• Communications for Statistical Applications and Methods
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• 제20권6호
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• pp.455-466
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• 2013

In nested case-control studies, the most common way to make inference under a proportional hazards model is the conditional logistic approach of Thomas (1977). Inclusion probability methods are more efficient than the conditional logistic approach of Thomas; however, the epidemiology research community has not accepted the methods as a replacement of the Thomas' method. This paper promotes the inverse probability weighting method originally proposed by Samuelsen (1997) in combination with an approximate jackknife standard error that can be easily computed using existing software. Simulation studies demonstrate that this approach yields valid type 1 errors and greater powers than the conditional logistic approach in nested case-control designs across various sample sizes and magnitudes of the hazard ratios. A generalization of the method is also made to incorporate additional matching and the stratified Cox model. The proposed method is illustrated with data from a cohort of children with Wilm's tumor to study the association between histological signatures and relapses.

• International Journal of Computer Science & Network Security
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• 제22권8호
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• pp.304-322
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• 2022

This study investigated a case of a gifted Saudi student, X, who was early detected through Mawhiba (The Saudi Institution of Gifted) when he was eight years old. Then, the journey continued until he became a Tamayuz member and received a scholarship in 2022 to pursue his bachelor's at one of the prestige, high-ranking universities in the USA to study Mathematics and Economics. Lack of information about the status of Saudi verbal gifted maked X case a model to explore the roles of Mawhiba's programs in supporting Saudi verbal giftedness in general and particularly in learning the English language, plus seeking the opportunities Mawhiba provided for Saudi verbal gifted to enrich their giftedness in the English language through providing extended social networking and finally stating the sample's perspective about the opportunities and services Mawhiba provided him. The three core instruments to accumulate elaboration and interpret qualitative and quantitative data were academic records, writing samples, family observation, and a written interview.

• 한국식품과학회지
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• 제32권4호
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• pp.881-888
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• 2000

본 연구에서는 냉동건조에 의한 생균수 감소를 줄이기 위하여 첨가된 냉동건조보호제(Freeze Drying Protectant : FDP)가 우유 또는 난백분말로 만든 젖산균 발효식품의 품질(관능적 특성, 휘발성 향기 성분, 물성)에 미치는 영향을 조사하였다. 우유시료에는 0.2%의 Tween 80과 1%의 ascorbate를 각각 첨가하고, 난백분말시료에는 3%의 raffinose와 1%의 ascorbate를 각각 첨가하여 다음과 같은 결과를 얻었다. (1) 냉동건조시키지 않은 시료의 관능적 특성은 표준시료(우유시료)와 비교하여 ascorbate 첨가 우유시료는 관능적 특성이 다소 우수하였으나, 난백분말시료 또는 FDP 첨가 난백분말시료는 관능적 특성이 다소 저조하였다. (2) 냉동건조 후 복원시킨 시료의 관능성은 표준시료(우유시료)와 다른 5종의 시료 사이에 차이가 없었다. (3) Ascorbate 첨가 우유시료는 냉동건조/복원에 의하여 관능적 특성이 저하되었고, ascorbate 첨가 난백분말시료는 냉동건조/복원에 의하여 관능적 특성이 변화하지 않았다. (4) 휘발성 향기 성분의 분석 결과를 보면, 냉동건조에 의하여 모든 휘발성 향기 성분 함량이 감소하였으며, 우유시료군과 난백분말시료군 사이에는 회수율이 다소 다른 pattern을 보였다. (5) 휘발성 향기성분의 종류에 따라 다르지만 우유시료군과 난백분말 시료군의 휘발성 향기 성분 함량은 냉동건조 전에는 차이가 비교적 컸으나, 냉동건조/복원한 후에는 차이가 비교적 작았다. (6) 냉동건조에 의하여 우유시료군의 물성은 크게 변화하였으나, 난백분말시료군의 물성변화는 비교적 작았다.

