CEO칼럼 - 참을 수 없는 행복

한동헌,Han, Dong-Heon 한국대학교육협의회 2012 大學敎育 Vol.178 No.-

대한치과보험학회 회원 일부의 직종에 따른 치과건강보험 인식

한동헌(Han, Dong-Hun),김용진(Kim Yong-Jin) 대한치과보험학회 2014 대한치과보험학회지 Vol.5 No.2

치아우식증의 새로운 생체지표

한동헌(Dong-Hun Han),김민지(Min-Ji Kim),전은주(Eun-Joo Jun),김진범(Jin-Bom Kim) 대한치과의사협회 2012 대한치과의사협회지 Vol.50 No.9

Dental caries is multifactorial local disease which involves destruction of the hard tissues of the teeth by metabolities produces by microorganisms. Recently, there has been growing interest in the role of nitric oxide (NO) and glutathione (GSH) in caries incidence. The aim of the study was to survey the studies reported the association among salivary NO, GSH and dental careis. Three studies reported the association between NO and dental caries. However, the results were contradictory. Only one study showed negative association between GSH and dental caries. In Korea, NO showed negative association with Lactobacilli and GSH showed positive association with dental caries. These observations suggest the possibility that NO and GSH could be new biomarkers for dental caries. However, further study should be needed.

말레산 무수물로 그래프트된 고분자량의 폴리락트산 상용화제가 폴리락트산 기반의 합성목재에 미치는 영향

한동헌(Dong-Heon Han),이종인(Jong In Lee),오승주(Seung-Ju Oh),남병욱(Byeong Uk Nam),배진우(Jin Woo Bae) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.6

Maleic anhydride (MA)와 divinylbenzene (DVB)을 개시제인 di(tert-butyl-perxoyisopropyl)benzene (PK-14)과 함께 이축 압출기에서 용융 그래프팅 반응을 통해 상용화제인 high-molecular-weight maleic anhydride-grafted polylactic acids (HMMA-g -PLA)를 제조하였다. 제조된 HMMA-g -PLA의 특성을 분석하기 위해 Fourier transform infrared (FTIR), Melt index (MI), 그리고 역적정을 실시하였다. HMMA-g -PLA는 DVB의 함량이 증가함에 따라 MA의 그래프팅율은 증가하나 MI는 감소하였는데, DVB의 도입으로 PLA의 β-scission 반응이 억제되어 분자량이 증가되었기 때문이다. HMMA-g -PLA를 사용한 PLA기반 합성목재(wood-plastic composites, WPCs)는 matrix인 PLA에 보강재인 목재와 무기 충전재인 talc를 첨가하여 일축 압출기로 용융 블렌드하였다. 상용화제인 HMMA-g -PLA가 도입된 WPCs는 도입되지 않은 WPCs와 비교하여 더 높은 굴곡강도 및 충격강도를 보였다. 이것은 Scanning electron microscope (SEM) 분석을 통해 HMMA-g -PLA의 첨가로 PLA와 목분과의 계면 결합력이 우수해졌기 때문인 것을 알 수 있었다. 하지만 HMMA-g -PLA의 함량이 높을 때는 WPCs의 기계적 물성을 악화시켰다. 이는 도입된 HMMA-g -PLA 상용화제의 분자량이 PLA 고분자 수지보다 더 낮아 기계적 물성을 감소시킨 것으로 판단하였다. High-molecular-weight maleic anhydride-grafted polylactic acids (HMMA-g -PLA) compatibilizers were prepared by melt grafting in a twin screw extruder using di(tert-butyl-perxoyisopropyl)benzene (PK-14; as initiator), maleic anhydride (MA), and divinylbenzene (DVB). To determine the properties of the prepared HMMA-g -PLA compatibilizers, Fourier transform infrared (FTIR), Melt index (MI), and back-titration analyses were performed. On increasing DVB concentration, grafting yield of HMMA-g -PLA increased but MI decreased because β-scission of PLA was restrained by the DVB, and thus, the molecular weight of HMMA-g -PLA increased. PLA-based wood-plastic composites (WPCs) were prepared using HMMA-g -PLA by melt blending through a single screw extruder. The flexural and impact strengths of WPCs compatibilized with HMMA-g -PLA were greater than those of WPCs produced without HMMA-g -PLA. Scanning electron microscope (SEM) studies indicated that increased mechanical properties were caused by excellent interfacial adhesion between PLA and wood fibers due to the addition of HMMA-g -PLA. However, rather high contents of HMMA-g -PLA reduced the mechanical properties of WPCs. We believe that lower molecular-weight of HMMA-g -PLA added as an compatibilizer, compared with PLA polymer, caused the reduction of mechanical properties.

