Impact of Nonpharmacological Interventions on Severe Acute Respiratory Infections in Children: From the National Surveillance Database

Yoon Yoonsun,Lee Hye Sun,Yang Juyeon,Gwack Jin,Kim Bryan Inho,Cha Jeong-ok,Min Kyung Hoon,Kim Yun-Kyung,Shim Jae Jeong,Lee Young Seok 대한의학회 2023 Journal of Korean medical science Vol.38 No.40

Background: Nonpharmacological interventions (NPIs) reduce the incidence of respiratory infections. After NPIs imposed during the coronavirus disease 2019 pandemic ceased, respiratory infections gradually increased worldwide. However, few studies have been conducted on severe respiratory infections requiring hospitalization in pediatric patients. This study compares epidemiological changes in severe respiratory infections during pre-NPI, NPI, and post-NPI periods in order to evaluate the effect of that NPI on severe respiratory infections in children. Methods: We retrospectively studied data collected at 13 Korean sentinel sites from January 2018 to October 2022 that were lodged in the national Severe Acute Respiratory Infections (SARIs) surveillance database. Results: A total of 9,631 pediatric patients were admitted with SARIs during the pre-NPI period, 579 during the NPI period, and 1,580 during the post-NPI period. During the NPI period, the number of pediatric patients hospitalized with severe respiratory infections decreased dramatically, thus from 72.1 per 1,000 to 6.6 per 1,000. However, after NPIs ceased, the number increased to 22.8 per 1,000. During the post-NPI period, the positive test rate increased to the level noted before the pandemic. Conclusion: Strict NPIs including school and daycare center closures effectively reduced severe respiratory infections requiring hospitalization of children. However, childcare was severely compromised. To prepare for future respiratory infections, there is a need to develop a social consensus on NPIs that are appropriate for children.

Influenza Vaccine Effectiveness in Children at the Emergency Department during the 2018-2019 Season: the First Season School-aged Children Were Included in the Korean Influenza National Immunization Program

Yoonsun Yoon,Joon-sik Choi,MiRan Park,Hyun Cho,Minsu Park,Hee Jae Huh,Yae-Jean Kim,Meong Hi Son 대한의학회 2021 Journal of Korean medical science Vol.36 No.10

Background: For the 2018–2019 season, the national influenza immunization program expanded to cover children aged from 6 months to 12 years in Korea. This study aimed to analyze vaccine effectiveness (VE) against influenza in children visiting the pediatric emergency room at a tertiary hospital during the 2018-2019 season. Methods: Patients tested for influenza antigens from October 1st 2018 to May 31st 2019 at the pediatric emergency room of Samsung Medical Center were included. Patients' influenza antigen test results, influenza vaccination history, and underlying medical conditions were reviewed retrospectively. VE was estimated from the test-negative design study. Results: Among the 2,901 visits with influenza test results 1,692 visits of 1,417 patients were included for analysis. Among these 1,417 patients, 285 (20.1%) were positive (influenza A, n = 211, 74.0%; influenza B, n = 74, 26.0%). The VE in all patients was 36.4% (95% confidence interval [CI], 13.9 to 53.1). The VE for influenza A was 37.6% (95% CI, 12.6 to 55.5) and VE for influenza B was 24.0% (−38.5 to 58.3). The VE in the age group 6 months to 12 years was significant with a value of 35.6% (95% CI, 10.5 to 53.7); it was not statistically significant in the age group 13 to 18 years. In a multivariate logistic regression model, patients who received an influenza vaccination were less likely to get influenza infection (OR, 0.6; 95% CI, 0.4 to 0.8; P = 0.001), with significant confounding factors such as age group 13 to 18 years (OR, 0.5; 95% CI, 0.3 to 0.8; P = 0.003) and underlying hematology-oncology disease (OR, 0.3; 95% CI, 0.1 to 0.6; P = 0.002). Conclusion: We report moderate effectiveness of influenza vaccination in previously healthy children aged from 6 months to 12 years in the 2018-2019 season.