• 산업경영시스템학회지
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• 제42권1호
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• pp.151-157
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• 2019

This study is about the process capability index (PCI). In this study, we introduce several indices including the index $C_{PR}$ and present the characteristics of the $C_{PR}$ as well as its validity. The difference between the other indices and the $C_{PR}$ is the way we use to estimate the standard deviation. Calculating the index, most indices use sample standard deviation while the index $C_{PR}$ uses range R. The sample standard deviation is generally a better estimator than the range R. But in the case of the panel process, the $C_{PR}$ has more consistency than the other indices at the point of non-conforming ratio which is an important term in quality control. The reason why the $C_{PR}$ using the range has better consistency is explained by introducing the concept of 'flatness ratio'. At least one million cells are present in one panel, so we can't inspect all of them. In estimating the PCI, it is necessary to consider the inspection cost together with the consistency. Even though we want smaller sample size at the point of inspection cost, the small sample size makes the PCI unreliable. There is 'trade off' between the inspection cost and the accuracy of the PCI. Therefore, we should obtain as large a sample size as possible under the allowed inspection cost. In order for $C_{PR}$ to be used throughout the industry, it is necessary to analyze the characteristics of the $C_{PR}$. Because the $C_{PR}$ is a kind of index including subgroup concept, the analysis should be done at the point of sample size of the subgroup. We present numerical analysis results of $C_{PR}$ by the data from the random number generating method. In this study, we also show the difference between the $C_{PR}$ using the range and the $C_P$ which is a representative index using the sample standard deviation. Regression analysis was used for the numerical analysis of the sample data. In addition, residual analysis and equal variance analysis was also conducted.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2331-2334
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• 2003

The basic difference between the EKF(Extended Kalman Filter) and UKF(Unscented Kalman Filter) stems from the manner in which Gaussian random variables(GRV) are represented for propagating through system dynamics. In the EKF, the state distribution is approximated by a GRV, which is then propagated analytically through the first-order linearization of the nonlinear system. This can possibly introduce large errors in the true posterior mean and covariance of the transformed GRV, which may lead to sub-optimal performance and sometimes divergence of the filter. However, the UKF addresses this problem by using a deterministic sampling approach. The state distribution is also approximated by a GRV, but is now represented using a minimal set of carefully chosen sample points. These sample points completely capture the true mean and covariance of the GRV, and UKF captures the posterior mean and covariance accurately up to the 2nd order(Taylor series expansion) for any nonlinearity. This paper utilizes the UKF to determine spacecraft orbit when only magnetometer is available. Several catastrophic failures of spacecraft in orbit have been attributed to failures of the spacecraft mission. Recently studies on contingency-major sensor failure cases- have been performed. For mission success, contingency design or plan should be implemented in case of a major sensor failure. Therefore the algorithm presented in this paper can be used for a spacecraft without GPS or contingency design in case of GPS failure.

• 대한가정학회지
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• 제29권2호
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• pp.185-197
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• 1991

The purpose of this study is to explore family relations of the Elderly influencing adjustment of the Elderly. The Sample was selected from elderly women who are older than 65years living in Seoul. Total sample consisted of 324 elderly women(married women 155, widow 169) finally selected datum sources. Factor analysis, frequency distribution, percentile, Anova, Pearson's Correlation and Stepwise multiple regression were used to take statistics. The main resluts were as follows: 1. The score of the adjustment of urban elderly woman was normal. 2. General characteristic variables such as age, self-reported health, financial status and supply of living expenses have turned out to be significant on the adjustment of the elederly women. 3. General satisfaction of married life, among the subordinate dimensions of the aging Couple relationships, has influence of the adjustment of the elderly women. 4. Among the old parent-Adult children relationships, subjective solidarity and consensual solidarity have influence on the adjustement of the aged. Besides the above two solidarity, objective solidarity has influence on the adjustment, in the case of widow. 5. Among the grandmother-grandchildren relationships, discipliner relations and material provider relations have influence on the adjustment of the married old women. Besides the above two solidarity, surrogate parenting relation have influence on the adjustment, in the case of widow.

