• Journal of Periodontal and Implant Science
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• v.50 no.6
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• pp.358-367
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• 2020

Purpose: The aim of this study was to investigate the efficacy and validity of subgingival bacterial sampling using a retraction cord, and to evaluate how well this sampling method reflected changes in periodontal conditions after periodontal therapy. Methods: Based on clinical examinations, 87 subjects were divided into a healthy group (n=40) and a periodontitis group (n=47). Clinical measurements were obtained from all subjects including periodontal probing depth (PD), bleeding on probing (BOP), clinical attachment loss (CAL), and the plaque index. Saliva and gingival crevicular fluid (GCF) as a subgingival bacterial sample were sampled before and 3 months after periodontal therapy. The salivary and subgingival bacterial samples were analyzed by reverse-transcription polymerase chain reaction to quantify the following 11 periodontal pathogens: Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythus (Tf), Treponema denticola (Td), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Pavimonas micra (Pm), Campylobacter rectus (Cr), Prevotella nigrescens (Pn), Eikenella corrodens (Ec), and Eubacterium nodatum (En). Results: Non-surgical periodontal therapy resulted in significant decreases in PD (P<0.01), CAL (P<0.01), and BOP (P<0.05) after 3 months. Four species (Pg, Tf, Pi, and Pm) were significantly more abundant in both types of samples in the periodontitis group than in the healthy group. After periodontal therapy, Cr was the only bacterium that showed a statistically significant decrease in saliva, whereas statistically significant decreases in Cr, Pg, and Pn were found in GCF. Conclusions: Salivary and subgingival bacterial sampling with a gingival retraction cord were found to be equivalent in terms of their accuracy for differentiating periodontitis, but GCF reflected changes in bacterial abundance after periodontal therapy more sensitively than saliva.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• Korean Journal of Heritage: History & Science
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• v.34
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• pp.138-171
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• 2001

This paper, based on the filed survey conducted from August 14 to 21, 2000, examines the architectural characteristics of traditional dwellings of Sujeonchon(수전촌, 水田村) village. Sujeonchon village is located on the northen slope of Changbaishan Mt., Andohyun(안도현, 安圖縣) of jilin Province(吉林省), a province in the northeastern region of China. The village was established between late 1940's and early 1950's by the Korean-Chinese. Later on, some of the Korean-Chinese residents moved out of the village and presently, the residents are composed of both the Korean-Chinese and the Chinese consisting about fifty-fifty. Since the cultural background and the living custom are different from each other ethnic group, that is, the Korean-Chinese and the Chinese, their dwellings reveal some differences between them. Through the study, the architectural characteristics and distinctions of the Korean-Chinese and Chinese dwellings are found and summarized as follows: 1.The way of building layout is different between them: the Chinese mainly follows the north-south direction of building layout, while the Korean-Chinese considers the surrounding environmental condition. 2.The floor level of kitchen is different between them: that of the Chinese house is same as the outdoor earth level, while that of the Korean-Chinese is lower than the outdoor level. 3.The way of providing the kitchen space is different between them: the kitchen of the Chinese house is consist of one separate room, while that of the Korean-Chinese is open to the living area. 4.The way of heating system is different between them: the Chinese house has kang only at the sleeping area, while the Korean-Chinese install whole under-floor heating of gudeul in the living area. 5.The attitude to the way of building is different between them: the Chinese are easily adapt to the new building materials and construction method, while the Korean-Chinese are showing strong attachment to the traditional way of building. 6.The houses of the Chinese and the Korean-Chinese have their own traditional ornaments and talismans on and in the building.

• Journal of Periodontal and Implant Science
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• v.48 no.6
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• pp.337-346
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• 2018

Purpose: Peripheral artery disease (PAD) is a form of arteriosclerosis that occurs in the extremities and involves ischemia. Previous studies have reported that patients with periodontitis are at high risk for PAD. However, the relationship between these 2 diseases has not yet been fully elucidated. In this cross-sectional study, we investigated this relationship by comparing patients with PAD to those with arrhythmia (ARR) as a control group. Methods: A large-scale survey was conducted of patients with cardiovascular disease who visited Tokyo Medical and Dental University Hospital. We investigated their oral condition and dental clinical measurements, including probing pocket depth, bleeding on probing, clinical attachment level, and number of missing teeth; we also collected salivary and subgingival plaque samples and peripheral blood samples. All patients with PAD were extracted from the whole population (n=25), and a matching number of patients with ARR were extracted (n=25). Simultaneously, ARR patients were matched to PAD patients in terms of age, gender, prevalence of diabetes, hypertension, dyslipidemia, obesity, and the smoking rate (n=25 in both groups). Real-time polymerase chain reaction was performed to measure the bacterial counts, while the enzyme-linked immunosorbent assay method was used to measure anti-bacterial antibody titers and proinflammatory cytokine levels in serum. Results: PAD patients had more missing teeth ($18.4{\pm}2.0$) and higher serum levels of C-reactive protein ($1.57{\pm}0.85mg/dL$) and tumor necrosis factor-alpha ($70.3{\pm}5.7pg/mL$) than ARR patients ($12.0{\pm}1.7$, $0.38{\pm}0.21mg/dL$, and $39.3{\pm}4.5pg/mL$, respectively). Meanwhile, no statistically significant differences were found in other dental clinical measurements, bacterial antibody titers, or bacterial counts between the 2 groups. Conclusions: Our findings suggested that PAD patients had poorer oral and periodontal state with enhanced systemic inflammation.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.41-45
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• 2018

We have simulated the process induced warpage for panel level package using finite element method. Silicon chips of $5{\times}5mm^2$ were redistributed on $122.4{\times}93.6mm^2$ size panel and the total number of redistributed chips was 221. The warpage at each process step, for example, (1) EMC molding, (2) attachment of detach core, (3) heating, (4) removal of a carrier, and (5) cooling was simulated using ANSYS and the effects of detach core and carrier materials on the warpage were investigated. The warpage behaved complexly depending on the materials for the detach core and carrier. However, glass carrier showed the lower warpage than FR4 carrier regardless of detach core material, and the minimum warpage was observed when the glass was used for the detach core and carrier at the same time.

