간접적으로 평가하는 방법으로 횡단면 또는 관상면의 단층상을 이용하여 관류 결손 부위의 계수 분포를 평면적으로 조사하는 방법이 주로 사용되어 왔으나, 일반적으로 관류결손 부위의 크기는 다양하며 특히 임의의 형태를 갖는 관류 결손을 포함하는 영상에서는 평면 분석에 의한 결과는 많은 오차를 나타낼 수 있다. 따라서 본 연구는 체적 분석에 의한 평가 방법을 제안하고자 하였으며, 기초연구로서 동일한 뇌혈류 SPECT 영상에 대하여 평면 분석과 체적 분석 방법을 적용하여 비교하므로서 체적 분석 방법의 안정도와 정확도를 검토하였다. 평면 분석 방법에서는 관류 결손 부위의 크기와 형상에 따라 뇌혈류평가 지표인 계수 분포의 변화가 관찰되었으며, 합산에 사용된 단층상의 수에 따라 체적 분석과 상이한 결과를 보였다. 또한 평면 분석은 횡단면을 사용하는 경우와 관상면을 사용하는 경우 각각에서도 상이한 결과를 보여 체적 분석 방법이 뇌혈류 평가지표로서 신뢰도 높은 결과를 산출할 수 있음을 알았다.

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불면장애에 대한 혈부축어탕의 체계적 문헌 고찰 및 메타분석 연구 (Herbal Medicine (Hyeolbuchukeo-tang, Xuefu Zhuyu Decoction) for Insomnia Disorder: A Systematic Review and Meta-analysis of Randomized Controlled Trials)

  • 김동희;이승환;임정화;김상호;이상협;김보경
    • 동의신경정신과학회지
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    • 제28권4호
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    • pp.319-332
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    • 2017
  • Objectives: The present study aimed to provide clinical evidence on the effect of herbal medicine, Hyeolbuchukeo-tang or Xuefu Zhuyu decoction for the treatment of primary insomnia using a systematic review and meta-analysis of randomized controlled trials (RCTs). Methods: This study included RCTs that verified the effects of Hyeolbuchukeo-tang or Xuefu Zhuyu decoction for the treatment of primary insomnia. Literature searches of English, Chinese and Korean databases were performed, and the selected literature was assessed for investigating the risk of bias. Results: The analysis included 10 RCTs. The Chinese Classification of Mental Disorders-3 was most frequently used to define the diagnostic criteria for Hyeolbuchukeo-tang or Xuefu Zhuyu decoction intervention in patients with primary insomnia. The effective rate was the most commonly used outcome measure. A meta-analysis revealed that the effective rate, the Pittsburgh Sleep Quality Index, and the Athens Insomnia Scale in the Modified Xuefu Zhuyu decoction (MXZD) group were higher compared to Western Medicine (WM) group (RR: 1.17, 95% Cl: 1.08 to 1.26, p<0.0001, $I^2$=0/MD: -1.29, 95% Cl: -2.09 to -0.49, p=0.002, $I^2$=0%/MD: -0.99, 95% Cl: -1.81 to -0.18, p=0.02, $I^2$=15%). The effective rate of the MXZD+WM group was significantly different compared to the WM group (RR: 1.28, 95% Cl: 1.11 to 1.47, p=0.0006, $I^2$=2%). The included RCTs were of relatively poor quality and had small sample sizes. Conclusions: Treatment with Hyeolbuchukeo-tang or Xuefu Zhuyu decoction was found to be effective in treating primary insomnia. However, the included RCTs were of relatively poor quality and had small sample sizes. It is hypothesized that this study could serve as a foundation for further clinical studies on the development of diagnosis and treatment methods for primary insomnia based on Korean medicine.

