• Journal of the Korean Data and Information Science Society
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• 제15권2호
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• pp.331-337
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• 2004

In the analysis of massive volume data, a neural network model is a useful tool. To implement the Neural network model, it is important to select initial value. Since the initial values are generally used as random value in the neural network, the convergent performance and the prediction rate of model are not stable. To overcome the drawback a possible method use samples randomly selected from the whole data set. That is, coefficients estimated by logistic regression based on the samples are the initial values.

• Communications for Statistical Applications and Methods
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• 제7권1호
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• pp.65-86
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• 2000

The estimates from an EM when it is applied to a large causal model of 10 or more categorical variables are often subject to the initial values for the estimates. This phenomenon becomes more serious as the model structure becomes more serious as the model structure becomes more complicated involving more variables. In this regard Wu(1983) recommends among others that EMs are implemented several times with different sets of initial values to obtain more appropriate estimates. in this paper a new approach for initial values is proposed. The main idea is that we use initials that are calibrated to data. A simulation result strongly indicates that the calibrated initials give rise to the estimates that are far closer to the true values than the initials that are not calibrated.

• Nuclear Engineering and Technology
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• 제55권12호
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• pp.4607-4616
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• 2023

We implement machine learning regression models to predict peak pressures of primary and secondary systems, a major safety concern in Loss Of Condenser Vacuum (LOCV) accident. We selected the Multi-dimensional Analysis of Reactor Safety-KINS standard (MARS-KS) code to analyze the LOCV accident, and the reference plant is the Korean Optimized Power Reactor 1000MWe (OPR1000). eXtreme Gradient Boosting (XGBoost) is selected as a machine learning tool. The MARS-KS code is used to generate LOCV accident data and the data is applied to train the machine learning model. Hyperparameter optimization is performed using a simulated annealing. The randomly generated combination of initial conditions within the operating range is put into the input of the XGBoost model to predict the peak pressure. These initial conditions that cause peak pressure with MARS-KS generate the results. After such a process, the error between the predicted value and the code output is calculated. Uncertainty about the machine learning model is also calculated to verify the model accuracy. The machine learning model presented in this paper successfully identifies a combination of initial conditions that produce a more conservative peak pressure than the values calculated with existing methodologies.

• International Journal of Computer Science & Network Security
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• 제22권1호
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• pp.167-174
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• 2022

In metaheuristic algorithms such as Genetic Algorithm (GA), initial population has a significant impact as it affects the time such algorithm takes to obtain an optimal solution to the given problem. In addition, it may influence the quality of the solution obtained. In the machine learning field, feature selection is an important process to attaining a good performance model; Genetic algorithm has been utilized for this purpose by scientists. However, the characteristics of Genetic algorithm, namely random initial population generation from a vector of feature elements, may influence solution and execution time. In this paper, the use of a statistical algorithm has been introduced (Chi2) for feature relevant checks where p-values of conditional independence were considered. Features with low p-values were discarded and subject relevant subset of features to Genetic Algorithm. This is to gain a level of certainty of the fitness of features randomly selected. An ensembled-based learning model for Hepatitis has been developed for Hepatitis C stage classification. 1385 samples were used using Egyptian-dataset obtained from UCI repository. The comparative evaluation confirms decreased in execution time and an increase in model performance accuracy from 56% to 63%.

• 전자공학회논문지
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• 제51권5호
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• pp.44-50
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• 2014

카오스 통신 시스템은 보안성을 향상시키기 위해 적용하는 보안 알고리즘 중에 하나이다. 카오스 신호는 비선형적이며 초기조건에 따라 불규칙하게 생성된다. 또한, 카오스 통신 시스템은 비주기성, 광대역성, 비예측성, 구현의 용이성 등의 특성을 가지고 있다. 그래서 카오스 통신 시스템은 보안성이 우수하고 낮은 도청 확률과 좋은 항재밍 특성을 갖는다. 하지만 BER 성능은 디지털 통신 시스템보다 나쁘게 평가되는데, CDSK 방식의 경우에는 많은 자기 간섭 신호로 인해 BER 성능이 열화된다. 이런 단점을 개선하기 위해, 우리는 이전 연구에서 BER 성능을 향상시킬 수 있는 PDF 경향을 분석하고 이를 통해 카오스 맵을 제안하였다. 그리고 제안한 카오스 맵은 Boss map이라고 정의하였다. 일반적으로, 카오스 맵의 초기값과 매개변수, 확산인자에 따라 BER 성능이 달라진다. 따라서, 본 논문에서는 BER 성능을 향상시킬 수 있는 PDF 경향을 소개하고, Boss map에 대해 설명한다. 또한, Boss map의 초기값과 매개변수, 확산인자에 따른 BER 성능을 평가하여 Boss map의 특성을 분석한다. 그 결과, Boss map은 유사한 BER 성능을 유지하면서 초기값을 0부터 1.2까지 선택할 수 있으며, 매개변수 알파값은 2.5일 때 가장 좋은 BER 성능을 보인다. 또한, 확산인자 값이 50일 때 가장 좋은 BER 성능을 가진다.