• 한국생산제조학회지
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• 제21권4호
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• pp.525-531
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• 2012

This study aims at the structural analysis of vibration and fatigue according to the configuration of engine mount. Maximum equivalent stress or deformation is shown at bracket or case respectively. As harmonic vibration analysis, the maximum displacement amplitude is happened at 4,000Hz. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' or 'Saw tooth' becomes most stable. In case of 'Sample history' or 'Saw tooth' with the average stress of 4,200MPa or 0MPa and the amplitude stress of -3,000MPa or 7MPa, the possibility of maximum damage becomes 70%. This stress state can be shown with 7 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design on engine mount by investigating prevention and durability against its damage.

• Asian Journal of Atmospheric Environment
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• 제9권1호
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• pp.86-90
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• 2015

Temperature was considered to estimate the minimum detectable absorption coefficient of aerosol particles from photothermal spectroscopy. Light energy absorbed by subsequent emission from the aerosol results in the heating of the aerosol sample and consequently causes a temperature change as well as changes in thermodynamic parameters of the sample. This thermal effect is the basis of photothermal spectroscopy. Photothermal spectroscopy has several types of techniques depending on how the photothermal effects are detected. Photothermal interferometry traces the photothermal effect, refractive index, using an interferometer. Photoacoustic spectroscopy detects the photothermal effect, sound wave, using a microphone. In this study, it is suggested that the detection limit for photothermal spectroscopy can be influenced by the introduction of a slip correction factor when the light absorption is determined in a high temperature environment. The minimum detectable absorption coefficient depends on the density, the specific heat and the temperature, which are thermodynamic properties. Without considering the slip correction, when the temperature of the environment is 400 K, the minimum detectable absorption coefficient for photothermal interferometry increases approximately 0.3% compared to the case of 300 K. The minimum detectable absorption coefficient for photoacoustic spectroscopy decreases only 0.2% compared to the case of 300 K. Photothermal interferometry differs only 0.5% point from photoacoustic spectroscopy. Thus, it is believed that photothermal interferometry is reliably comparable to photoacoustic spectroscopy under 400 K.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.15-16
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• 2006

The thermal stability of nickel silicide with compressively and tensilely stressed nitride capping layer has been investigated in this study. The Ni (10 nm) and Ni/Co/TiN (7/3/25 nm) structures were deposited on the p-type Si substrate. The stressed capping layer was deposited using plasma enhanced chemical vapor deposition (PECVD) after silicide formation by one-step rapid thermal process (RTP) at $500^{\circ}C$ for 30 sec. It was found that the thermal stability of nickel silicide depends on the stress induced by the nitride capping layer. In the case of Ni (10 nm) structure, the high compressive sample shows the best thermal stability, whereas in the case of Ni/Co/TiN (7/3/25 nm) structure, the high compressive sample shows the worst thermal stability.

• 한국동물위생학회지
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• 제32권3호
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• pp.215-218
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• 2009

The dog breeding kennel bacterial infection are very significant in perinatal mortality. In many case, Staphylococcus aureus, Streptococcus, and Escherichia coli were infected in intra-uterine or by the genital tract to the puppies, and they are cause of septicemic death of the puppies and clinical mastitis of bitch, leading to septicemic death of newborn puppies. Severe mastitis due to bacterial infection was diagnosed in a 2 year-old female Brittany Spaniel which loss 6 puppies with odor small rice sharp white diarrhea of nine puppies. Bright curd milk and intestinal sample were inoculated on MacConkey agar, blood agar and brain heart infusion agar, and incubated at $37^{\circ}C$ for 24-48 hrs. Gram negative colonies isolated from these sample which were characterized as Glu, Ure, $H_2S$, Orn, Cit, and Cl, and were identified by Microscan Walk-Aways Baxter, American Type Culture Collection, USA) as Proteus mirabils. The isolate was more sensitive to ampicillin, gentamicin, cefoxitin, cefuroxime, and cefazidime. In this results, we confirmed that cause bacteria of septicemic death in puppies was P. mirabilis.