• Survey Research
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• v.7 no.2
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• pp.53-69
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• 2006

Weights can be made and imposed in both sample design stage and analysis stage in a sample survey. While in design stage weights are related with sample data acquisition quantities such as sample selection probability and response rate, in analysis stage weights are connected with external quantities, for instance population quantities and some auxiliary information. The final weight is the product of all weights in both stage. In the present paper, we focus on the weight in analysis stage and investigate the effect of such weights imposed on the weighted mean when estimating the population mean. We consider a finite population with a pair of fixed survey value and weight in each unit, and suppose equal selection probability designs. Under the condition we derive the formulas of the bias as well as mean square error of the weighted mean and show that the weighted mean is biased and the direction and amount of the bias can be explained by the correlation between survey variate and weight: if the correlation coefficient is positive, then the weighted mein over-estimates the population mean, on the other hand, if negative, then under-estimates. Also the magnitude of bias is getting larger when the correlation coefficient is getting greater. In addition to theoretical derivation about the weighted mean, we conduct a simulation study to show quantities of the bias and mean square errors numerically. In the simulation, nine weights having correlation coefficient with survey variate from -0.2 to 0.6 are generated and four sample sizes from 100 to 400 are considered and then biases and mean square errors are calculated in each case. As a result, in the case or 400 sample size and 0.55 correlation coefficient, the amount or squared bias of the weighted mean occupies up to 82% among mean square error, which says the weighted mean might be biased very seriously in some cases.

• Journal of Digital Convergence
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• v.14 no.11
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• pp.193-199
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• 2016

The aim of this study is to determine factors that affect the competitiveness and the move-in environment of migration companies according to the recent change of location conditions of industrial complexes. The results of analysis show that productive factor and economic factor are related to the main factors that determine the location environment. The resident companies have a strong link to the economic characteristics factors, which seems to be related to the expectation and satisfaction for public support facilities, hospitals, educational institutions, and administrative agencies to be placed in the complex, encouraging companies to be located in the complex. In other words, if the existing economic factors and public support facilities were complemented, it can be inferred that the industrial complex promotion policies will be more effectively planned. Also, transportation and infrastructure facilities are analyzed as successful factors for resident companies. In addition, the economic and productive environments turn out to affect public support facilities and environmental factors of infrastructure as major factors. The results of this study are expected to be a useful guideline in determining the resident policy or external factors for the future industrial complex.

• Korean Journal of Health Education and Promotion
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• v.15 no.1
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• pp.133-149
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• 1998

본 연구는 미국에 사는 한국인 이민자들의 암예방과 식품에 대한 지식과 신념에 관하여 알아보는데 그 목적이 있다. 본 연구의 도구로는 미국 국민 건강연구조사 (NHIS)의 설문지를 한국어로 번역하였고, 연구의 대상자는 미국의 시카고에 거주하는 263명의 한국인 이민자들이다. 본 연구의 주된 연구결과는 다음과 같았다. (1) 대부분의 대상자(83.3%)들은 한국음식을 먹고 있다고 답하였다. (2) 대상자들의 47.5%가 영어를 전혀 못 읽거나 거의 못 읽는다고 답하였다. (3) 식생활 변화를 하지 않는 이유에 대해 현재 먹고 있는 음식을 즐기기 때문에 식생활을 바꾸고 싶지 않다는 답이 가장 많았다. (4) 우리가 먹고 마시는 음식과 관계 있는 주요질병에 대해서 25.4%의 응답자만이 암이라고 답하였다 (미국 NHIS 에서는 48%). (5) 응답자의 48.3%만이 섬유소에 대해 들어보았다고 응답하였다. (6) 7.1%의 응답자만이 섬유소가 많은 음식으로 corn flakes와 bran flakes를 고를 수 있었다. 이 결과로 보아 한국인 이민자들이 미국음식에 대해 잘 모르는 것으로 보인다. (7) 약 62%의 응답자들이 암예방에 관한 무료 보건강좌에 참석하고 싶다고 응답하였다. 보건강좌 장소에 대해 "교회'라고 답한 응답자가 가장 많았다. (8) 질병예방에 관한 정보를 어디에서 얻느냐는 질문에 대하여 "신문"이라고 답한 응답자가 가장 많았다. 본 연구에서 얻은 결과를 볼 때 대부분의 응답자들이 미국 정부에서 하고 있는 암예방 교육의 혜택을 받고 있지 않는 것으로 나타났다. 한국인 이민자들의 문화적 배경에 맞는 암교육이 필요하며, 영어를 잘 못하는 이민자들을 위해 한국말로 번역된 보건교육자료를 사용하여야 한다.교육자료를 사용하여야 한다.표현을 위하여 확장된 기본 모델을 중심으로 각 레벨의 구성 요소들의 형식적 의미(formal semantics)와 레벨 내 혹은 레벨 구성요소들간의 관계성(relationship), 그리고 제약조건의 표현과 질의 추론 규칙들을 식별하여 FOPL(First Order Predicate Logic)로 표현한다. 또한, 본 논문은 FOPL로 표현된 predicate들과 규칙들을 구현하기 위하여 Prolog로 변환하기 위한 이론적 방법론을 제시하고 정보자원 관리를 위한 기본 함수들과 스키마 진화(schema evolution)를 위한 방법론을 제안한다. 최저 잔류탁도를 나타내는 최적 응집제 주입량에서의 Zeta potential은 원수탁도가 5NTU일 경우 Alum, PAC 및 PACS 모두 -20mV∼-15mV사이였으며, 원수 탁도가 10NTU인 경우에는 0∼0.5mV 범위에 있는 것으로 나타나 응집제 종류 및 주입량이 상이하더라도 응집효율이 가장 양호한 상태에서의 Zeta potential은 일정한 범위내에 있는 것으로 나타났다.각 각 11.1, 10.2, 12.2 그리고 13.0%의 발달율을 보여 유의적인 차이를 보이지 않았다. 4. 수정 후 114 시간 개별배양된 수정란으로부터 분리된 small과 large의 할구를 공핵체로 사용한 처리구에서 핵이식 수정란의 세포융합율에 있어서 각각 71.0, 71.4, 69.9 및 77.1% 의 융합율올 보여 유의적인 차이를 나타내지 않았으며, 핵이식 수정란의 배반포기배로의 발달율에 있어서도 각각 11.4%, 8.0%, 17.2% 그리고 12.9% 의 발달율을 보여 유의적인 차이를 보이지 않았다. 이상의 결과로 보아 핵이식 수정란을 효율적으로 생산하기 위하여 수핵난자의 세포질에 ionomycin 과 DMAP 의

