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- 저자 : 정승화 ( Seung-hwa Jeong ) (검색결과 47 건)
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정승화(Seung-Hwa Jeong),유혜정(Hye-Jeong Yoo) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.4
With the rapid increasement of information security-related incidents, many companies and organizations operate the information security systems. The conventional way of monitoring and control of information security is to operate information security systems such as IDS and IPS based on the pattern detection. However, most of the information security systems have many restrictions on the packet analysis because they cannot output a string normally that is contained in a packet. So, they need to perform separate decoding operations at every event. In this paper, we propose an automatic packet decoding algorithm of multibyte characters in encoded data. This proposed algorithm solves the problem of character conversion completely including Hangul. This algorithm brings time efficiency and the improvement of packet analysis.
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정승화 ( Seung Hwa Jeong ),권호근 ( Ho Keun Kwon ),김백일 ( Baek Il Kim ) 대한예방치과·구강보건학회 2010 大韓口腔保健學會誌 Vol.34 No.4
Objectives. The aim of this study was to assess the influence of storage methods on the enamel specimen. Methods. Each enamel specimen (3 mm in diameter) from bovine anterior teeth was stored in 5 mL of 6 kinds of media which were saline, distilled water, thymol solution (0.1%), Hank`s balanced salts solution (HBSS), ethanol (70%) and frozen at -20℃ for 25 and 125 days. In order to evaluate effects of each storage method, surface micro hardness (VHN) of enamel surface was measured before and after storage of specimens. Also, confocal laser scanning microscope (CLSM) and polarized light microscope (PLM) were used to observe the sagittal section of the enamel specimen. Results. After storage for 25 days in the saline, distilled water, 0.1% thymol solution and HBSS media, the micro hardness of the enamel surface have decreased significantly (p<0.01). In contrast, storing teeth in 70% ethanol and freezing at -20℃ did not have significant difference in the micro hardness before and after storage. After storage for 125 days, only freezing at -20℃ showed no storage effect to the enamel surface. Conclusions. It was concluded that 70% ethanol and freezing at -20℃ with no surface contact of water could be proper methods for storage of teeth in micro hardness study. So, we recommend that extracted teeth and tooth specimens should be shortly stored in the 70% ethanol for disinfection process, and then be stored with freezing temperature of -20℃ with no surface contact of water.
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정승화(Seung-Hwa Jeong) 한국콘텐츠학회 2021 한국콘텐츠학회논문지 Vol.21 No.8
COVID-19 대유행으로 급속히 침체하였던 국내외 항공업계는 바이러스 백신 접종을 시작으로 조심스럽게 경영 정상화를 준비하고 있으며, 국내 및 근거리 해외 시장을 공유하고 있는 대형항공사와 저비용항공사 간의 경쟁 역시 다시 치열해질 것으로 예상한다. 이러한 상황에서 지금까지 국가, 도시, 일부 기업을 대상으로 이루어지던 브랜드 자산에 관한 연구를 국내 항공사 대상으로 진행하였다. 본 연구는 대상의 인식, 가치, 태도, 신념과 같은 개념을 연구하기 위해 양적·질적 연구 방법의 한계를 보완하고자 제안된 Q 방법론을 적용하였다. 연구 결과, 항공사 브랜드 이용자들은 실속 추구형, 가치 지향형, 업무 관련형의 총 3가지 유형이 도출되었고, Q 표본으로부터 25개 진술문을 확보하고 20명으로 구성된 P 표본의 주관성을 관찰하여 유형별 특징을 구체적으로 살펴보았다. 대형항공사와 저비용항공사의 브랜드 자산 유형을 탐색하고, 소비자의 인식을 비교함으로써 항공사 브랜드 자산의 효율적 관리에 전략적 방향을 제시하고, 후속 연구를 위한 가설을 제공한다는 측면에서 의의가 있다. Many domestic and international airlines that experienced dramatic recession due to COVID-19 pandemic are carefully being ready to normalise operations as a number of governments has begun to vaccinate for COVID-19. So with the same market share from domestic to short distant international services, the competition between Full Service Carriers (FSC) and low cost carriers (LCC) is anticipated to be more intensive. To explore the concepts such as the perception, value, attitude and faith of the object, this study implements Q methodology proposed to complement the limitations of quantitative and qualitative research methodology. As a result, the consumers of airlines’ brand are divided into three types – the type of utility seeking, value-oriented and task-related. Using Q samples which consist of 25 statements, this study specifically approached the traits of each type by observing the subjectivity with the comparative P sample group that is made up for 20 participants. By discovering the type of FSC and LCC’s brand asset and comparing the recognition of consumers, not only does this study evoke the need for a strategic direction of the effective management of Airlines’ Brand asset but also have a signification in the way that especially provide hypotheses for follow up studies.