초등학생들의 음주기대에 관한 연구 (A Study on Alcohol Expectancy of Elementary Schoolchild)

  • 임미숙;박영수
    • 한국학교ㆍ지역보건교육학회지
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    • 제3권
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    • pp.15-33
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    • 2002
  • Researchers' common findings is that there are positive or negative effect of alcohol expectancy on drinking behavior. Therefore we would effectively prevent troublesome drinking of the youth and university students by inquiring and controlling critical factors affecting alcohol expectancy. The purposes of this thesis are, first, to empirically test factors affecting the alcohol expectancy level of elementary schoolchild(potential drinker).; second, to suggest the necessity for development of pre-alcohol prevention programs. On the basis of previous research, eighteen factors included in four categories(general characters, environmental characters, alcohol knowledge, drinking experience) affecting alcohol expectancy level were found out. 623 subjects used in this study were drawn from 8 elementary schools in Daegu, Korea. The empirical results suggested that the alcohol expectancy level of elementary schoolchildren was negative in general. And it was proved that 9 factors were significantly correlated with alcohol expectancy level. To put it concretely(see Fig.), (1) It was proved that schoolchildren with bad environment(live in oneself, displeased drinking feeling) rather than good environment(live with parents, nice drinking feeling) for drinking had more negative alcohol expectancy. (2) Korean traditional culture that partakes of sacrificial food and drink have an influence on the first drinking of most elementary schoolchildren. And it was proved that schoolchildren with this drinking experience rather than any other motives had less negative alcohol expectancy. (3) It was proved that schoolchildren adapting themselves rather than being difficult in school life had more negative alcohol expectancy. And the more knowledge about alcohol or drinking schoolchildren had, the more they had negative alcohol expectancy (4) It was proved that schoolchildren having drinking experience or drinking at present rather than having no drinking experience or not-drinking at present had less negative alcohol expectancy. (5) It was proved that schoolchildren having strong drinking intention rather than having weak or no drinking intention in the future had more positive alcohol expectancy. Based on previous results, guideline for development of pre-alcohol prevention programs can be represented: discriminated programs development on educatee, drinking education programs development increasing the power of self-control about alcohol and drinking, social education or continuing education programs development on drinking, open preschool education to substantially prevent drinking or alcoholism etc. The findings, however, should be interpreted with caution, because this study has several limitations in measurement and sampling as follows. First, selection bias because of limited selection of sampling. It is because the subjects are drawn from only 8 elementary schools in Daegu. Second, less refined measurement ; Therefore, it is necessary to develop more detailed measures on alcohol knowledge, alcohol expectancy level especially. Further researches should be suggested and encouraged with more refined methodologies.

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Predictive Modeling for the Growth of Listeria monocytogenes as a Function of Temperature, NaCl, and pH

  • PARK SHIN YOUNG;CHOI JIN-WON;YEON JIHYE;LEE MIN JEONG;CHUNG DUCK HWA;KIM MIN-GON;LEE KYU-HO;KIM KEUN-SUNG;LEE DONG-HA;BAHK GYUNG-JIN;BAE DONG-HO;KIM KWANG-YUP;KIM CHEOL-HO
    • Journal of Microbiology and Biotechnology
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    • 제15권6호
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    • pp.1323-1329
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    • 2005
  • A mathematical model was developed for predicting the growth kinetics of Listeria monocytogenes in tryptic soy broth (TSB) as a function of combined effects of temperature, pH, and NaCl. The TSB containing four different concentrations of NaCl (2, 4, 5, and $10\%$) was initially adjusted to six different pH levels (pH 5, 6, 7, 8, 9, and 10) and incubated at 4, 10, 25, or 37$^{circ}C$. In all experimental variables, the primary growth curves were well fitted ($r^{2}$=0.982 to 0.998) to a Gompertz equation to obtain the lag time (LT) and specific growth rate (SGR). Surface response models were identified as appropriate secondary models for LT and SGR on the basis of coefficient determination ($r^{2}$=0.907 for LT, 0.964 for SGR), mean square error (MSE=3.389 for LT, 0.018 for SGR), bias factor ($B_{1}$B,=0.706 for LT, 0.836 for SGR), and accuracy factor ($A_{f}$=1.567 for LT, 1.213 for SGR). Therefore, the developed secondary model proved reliable predictions of the combined effect of temperature, NaCl, and pH on both LT and SGR for L. monocytogenes in TSB.