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.65-77
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• 2016

Modeling for complex reacting flow in Fischer-Tropsch reactor is one of the challenges in the field of Computational Fluid Dynamics (CFD). It is hard to derive each and every reaction rate for all chemical species because Fisher-Tropsch reaction produces many kinds of hydrocarbons which include lots of isomers. To overcome this problem, after analyzing the existing methodologies for reaction rate modeling, non-Anderson-Schulz-Flory methodology is selected to model the detailed reaction rates. In addition, the inside flow has feature of multi-phase flow, and the methodologies for modeling multi-phase flow depend on the interference between the phases, distribution of the dispersed phase, flow pattern, etc. However, existing studies have used a variety of inside flow modeling methodologies with no basis or rationale for the feasibility. Modeling inside flow based on the experimental observation of the flow would be the best way, however, with limited resources we infer the probable regime of inside flow based on conventional fluid dynamics theory; select the appropriate methodology of Mixture model; and perform systematic CFD modeling. The model presented in this study is validated through comparisons between experimental data and simulation results for 10 experimental conditions.

• Journal of the Korean Chemical Society
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• v.32 no.4
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• pp.318-322
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• 1988

We studied the aquation reaction of s-cis-$[Co(eee)Cl_2]^+$ and s-cis-$[Co(eee)Br_2]^+$ complex ions under the various temperatures and pressures. In these complexes eee is $NH_2-CH_2CH_2-S-CH_2CH_2-NH_2$. The rate law of the aquation reactions of these two complexes obeys $Rate = k_{obsd}$[CO(III)], where rate constants of s-cis-$Co(eee)Cl_2]^+$ and s-cis-$[Co(eee)Br_2]^+$ respectively are $0.687{\times}10^{-4}$ $sec^{-1}$ and $4.10{\times}10^{-4}$ $sec^{-1}$ in condition of 0.1M $HClO_4\;and\;40^{\circ}C$. In the same condition, the activation entropies of s-cis-[Co(eee)$Cl_2$]+ and s-cis-(Co(eee)Br_2$]+ complexes respectively are -15.5 eu and -7.54eu, and the activation volumes are $-4.6cm^3mole^{-1}$ and $-4.2cm^3mole^{-1}$. From these data, we could infer the mechanism of the aquation reaction as the interchange dissociation (Id) mechanism.

• The KIPS Transactions:PartB
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• v.9B no.5
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• pp.625-634
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• 2002

In this paper, we conducted various experiments with Bayesian networks in order to analyze clinical data of infertility patients. With these experiments, we tried to find out inter-dependencies among important factors playing the key role in clinical pregnancy, and to compare 3 different kinds of Bayesian network classifiers (including NBN, BAN, GBN) in terms of classification performance. As a result of experiments, we found the fact that the most important features playing the key role in clinical pregnancy (Clin) are indication (IND), stimulation, age of female partner (FA), number of ova (ICT), and use of Wallace (ETM), and then discovered inter-dependencies among these features. And we made sure that BAN and GBN, which are more general Bayesian network classifiers permitting inter-dependencies among features, show higher performance than NBN. By comparing Bayesian classifiers based on probabilistic representation and reasoning with other classifiers such as decision trees and k-nearest neighbor methods, we found that the former show higher performance than the latter due to inherent characteristics of clinical domain. finally, we suggested a feature reduction method in which all features except only some ones within Markov blanket of the class node are removed, and investigated by experiments whether such feature reduction can increase the performance of Bayesian classifiers.