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성장배지 혈액 유무가 구강미생물의 적색 형광 발현에 미치는 영향
정승화 ( Seung-hwa Jeong ),양용훈 ( Yong-hoon Yang ),이민아 ( Min-ah Lee ),김세연 ( Se-yeon Kim ),김지수 ( Ji-soo Kim ) 대한예방치과·구강보건학회 2017 大韓口腔保健學會誌 Vol.41 No.4
Objectives: Dental plaque emits red fluorescence under a visible blue light near the ultra-violet end of the light spectrum. The fluorescence characteristics of each microorganism have been reported in sev eral studies. The aim of this study was to evaluate changes in red fluorescence of oral microorganisms that is affected by blood in the culture media. Methods: The gram-positive Actinomyces naeslundii (AN, KCTC 5525) and Lactobacillus casei (LC, KCTC 3109) and gram negative Prevotella intermedia (PI, KCTC 3692) that are known to emit red fluorescence were used in this study. Each bacterium was activated in broth and cultivated in different agar media at 37℃ for 7 days. Tryptic soy agar with hemin and vitamin K<sub>3</sub> (TSA), TSA with sheep blood (TSAB), basal medium mucin (BMM) medium, and BMM with sheep blood (BMMB) were used in this study. Fluorescence due to bacterial growth was observed under 405-nm wavelength blue light using the quantitative light-induced fluorescence-digital (QLF-D) device. The red, green, and blue fluorescence values of colonies were obtained using image-analysis software and the red to green ratio (R/G value) and red to total RGB ratio (R/RGB value) were calculated for quantitative comparison. Results: The QLF-D images of the AN, LC, and PI colonies showed red fluorescence in all media, but the fluorescence of all bacteria was reduced in TSA and BMM media, compared with in TSAB and BMMB media. Both the R/G and the R/RGB values of all bacteria were significantly reduced in growth media without blood (P<0.001). Conclusions: Based on this in vitro study, it can be concluded that red fluorescence of oral bacteria can be affected by growth components, especially blood. Blood-containing medium could be a signifi cant factor influencing red fluorescence of oral bacteria. It can be further hypothesized that bleeding in the oral cavity can increase the red fluorescence of dental plaque.
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정승화 ( Seung-hwa Jeong ),변민지 ( Min-ji Byon ),전은주 ( Eun-joo Jun ) 대한예방치과·구강보건학회 2023 大韓口腔保健學會誌 Vol.47 No.4
Objectives: This study aimed to develop a method for objectively evaluating toothpaste abrasivity, enabling a direct comparison between different toothpastes. Methods: Nine commercially available toothpaste variants were selected, and 8 mm thick acrylic specimens were allocated to each toothpaste treatment group (n=7). A control group without toothpaste was also included. Specimens and toothbrushes were mounted on the V8 Cross brushing machine, and toothpaste (0.05-0.1 g) was applied for 20 strokes under a 200 g load and 1 Hz speed. The surface wear was measured at an absorbance of 600 nm in a UV-Vis spectrophotometer. Specimens were then photographed with a polarized light microscope, and the gray value of the worn brushed part was obtained through image analysis using Image J software. A one-way ANOVA followed by Bonferroni’s post-hoc test was employed for analyzing absorbance and gray value differences among the toothpaste groups. The correlation between absorbance and gray value was assessed using Pearson’s correlation analysis. Results: Significant differences were noted in absorbance and gray values across the toothpaste groups (P<0.05), and a strong correlation was observed between the absorbance and the values from the images analyzed (r=0.948, P<0.001). The wear rankings based on absorbance and image analysis values were mostly the same. Conclusions: This study introduces a direct and objective method for evaluating toothpaste abrasion, offering users objective information on different toothpaste types.
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BLU 및 형광체 코딩용 알루미나 분산액의 제조 및 평가
유정환,정승화,홍경표,문종수,강종봉,Yu, Jeong-Hwan,Jung, Seung-Hwa,Hong, Gyung-Pyo,Mun, Jong-Soo,Kang, Jong-Bong 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.1
The suspension of $Al_2O_3$ which has long-term stability was made by mechanical milling. Thin films were evaluated and made to use as coating materials. A particle size of the suspension manufactured was 98 nm when 2 mt% nitric acid was added. It indicated that viscosity of the suspension is 12 cps and that it had the long-term stability. Thickness which was from 200 nm to 600 nm of the thin films was able to be made by adjusting draw rate and organic additive. Cracks of thin films at room temperature were prevented by adding Ethyl cellulose from 0.5 wt% to 2 wt%. The thin film heated at $500^{\circ}C$ indicated a hydrophilic property against water and an excellent permeability against a visible ray.
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기계적 분쇄방법을 통한 코팅용 알루미나 졸의 제조 및 평가
유정환,정승화,조범래,홍경표,문종수,강종봉,Yu, Jeong-Hwan,Jung, Seung-Hwa,Jo, Bum-Rae,Hong, Gyung-Pyo,Mun, Jong-Soo,Kang, Jong-Bong 한국재료학회 2008 한국재료학회지 Vol.18 No.8
$Al_2O_3$ sol with long-term stability was prepared by mechanical milling. Thin films were evaluated and created for use as coating materials. The particle size of the manufactured sol was 98 nm when 2 wt% of nitric acid was added. This indicates that the viscosity of the sol is 12 cps and that it has long-term stability. The thickness of the thin films, which varied from 100 nm to 500 nm, could be managed by adjusting the draw rate and the amount of an organic additive. A thin film heated to $500^{\circ}C$ indicated a hydrophilic property against water and excellent permeability against a visible ray.
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