• 한국인터넷방송통신학회논문지
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• 제24권1호
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• pp.83-88
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• 2024

본 연구에서는 Railroad surface 데이터를 활용하여 Semi-Supervised learning방식으로 railroad surface의 defect를 검출해내는 방안을 제안한다. Resnet50에 ImageNet으로 pretrained된 모델을 이용한다. Label이 없는 데이터에서 무작위로 데이터를 선정, 선정한 데이터에 label을 부여한 뒤 이 데이터로 모델을 학습시킨다. 학습된 모델을 이용하여 나머지 데이터의 결과값을 예측한 후, 그 예측값이 일정한 threshold보다 큰 것을 골라내고, threshold보다 큰 값들을 값이 큰 순서대로 정렬하여, 일정한 크기만큼 training data에 추가한다. 이 때, 각 class에 속할 확률이 높은 쪽으로 pseudo-labeling을 수행한다. 초기에 label이 부여된 데이터 개수에 따른 전체적인 class 분류 성능을 확인하는 실험 또한 진행하였고, 전체 training data대비 10% 미만의 labeled data로 최대 98%의 정확도를 얻는 성능을 보였다.

• Asian-Australasian Journal of Animal Sciences
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• 제33권10호
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• pp.1624-1632
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• 2020

Objective: A total of three hundred unsexed ducks were utilized to estimate net energy requirements of maintenance (NE_m) and weight gain (NE_g) for 2 to 3-week-old Cherry Valley ducks and to establish a model equation to predict NE requirements using the factorial method. Methods: To determine the apparent metabolizable energy (AME) of the diet, fifty 7-day-old ducks at approximately equal body weights (BWs) were randomly assigned into five groups that were fed at different levels (ad libitum, 85%, 75%, 65%, and 55% of ad libitum intake), and the endogenous acid-insoluble ash as indigestible marker. The two hundred and fifty 7-day-old ducks were used for a comparative slaughter experiment. At the beginning of the experiment, ten ducks were sacrificed to determine the initial body composition and energy content. The remaining ducks were randomly assigned into five groups (same as metabolic experiment). Ducks of the ad libitum group were slaughtered at 14 and 21-day-old. At the end of the experiment, two ducks were selected from each replicate and slaughtered to determine the body composition and energy content. Results: The results of the metabolizable experiment showed AME values of 13.43 to 13.77 MJ/kg for ducks at different feed intakes. The results of the comparative slaughter experiment showed the NE_m value for 2 to 3-week-old Cherry Valley ducks was 549.54 kJ/kg of BW^0.75/d, and the NE_g value was 10.41 kJ/g. The deposition efficiency values of fat (K_f) and crude protein (K_p) were 0.96 and 0.60, respectively, and the values of efficiency of energy utilization (K_g) and maintenance efficiency (K_m) were 0.75 and 0.88, respectively. Conclusion: The equation for the prediction of NE requirements for 2 to 3-week-old Cherry Valley ducks was the following: NE = 549.54 BW^0.75+10.41 ΔW, where ΔW is the weight gain (g).

• 대한수의학회지
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• 제27권2호
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• pp.321-330
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• 1987