• Resources Recycling
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• v.26 no.5
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• pp.54-60
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• 2017

In this study, we investigated the effect of $TiCl_4$ injection time on the Kroll reaction at a given weight ratio of $TiCl_4$ and Mg. The reduction reaction was investigated by measuring the temperature change according to $TiCl_4$ injection time and observing the cross section and appearance of the Ti sponge after the reaction. The temperature increment due to Kroll reaction heat generation was found to be linearly proportional to the $TiCl_4$ feed rate. In the graph of $TiCl_4$ injection time and reduction tank temperature, initial temperature peaks were observed irrespective of the injection conditions. This is interpreted to mean a temporary interruption of reaction due to $MgCl_2$ formation after the initial Kroll reaction. In addition, when the cross section of the sponge was observed, a large amount of spherical Mg particles was observed in $MgCl_2$. We can infer that this is the process of continuously feeding the unreacted Mg surface, so that a continuous Kroll reaction takes place. The sponge appearance showed that the coalescence or growth of the Kroll reacted Ti particles can be controlled by the cooling rate.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.353-357
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• 2011

For the purpose of introducing hydrophilic function to pristine PVDF, pristine PVDF was modified under atmosphere and aqueous vapor by irradiating electron beam (EB). EB dose was varied from 0 to 125 K Gray, respectively. Their changes of chemical composition /structure were observed and evaluated by FT-IR, EDS and DSC. Also, their surface behaviors were evaluated by contact angle. In FT-IR study, it was confirmed that hydroxyl functions were introduced to pristine PVDF. In EDS analysis, mole ratio of F (fluoride) was almost constant (about 33%) in spite of increasing EB dose, meaning that hydroxyl function was introduced via dehydrozenation, not via deflurodination. In DSC study, $T_g$ increased with increasing EB dose, which was reconfirmed that hydroxyl function was introduced via dehydrozenation. $T_m$ increased with increasing EB dose, inferring that the increase in EB dose led to more outbreak of hydroxyl function which led to more enhanced hydrogen bond. In the result of contact angle, pristine PVDF film was $62^{\circ}$ and 125 K Gray-irradiated PVDF film was even $13^{\circ}$. All results showed that pristine PVDF was successfully changed to hydrophilic PVDF.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.555-564
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• 2021

Thalamus is known to play an important role in the regulation of nerve function. Thalamus, located in the center of the brain, is involved in sleep, arousal, and emotional regulation, and has been reported to be associated with multiple sclerosis, essential tremors, and neurodegenerative diseases such as Parkinson's disease. In addition, it has been reported that iron deposits in the thalamus can cause depressive symptoms with age. Although there are discrepancies between studies, it can be deduced that the thalamus region has a clear effect on neurological disorders due to a strong relationship between the thalamus and neurological functions such as emotional control and processing. Through tractography analysis, the connectivity between the detailed areas of each subcortical region was investigated in the form of a matrix, showing strong connectivity and weak interhemispheric connectivity. In the 59> group, the WM connectivity of thalamus was found to be weaker than those of the two groups. Comparisons between the two groups showed that the young groups (10-39 and 40-59) had higher connection intensity than the 59> group and that statistically significant differences in 3 connection pathways were found in each hemisphere. A decrease in thalamus-related connection strength in aging has shown that it can affect emotional and neurological disorders such as anxiety and depression, and network measurements can help assess cognitive impairment across clinical conditions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.59-66
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• 2021

Humans mainly recognize surrounding objects using visual and auditory information among the five senses (sight, hearing, smell, touch, taste). Major research related to the latest object recognition mainly focuses on analysis using image sensor information. In this paper, after emitting various chirp audio signals into the observation space, collecting echoes through a 2-channel receiving sensor, converting them into spectral images, an object recognition experiment in 3D space was conducted using an image learning algorithm based on deep learning. Through this experiment, the experiment was conducted in a situation where there is noise and echo generated in a general indoor environment, not in the ideal condition of an anechoic room, and the object recognition through echo was able to estimate the position of the object with 83% accuracy. In addition, it was possible to obtain visual information through sound through learning of 3D sound by mapping the inference result to the observation space and the 3D sound spatial signal and outputting it as sound. This means that the use of various echo information along with image information is required for object recognition research, and it is thought that this technology can be used for augmented reality through 3D sound.