계면활성제가 도입된 이오노머를 함침시킨 ePTFE기반 강화복합막의 제작과 이들의 PEMFC 특성

한동헌(Dong-Heon Han),오승주(Seung-Ju Oh),이종인(Jong In Lee),배진우(Jin Woo Bae) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.3

고분자 전해질막 연료전지(polymer electrolyte membrane fuel cell, PEMFC)용 ePTFE기반 강화복합막은 이오노머 막에 비해 낮은 가격과 우수한 내구성으로 인해 주목받고 있다. 그러나, 다공성 ePTFE 강화막의 소수성과 이오노머의 친수성 사이의 반발력으로 인해 강화복합막의 불완전한 함침 문제가 발생한다. 이는 ePTFE기반 강화복합막의 오믹 저항과 수소기체투과도를 증가시키기 때문에 PEMFC의 성능과 내구성을 감소시킨다. 본 연구에서는 친수성과 소수성의 반발력을 감소시킴으로써 함침을 개선시키기 위해서 Triton X-100와 Igepal CO-630 계면활성제를 각각 함량별로 이오노머에 도입시켜 용액을 제조하였다. 이를 활용하여 함침을 개선시킨 ePTFE기반 강화복합막을 제작하였으며, 막-전극 접합체(membrane electrode assembly, MEA)로 제작하여 PEMFC에 적용하였다. 계면활성제의 함량이 증가함에 따라서 ePTFE에서 대한 이오노머 용액의 젖음성을 증가되었기 때문에 ePTFE기반 강화복합막의 함침을 개선시켰다. 또한, PEMFC에서 ePTFE기반 강화복합막의 오믹 저항과 수소기체투과도를 감소시킨 것을 확인하였다. 더욱이, Triton X-100에 비해서 우수한 젖음성을 가지는 Igepal CO-630 계면활성제는 ePTFE에 대한 이오노머 용액의 함침을 더욱 개선할 수 있기 때문에 ePTFE기반 강화복합막의 PEMFC 성능과 내구성을 효과적으로 개선시킬 수 있었다. ePTFE-based reinforced composite membranes for polymer electrolyte membrane fuel cells (PEMFCs) have attracted attention because of their higher durability and lower cost than ionomer membranes. On the other hand, repulsion between the hydrophobic ePTFE membrane and hydrophilic ionomer causes incomplete impregnation. This problem deteriorates the performance and durability of PEMFCs owing to the increasing ohmic resistance and hydrogen crossover of the ePTFE-based reinforced composite membrane. This study developed ionomer solutions with Triton X-100 or Igepal CO-630 as surfactants, which can improve impregnation by reducing the repulsion between the hydrophobicity and hydrophilicity. The surfactant-introduced ionomer solutions were impregnated directly on the ePTFE membrane and applied to a membrane electrode assembly (MEA) for PEMFC. The presence of the surfactant improved the impregnation of the ePTFE-based reinforced composite membrane due to the increasing wetting properties of ionomer solutions on the ePTFE membrane and thus reduced the ohmic resistance and hydrogen crossover of PEMFC. In addition, the ionomer with the Igepal CO-630 surfactant showed better wetting properties than that with Triton X-100. Therefore, the introduction of a surfactant into the ePTFE-based reinforced composite membrane was expected to increase the performance and durability of PEMFC effectively.

국민건강증진종합계획에 근거한 영유아 치아우식 관리 방안

한동헌(Han Dong-Hun) 대한치과의사협회 2010 대한치과의사협회지 Vol.48 No.6

We examined progress in oral health of Korean 5 year olds children and dental public health infrastructure since the National Health Promotion Plan 2010 Oral Health Objectives were issued. We summarize trends in the prevalence of dental caries and trends in national public oral health program activities and budget. The Oral Health Objectives were achieved in 2006. Oral health in Korean preschool children improved considerably by improving of lifestyle and consumption of fluoride containing toothpaste. Although the number of public oral health center and the budget of oral health education were increased, the impact of public oral health program for preschool children was not influential. New oral health program for infants such as fluoride varnish application and strengthening of existing public oral health program should be performed for continuing improvement of oral. health in Korea.