• Journal of radiological science and technology
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• v.44 no.4
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• pp.389-397
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• 2021

The purpose of this study was to compare the demographic and job characteristics and job satisfaction of sonographers (SONO) and radiological technologists (RT). The subjects were a total of 148 people (69 SONO, 79 RT), who had been working in clinical and hospitals. The method was conducted using a questionnaire with a total of 54 questions consisting of demographic characteristics, job characteristics, and job satisfaction. Reliability was secured with Cronbach's alpha coefficient of 0.6 or higher for the response of the questionnaire. For statistical analysis, descriptive statistics, cross-analysis, independent sample T-test, and correlation analysis using Pearson's correlation coefficient and Spearman's correlation coefficient were performed for each occupation. As a result, first, the SONO had more female workers than RT. They are more than three times as many in graduate school and above. Second, the SONO had 4.5 times more morning shift than the RT and no form of weekend shift. Third, the average monthly salary of the SONO is higher than that of the RT, but when a certain portion of the salary goes up, the salary no longer goes up. Fourth, satisfaction with expectations, growth desire, positive mentality, growth opportunity, job importance, organizational attachment was higher SONO than the RT, but self-efficacy was higher in RT than SONO. Last, SONO had higher educational background than RT. It is hoped that the results of this study will be able to understand the job characteristics of SONO and RT and identify the factors of job satisfaction and provide them as fundamental materials for job selection.

• Journal of agriculture & life science
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• v.51 no.1
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• pp.205-212
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• 2017

This study aimed to output augmented reality display using chroma-key so that power tiller simulator can be operated smoothly while wearing the head mounted display. In this paper, we propose a chroma-eliminating image filtering method. Experimental results show that the maximum and minimum values of hue, saturation and intensity were 0.52, 0.153, 0.57, 0.16, 1, and 0.12, respectively. A keypad was used to set the initial position of augmented reality adjusted with the front, back, top, bottom, left, and right buttons. The initial position value is always maintained and managed according to the trailer attachment and detachment. Finally, we show that the augmented reality merged with virtual image and the acquired image of operation device using coordinate values obtained from the HMD and the position tracking sensor as relative coordinates in Unity program that is the ultimate game development platform.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.55-62
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• 2021

The mandible has a smaller support area than the maxilla, and in particular, in patients with generalized alveolar bone resorption, the stability of the denture and the masticatory efficiency are significantly low in the case of conventional complete denture, due to the movement of the tongue and mandible. In these patients, implant overdenture is evaluated as a highly predictable treatment method with high retention and stability, and excellent pronunciation and masticatory force. In this clinical case, patient had an edentulous maxilla and generalized alveolar bone resorption in mandible. Therefore, complete denture was placed in the maxilla and implant overdenture using milled bar attachment on 4 implants was placed in the mandible. During the 12-year follow-up period, changes in periodontal tissue and denture around the implants were periodically managed and observed.

• The Journal of Information Systems
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• v.30 no.2
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• pp.29-56
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• 2021

Purpose Cyber deviance of adolescents has become a serious social problem. With a widespread use of smartphones, incidents of cyber deviance have increased in Korea and both quantitative and qualitative damages such as suicide and depression are increasing. Research has been conducted to understand diverse factors that explain adolescents' delinquency in cyber space. However, most previous studies have focused on a single theory or perspective. Therefore, this study aims to comprehensively analyze motivations of juvenile cyber deviance and to develop a predictive model for delinquent adolescents by integrating four different theories on cyber deviance. Design/methodology/approach By using data from Korean Children & Youth Panel Survey 2010, this study extracts 27 potential factors for cyber deivance based on four background theories including general strain, social learning, social bonding, and routine activity theories. Then this study employs econometric analysis to empirically assess the impact of potential factors and utilizes a machine learning approach to predict the likelihood of cyber deviance by adolescents. Findings This study found that general strain factors as well as social learning factors have positive effects on cyber deviance. Routine activity-related factors such as real-life delinquent behaviors and online activities also positively influence the likelihood of cyber diviance. On the other hand, social bonding factors such as community commitment and attachment to community lessen the likelihood of cyber deviance while social factors related to school activities are found to have positive impacts on cyber deviance. This study also found a predictive model using a deep learning algorithm indicates the highest prediction performance. This study contributes to the prevention of cyber deviance of teenagers in practice by understanding motivations for adolescents' delinquency and predicting potential cyber deviants.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.195-201
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• 2022

Hemimandibulectomy and free fibular flap (FFF) in patients with squamous cell carcinoma could disturb the functional movement of the mandible. The muscular function in the sectioned side was compromised because of the incompetency of the muscle attachment to the mandible, leading to the unstable occlusal contact in the centric and eccentric occlusion. In this report, we present a case of a 63-year-old male who underwent cancer surgery and reconstruction with fibular graft, and he needed a fixed dental prosthesis to restore tooth loss in the anterior region. Occlusal contact change and instability were found according to the bite force in the centric relation and eccentric movement. This case report aimed to present the prosthetic procedure for fabricating the functionally optimized fixed prosthesis wherein the functionally generated path (FGP) technique and digital imaging method were applied to replicate mandibular movement and vertical dimension of the patient.