Stepwise School Opening and an Impact on the Epidemiology of COVID-19 in the Children

Yoonsun Yoon,김경란,박환희,김소영,김예진 대한의학회 2020 Journal of Korean medical science Vol.35 No.46

Background: Data on severe acute respiratory syndrome coronavirus-2 transmission from a pediatric index patient to others at the school setting are limited. Epidemiological data on pediatric coronavirus disease 2019 (COVID-19) cases after school opening are warranted. Methods: We analyzed data of the pediatric patients with COVID-19 collected from the press release of the Korea Centers for Disease Control and Prevention. Information on the school opening delay and re-opening policies were achieved from the press release of the Korean Ministry of Education. Results: The school openings were delayed three times in March 2020. Online classes started from April 9, and off-line (in-person) classes started from May 20 to June 8 at four steps in different grades of students. There was no sudden increase in pediatric cases after the school opening, and the proportion of pediatric cases among total confirmed cases in the nation around 7.0%. As of July 31, 44 children from 38 schools and kindergartens were diagnosed with COVID-19 after off-line classes started. More than 13,000 students and staffs were tested; only one additional student was found to be infected in the same classroom. The proportions of pediatric patients without information on infection sources were higher in older age groups than in younger age groups (17.4% vs. 52.4%, P = 0.014). In the younger age group, 78.3% of children were infected by family members, while only 23.8% of adolescents in the older age group were infected by family members (P < 0.001). Conclusion: Korea had a successful transition from school closure to online and off-line school opening, which did not cause significant school-related outbreak among the pediatric population.

Synthesis and Electroresponse Activity of Porous Polypyrrole/Silica-Titania Core/Shell Nanoparticles

Yoon, Chang-Min,Cho, Kyung Hee,Jang, Yoonsun,Kim, Jungwon,Lee, Kisu,Yu, Haejun,Lee, Seungae,Jang, Jyongsik American Chemical Society 2018 Langmuir Vol.34 No.51

<P>Inverted conducting polymer/metal oxide core/shell structured pPPy/SiO<SUB>2</SUB>-TiO<SUB>2</SUB> nanoparticles were prepared as electrorheological (ER) materials using sequential experimental methods. The core was synthesized via the low-temperature self-assembly of PPy and SiO<SUB>2</SUB> materials, and the outer TiO<SUB>2</SUB> shell was easily coated onto the core part using a sol-gel method and a titanium isopropoxide precursor. Sonication-mediated etching and redeposition were employed to etch out SiO<SUB>2</SUB> portions from the core part to blend with TiO<SUB>2</SUB> shells. Each step in nanoparticle synthesis involved morphological and physical changes to the surface area and porosity, with subsequent changes in the intrinsic properties of the materials. Specifically, the electrical conductivity and dielectric properties were successfully altered. The final pPPy/SiO<SUB>2</SUB>-TiO<SUB>2</SUB> nanoparticle configuration was optimized for ER applications, offering low electrical conductivity, high dielectric properties, and increased dispersion stability. pPPy/SiO<SUB>2</SUB>-TiO<SUB>2</SUB> nanoparticles exhibited 24.7- and 2.7-fold enhancements in ER performance compared to that of PPy-SiO<SUB>2</SUB> and PPy-SiO<SUB>2</SUB>/TiO<SUB>2</SUB> precursor nanoparticles, respectively. The versatile method proposed in this study for the synthesis of inverted conducting polymer/metal oxide core/shell nanoparticles shows great potential for the development of custom-designed ER materials.</P> [FIG OMISSION]</BR>

Dual electric and magnetic responsivity of multilayered magnetite-embedded core/shell silica/titania nanoparticles with outermost silica shell

Yoon, Chang-Min,Jang, Yoonsun,Lee, Seungae,Jang, Jyongsik The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.38

<P>Multilayered magnetite-embedded core/shell silica/titania (SiO2/TiO2) nanoparticles with an outermost silica shell (SiO2/TiO2@Fe3O4/SiO2) were synthesized and used to develop stimuli-responsive smart fluids. Benefiting from the incorporation of the various materials, these smart fluids demonstrated electrorheological (ER) and magnetorheological (MR) activities under applied external electric (<I>E</I>) and magnetic (<I>H</I>) fields, respectively, and electromagnetorheological (EMR) characteristics with the simultaneous application of <I>E</I> and <I>H</I> fields. The inner SiO2/TiO2 core nanoparticles, embedded Fe3O4 nanoparticles and the outer SiO2 shell served as electroresponsive, magnetoresponsive and preventative materials toward corrosion, sedimentation and aggregation. The EMR performance of these fluids depended on the direction of the applied <I>E</I> and <I>H</I> fields. Notably, a 6.6-fold enhancement in EMR activity was observed with parallel application of <I>E</I> and <I>H</I> fields compared to perpendicular direction. This study demonstrates an effective approach to precisely and spatially control the rheological/mechanical properties of dual-responsive smart fluids <I>via</I> both field-induced and directional control of external fields.</P>

Smart Fluid System Dually Responsive to Light and Electric Fields: An Electrophotorheological Fluid