In the endemic area of bovine piroplasmosis in Chonbuk Province, total of 486 heads of Holstein cow selected from 14 farms randomly were examined the infection status of piroplasma and their blood values. The results obtained were summarized as follows: 1. The etiological agent was only Theileria sergenti and none of the Babesia sp. infection. 2. All of the 486 heads of examined cow were infected with Theileria sergenti (100%). 3. In the initial examination of 11 farms in early summer, the means of blood values were as follows; RBC:$526{\pm}84(10^4/mm^3$), Ht:$27.9{\pm}2.8%$, SP:$7.5{\pm}0.6g/dl$, WBC: $11586{\pm}354/mm^3$, and Fibrinogen: $578.5{\pm}164.1mg/dl$. 4. In the second examinations in slimmer season, the blood values of examined cows had little varieties. But in the winter season, cows housed in the barn, the blood values were greatly increased; RBC: $601{\pm}77(10^4/mm^3)$, (F-value: 37.186**), Ht: $30.5{\pm}1.3%$(F-value: 15.626**) Hb: $12.2{\pm}1.3g/dl$(F-value: 5.899**), SP: $7.4{\pm}0.6g/dl$(F-value: 5.05**). 5. To determine the piroplasma infection in the many herds of cow, the measurement of Ht, Hb, and SP values etc. were more effective and helpful to find the weak cow because the examined process are not only to be easily carry out many samples but also to be done very simple and rapidly. 6. The indications of therapeutic standard values were stablished as follows; the less than 20% in the Ht value, below the 10g/dl in the Hb value, and less than 6g/dl in SP value. When the one among the therapeutic standard values, Ht, Hb, and SP was below the therapeutic standard value, the cow was treated with nutriments. When more than two among them were below the therapeutic standard, the cow was treated with Berenil, at once. In this way, there was no one head which represented clinical signs of piroplasmosis among 486 heads of cow at 14 farms during the year of 1986. 7. In a Korean native cattle infected with Thieleria sergenti seriously, the recovery of blood values was very prolonged by the treatment of Berenil only. But by the transfusion of 300ml blood collected from normal cow, the blood values were recovered rapidly.

• Asian-Australasian Journal of Animal Sciences
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• 제23권12호
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• pp.1645-1656
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• 2010

This study was conducted to investigate the effects of strain on broiler performance, and age at slaughter and postchilling (PC) aging time on meat quality traits. A total of 500 one-day-old chicks (250 Hubbard classic and 250 Lohman) were reared under commercial conditions. Half of the broiler birds from each strain were slaughtered at 32 days and the other half at 42 days old. At each processing day, 168 carcasses were randomly selected (84 Hubbard and 84 Lohman) and divided into groups of 28 carcasses within each strain, and aged for 0, 4 and 24 h after chilling. Average weekly body weight was comparable between strains. Feed conversion ratio was higher (p<0.05) for the Hubbard strain during the second and third week of age. Initial carcass pH was significantly (p<0.05) affected by age where younger birds (32-d-old) had lower pH values than older (41-d-old) birds. Breast temperature was higher (p<0.001) for Lohman than Hubbard at 0, 2 and 4 h of PC. Younger birds had a lower breast temperature (p<0.001) at all measured times of PC. Thaw loss, cook loss and water holding capacity were not significantly affected by strain, age or aging time. Lohman strain had more tender meat (p<0.05) than Hubbard strain, and tenderness was improved with the increase of broiler age and aging time. Meats from Hubbard were lighter and less red than those from Lohman strain where younger birds had darker color. In conclusion, strain, age at slaughter and PC aging duration are critical to breast meat quality characteristics, and 4 h of aging are required before deboning in order to obtain more tender fillets.

• Journal of Periodontal and Implant Science
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• 제24권1호
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• pp.120-130
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• 1994

The purpose of the present investigation was to compare the effectiveness of porous hydroxyapatite (PHA) and coralline based porous calcium carbonate(PCC) as implant materials in human periodontal osseous defects. 10 adult patients having periodontitis and 2 similar angular osseous defects ${\ge}$5mm as verified by radiographic analysis and clinical probing depth ${\ge}$4mm were selected. The measurements were recorded just before surgery and after 6 month. Clinical parameters used in this study included gingival recession, pocket depth, probing attachment level, Sulcus Bleeding Index, Plaque Index, tooth mobility and bone defect depth measurements. After initial therapy, patients were treated with mucoperiosteal flap surgery. The contralateral bony defects in each patient randomly assigned to either bone graft material, one with PHA(Interpore 200) and the other with coralline based calcium carbonate(Biocoral). After 6 month both groups showed statistically significant reduction of pocket depth, Sulcus Bleeding Index, Plaque Index and significant improvement in probing attachment level. No statistically significant differences were found between the groups. There were 3.0mm or 68% of bone repair with PHA and 3.1mm, 61% with PCC. These values were likewise not significantly different. The data and clinical impression strongly suggest that both PHA and PCC are alloplastic implants with clinically apparent acceptance by the soft and hard tissue and that they can be used as bone graft materials successfully.