제3차 저출산·고령사회 기본계획 수립 배경과 구강보건의 의의

한동헌(Han Dong Hun) 대한치과의사협회 2016 대한치과의사협회지 Vol.54 No.6

Korean government enacted the 1st Basic Plan for Low Fertility and Population Ageing in 2005 due to the long-lasting ultralow birth rate. Based on the Act, Korean government set up a step-by-step strategic goal and establish a basic plan, every five years, to achieve the sustainable development of society corresponding to low fertility and aging society. Over the past decade, the 1st Basic Plan for Low Fertility and Population Ageing ( 2006-2010 ) and the 2nd Basic Plan for Low Fertility and Population Ageing ( 2011-2015 ) was executed. This year, based on the achievements and limitations of the 1st and 2nd Basic Plan, the 3rd Basic Plan for Low Fertility and Population Ageing begins. In this manuscript, I discuss the background of the 3rd Basic Plan and its significance in oral health area.

시판 차 음료 속에 함유된 불소의 농도 측정 및 연령별 불소섭취량 추정

한동헌 ( Dong Hun Han ),이운정 ( Un Jung Lee ),김동현 ( Dong Hyun Kim ),김민지 ( Min Ji Kim ),황수정 ( Su Jung Hwang ),김진범 ( Jin Bom Kim ) 대한예방치과·구강보건학회 2010 大韓口腔保健學會誌 Vol.34 No.3

Objectives. The purpose of this study was to analyze the fluoride concentrations of tea drinks which were commercially available in Korea in 2009 and to predict amount of daily fluoride intake from tea drink according to different age groups. Methods. The fluoride concentrations of 20 kinds of tea drinks were assessed by a fluoride ion selective electrode. The estimates of daily fluoride intake were assumed by Dietary Reference Intakes for Koreans 2005. Results. The fluoride concentrations of tea drinks were 0.03~1.72 ppm (mean 0.51 ppm). The calculated amount of daily fluoride intake which were supposed to drink all the sufficient water intake by tea drink of 1.72 ppm fluoride were over maximum intake of fluoride under 9 years olds and over sufficient intake of fluoride in all age groups. Those of 0.51 ppm fluoride were under maximum intake of fluoride in all age groups and over sufficient intake of fluoride under 5 months olds infants. Conclusions. Based on this study, most of the tea drink in Korea contained the appropriate concentration of fluoride. However, consuming some tea drink available in Korean market in large quantities may lead to exposion to a high amount of fluoride which may cause dental fluorosis in infants and young children. Although most of tea drinks are safer to consume, fluoride concentrations of some tea drinks are too low for caries prevention. In countries such as Korea where tea is traditionally consumed, the fluoride concentration and daily safety precautions should be indicated on tea products.

한국노인에서 저작불편감과 복합만성질환의 연관성

한동헌(Dong-Hun Han) 대한치과의사협회 2013 대한치과의사협회지 Vol.51 No.9

To assess the association between oral health and general health, this study examined the relationship between chewing difficulty and twelve chronic health conditions such as hypertension, hyperlipidemia, diabetes, cerebro- and cardiovascular disease, musculoskeletal disease, respiratory disease, eye/nose/throat disease, stomach/intestinal ulcer, renal dysfunction, thyroid disease, depression, and cancer in Korea. The study population was 3,066 elders aged 65 years old and more from the fourth Korean National Health and Nutrition Examination Survey. Chewing difficulty was measured on a 5-point Likert scale. Chronic conditions were assessed by self-reported questionnaire. Confounders were age, gender, education, income, smoking, drinking, and obesity. Chi-square test, general linear model, and multiple logistic regression model were done with complex sampling design. Musculoskeletal disease (adjusted odds ratio=1.33), respiratory disease (adjusted odds ratio=1.52), and cancer (adjusted odds ratio=1.58) were independently associated with chewing difficulty. Multiple chronic conditions with more than 4 chronic disease showed significant association with chewing difficulty (adjusted odds ratio=1.37).

고체산화물 연료전지용 코발트 코팅된 460FC계 금속분리판의 고온산화특성

한동헌(Dong-Heon Han),오승주(Seung-Ju Oh),이종인(Jong In Lee),배진우(Jin Woo Bae) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.2