Yoon, Chang-Min,Jang, Yoonsun,Noh, Jungchul,Kim, Jungwon,Jang, Jyongsik American Chemical Society 2017 ACS NANO Vol.11 No.10

<P>Electrophotorheological (EPR) fluids, whose rheological activity is dually responsive to light and electric fields (E fields), is formulated by mixing photosensitive spiropyran-decorated silica (SP-sSiO(2)) nanoparticles with zwitterionic lecithin and mineral oil. A reversible photorheological (PR) activity of the EPR fluid is developed via the binding and releasing mechanism of lecithin and merocyanine (MC, a photoisomerized form of SP) under ultraviolet (UV) and visible (VIES) light applications. Moreover, the EPR fluid exhibits an 8 fold higher electrorheological (ER) performance compared to the SP-sSiO(2) nanoparticle-based ER fluid (without lecithin) under an E field, which is attributed to the enhanced dielectric properties facilitated.by the binding of the lecithin and SP molecules. Upon dual application of UV light and an E field, the EPR fluid exhibits high EPR performance (ca. 115.3 Pa) that far exceeds its separate PR (ca. 0.8 Pa) and ER (ca. 57.5 Pa) activities, because of the synergistic contributions of the PR and ER effects through rigid and fully connected fibril-like structures. Consequently, this study offers a strategy on formulation of dual-stimuli responsive smart fluid systems.</P>

Enhanced Electrorheological Performance of Mixed Silica Nanomaterial Geometry

Yoon, Chang-Min,Jang, Yoonsun,Noh, Jungchul,Kim, Jungwon,Lee, Kisu,Jang, Jyongsik American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.41

<P>The mixed geometrical effect on the electror-heological (ER) activity of bimodal ER fluids was investigated by mixing SiO2 spheres and rods of different dimensions. To, gain an in-depth understanding of the mixed geometrical effect, 12 bimodal ER fluids were prepared from 4 sizes of SiO2 spheres (50, 100, 150, and 350 nm) and 3 types of SiO2 rods with different aspect ratios (LID = 2, 3, and 5). Five concentrations of SiO2 spheres and rods were created for each bimodal ER fluid, resulting in a total of 60 sets of comprehensive ER measurements. Some bimodal ER fluids exhibited enhanced ER performance, as high as 23.0%, compared to single SiO2 rod-based ER fluids to reveal the mixed geometrical effect of bimodal ER fluids. This interesting experimental result is based on the structural reinforcement provided by spheres to fibrillated rod materials, demonstrating the mixed geometrical effect on ER activity.</P>

유전 알고리즘을 적용한 토지이용 최적화 배분 연구 - 양평군 양평읍 일대를 대상으로 -

박윤선 ( Yoonsun Park ),이동근 ( Dongkun Lee ),윤은주 ( Eunjoo Yoon ),모용원 ( Yongwon Mo ),임지훈 ( Jihun Leem ) 한국환경영향평가학회 2017 환경영향평가 Vol.26 No.1

지속가능한 발전은 도시의 효율적인 개발과 경제, 사회, 환경적 측면의 보전을 목표로 하기 때문에 중요하다. 그러나 우리나라의 빠른 도시화로 경제적 발전은 이루었지만 자원의 비효율적인 배분현상을 경험하게 되었고 이는 토지이용 배분도 예외가 아니다. 토지이용 배분의 문제가 어려운 이유는 다양한 목적을 고려해야하기 때문이며 이는 다목적 최적화의 방법에서 그 해결책을 찾을 수가 있다. 본 연구에서는 생태적으로 보존이 잘 되어있으며 인구 증가가 일어나고 있는 경기도 양평지역의 양평읍과 그 일대를 대상지로 선정하였다. 그리고 넓은 공간 탐색에 유리하고 토지이용 배분의 문제에서 널리 사용되고 있는 유전 알고리즘을 사용하였다. 유전알고리즘(GA)는 더 좋은 자손을 얻기 위하여 염색체의 교차 및 돌연변이의 과정을 거치는 적자생존의 원리가 작용하는 진화의 단계가 그 출발점이다. 본 연구는 변이의 방식에 변화를 주었으며 공간적 목적, 토지이용 전환 최소화, 생태계 보전 최대화, 경제적 이익 최대화라는 네 가지 목적과 특정 토지이용의 면적제한과 고정지역 설정이라는 제약요건을 두고 최적 안을 도출해내었다. 생태적으로 보존시켜야 할 곳에는 시가지가 형성되지 않았고, 시가지 면적 증가율이 높은 결과는 최적화의 방향인 `경제적 이익의 최대화`라는 점과 상응하였다. 적합도 값이 최소인 지점이 수렴지점임을 고려했을 때, 1500세대 부근에서 최적화가 일어났음을 알 수 있었다. 본 연구의 결과는 양평읍과 그 일대에 적용시킬 수 있는 효과적인 지원방안을 마련하는데 도움이 될 수 있을 것으로 판단된다. Sustainable development is important because the ultimate objective is efficient development combining the economic, social, and environmental aspects of urban conservation. Despite Korea`s rapid urbanization and economic development, the distribution of resources is inefficient, and land-use is not an exception. Land use distribution is difficult, as it requires considering a variety of purposes, whose solutions lie in a multipurpose optimization process. In this study, Yangpyeong-eup, Yangpyeong, Gyeonggi-do, is selected, as the site has ecological balance, is well-preserved, and has the potential to support population increases. Further, we have used the genetic algorithm method, as it helps to evolve solutions for complex spatial problems such as planning and distribution of land use. This study applies change to the way of mutation. With four goals and restrictions of area, spatial objectives, minimizing land use conversion, ecological conservation, maximizing economic profit, restricting area to a specific land use, and setting a fixed area, we developed an optimal planning map. No urban areas at the site needed preservation and the high urban area growth rate coincided with the optimization of purpose and maximization of economic profit. When the minimum point of the fitness score is the convergence point, we found optimization occurred approximately at 1500 generations. The results of this study can support planning at Yangpyeong-eup.ausative relationship between the perception of improving odor regulation and odor acceptance.

문항반응이론 가정검증을 기반으로 한 대안적 모수추정모형 비교연구

윤지영(Yoon, Jiyoung),이윤선(Lee, Yoonsun) 한국교육평가학회 2016 교육평가연구 Vol.29 No.1

본 연구는 PISA 2009 읽기검사의 문항 특성과 피험자 특성을 추정하기 위해 문항반응이론을 적용한 연구로, 문항반응이론 가정검증을 바탕으로 PISA 2009 읽기 검사에 가장 적절한 대안적 모수추정모형을 선택, 적용하고자 하였다. 이를 위해 먼저 PISA 2009 읽기검사의 총 13개 검사소책자의 단일차원성 가정 만족여부를 검증한 결과, 모든 검사소책자에서 단일차원성이 위배되었고, 지역독립성 가정 검증 결과, 검사소책자 중 8개가 지역독립성을 위배한 것으로 확인되었다. 검사의 가정 위배에 따라 단일차원성만 위배된 경우에는 bi-factor IRT 모형이, 단일차원성과 지역독립성이 모두 위배된 경우에는 testlet 기 반 모형이 모수추정에 가장 적합한 것으로 나타났다. 연구 결과는 문항반응이론 적용을 위해 전제되어야 하는 가정 위배 상황에 따라 다른 대안적 모수추정모형이 적합할 수 있음을 제안하고 있으며, 이는 검사의 단일차원성과 지역독립성 위배에 대한 확인과 더불어 그에 맞는 대안적 모수추정모형을 고려해야할 필요가 있음을 시사한다. This study investigated the most appropriate alternative IRT parameter estimation models when the IRT assumptions are not met. For this study, the PISA 2009 reading test was used to confirm IRT assumptions, and to compare the alternative IRT models based on the results of the assumption satisfaction. The results of testing the assumptions using the actual test showed that, all of the 13 test booklets were in violation of the unidimnsionality assumption and eight of the test booklets unsatisfied the local independence assumption. Specifically, bi-factor IRT model was the most appropriate when the unidimensionality assumption was violated, and testlet based model was appropriate regardless of the item length or the item clusters when the principles of unidimensionality and local independence assumptions were violated simultaneously. It is significant that the appropriate type of alternative IRT models differ based on which IRT assumptions are violated. When the large scale academic performance tests violate unidimensionality and local independence assumptions, the alternative IRT models can be considered for better parameter estimation. As this study shows, it is necessary to estimate alternative IRT models by going through the process of anticipating the possibility of violation of IRT assumptions due to the test forms and domains of their contents. It is expected that such a process will provide the basis for applying the IRT more precisely in order to estimate the capability of item and person characteristics.

가중 군집 모델을 활용한 공동주택 입지 분석에 관한 연구

황윤선(Yoonsun Hwang),주병준(Byeongjun Joo),윤혜선(Hyeseon Yoon),박종대(Jongdae Park),이형진(Hyungjin Lee),강유(U Kang) 한국정보과학회 2022 한국정보과학회 학술발표논문집 Vol.2022 No.06