Effects of outdoor air pollution on children with allergic rhinitis

The global worsening of air pollution has decreased the quality of life. Air pollutants can induce oxidative stress, epigenetic changes, and alterations to microRNA expression in the airway and skin, leading to immune dysregulation. Previous epidemiological studies suggest a strong association between outdoor environmental pollution and childhood allergic disease, especially allergic rhinitis (AR). Moreover, traffic-related air pollution has increased the severity and incidence of AR, and heavy traffic has been associated with an increased prevalence of AR. Thus, this review aimed to define outdoor environmental pollution and clarify the mechanisms by which air pollutants aggravate AR. In addition, we performed a systematic review and meta-analysis to summarize the findings of several domestic and international epidemiological and clinical studies about the effects of air pollution on AR in children.ope

The incidence and risk factors of extrapulmonary manifestations in Mycoplasma pneumoniae pneumonia

Purpose Mycoplasma pneumoniae pneumonia (MP) is a major cause of community-acquired pneumonia (CAP) in children and is associated with extrapulmonary manifestations (EPM). The incidence and risk factors for EPM in children are unknown. Methods This was a retrospective study involving 65,243 pediatric patients with CAP between 2010 and 2015 at 23 nationwide hospitals in South Korea. Medical records were reviewed to collect information regarding the clinical characteristics, radiological results, and laboratory findings. Logistic regression with multivariate analysis was performed to evaluate the risk factors associated with EPM in MP. Results The incidence of EPM was 23.9%, including elevation of liver enzymes (18.1%), mucocutaneous manifestations (4.4%), proteinuria (4.1%), cardiovascular and neurological manifestations (0.4%), hematologic manifestations (0.2%), and arthritis (0.2%). Statistical analysis showed that mucocutaneous manifestations significantly increased with elevated alanine aminotransferase (adjusted odds ratio [aOR], 3.623; 95% confidence interval [CI], 1.933-6.790) and atopic sensitization (aOR, 2.973; 95% CI, 1.615–5.475) and decreased with respiratory virus coinfection (aOR, 0.273; 95% CI, 0.084–0.887). Elevated liver enzymes were significantly associated with elevated lactate dehydrogenase (aOR, 3.055; 95% CI, 2.257–4.137), presence of pleural effusion (aOR, 2.635; 95% CI, 1.767–3.930), and proteinuria with respiratory virus coinfection (aOR, 2.245; 95% CI, 1.113–4.527). Conclusion Approximately 24% of pediatric patients with MP had various EPM. As the risk factors associated with each EPM were different, it is necessary to evaluate the various clinical aspects and findings of MP to predict and prepare for the occurrence of EPM.ope

Adverse reactions to coronavirus disease 2019 vaccines in children and adolescents

The incidence of coronavirus diseases 2019 (COVID-19), including severe cases, has been increasing in both children and adolescents with the spread of the delta variant. COVID-19 vaccines have been identified to be effective in the prevention of COVID-19 transmission in children and adolescents and keeping schools open. However, adverse reactions associated with COVID-19 vaccination in children and adolescents contribute to parents’ hesitation to proceed with vaccination, especially due to serious, albeit rare, reactions. The results from COVID-19 vaccine clinical trials on the safety and efficacy of COVID-19 vaccines in children and adolescents are promising in terms of their effects on COVID-19 infection prevention. In the present study, we summarize the adverse reactions of COVID-19 vaccines in children and adolescents, based on the clinical trials, mainly including Pfizer-BioNTech and Moderna COVID-19 vaccines. In the Pfizer-BioNTech COVID-19 clinical trials, the most common local adverse reaction was pain at the injection site in 74.1%–86%, depending on age, and the most common systemic adverse reaction was fatigue, followed by headache, myalgia, diarrhea, and fever with differences in the distribution according to age. There was no severe adverse reaction related to any COVID-19 vaccine in children and adolescents during the study period. In the mass vaccination program of COVID-19 in children and adolescent, myocarditis has rarely been diagnosed after COVID-19 vaccination, which most commonly occurred in boys after the second dose. Currently, Pfizer-BioNTech COVID-19 vaccines can be safely recommended in children and adolescents for the prevention of COVID-19 infection and the reduction in COVID-19 severity.ope

KAAACI Allergic Rhinitis Guidelines: Part 1. Update in Pharmacotherapy

The prevalence of allergic rhinitis (AR) and the socioeconomic burden associated with the medical cost and quality of life (QOL) of AR have progressively increased. Therefore, practical guidelines for the appropriate management of AR need to be developed based on scientific evidence while considering the real-world environment, values, and preferences of patients and physicians. The Korean Academy of Asthma, Allergy and Clinical Immunology revised clinical guidelines of AR to address key clinical questions of the management of AR. Part 1 of the revised guideline covers the pharmacological management of patients with AR in Korea. Through a meta-analysis and systematic review, we made 4 recommendations for AR pharmacotherapy, including intranasal corticosteroid (INCS)/intranasal antihistamine (INAH) combination therapy, oral antihistamine/INCS combination therapy, leukotriene receptor antagonist treatment in AR patients with asthma, and prophylactic treatment for patients with pollen-induced AR. However, all recommendations are conditional because of the low or very low evidence of certainty. Well-designed and strictly executed randomized controlled trials are needed to measure and report appropriate outcomes. Copyright © 2023 The Korean Academy of Asthma, Allergy and Clinical Immunology.ope

디젤 엔진의 성능과 배기 최적화를 위한 연소 디자인 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 기계공학부, 2021.8. 이광호.최근 내연기관 성능향상을 위한 연구는 연비, 배출량, 소음, 진동 등의 측면에 초점이 맞춰지고 있다. 연비는 지구온난화에 영향을 준 이산화탄소 배출 감소와 관련이 있다. 또한, 디젤 연소로 인한 질소산화물과 그을음 배출은 인간의 건강에 해로우며 생명까지도 위협한다. 배기 가스의 유해성은 많은 나라들의 정부들로 하여금 차량 배출 규제를 엄격하게 만들도록 동기를 부여하고 있다. 최근에는 실험실의 인증치와 도로의 실제 배출량 수준 간의 차이를 고려해 Real-driving emissions 규제가 시행됐다. 소음 공해는 또한 인간과 공중 보건 문제의 관점에서 중요한 주제이다. 엔진에서 발생하는 연소 소음은 엔진 변수 및 연소 특성에 의해 영향을 받는 실린더 압력 배출에 따라 달라진다. 적절한 분사 전략 또는 연소 형태는 원하는 연소 소음 수준을 만족하도록 최적화할 수 있다. 엔진 개발 과정 중에 연비, 배기 배출물 및 소음의 각 성능을 최적화하기 위한 많은 노력과 시간이 소모된다. 최적의 성능을 얻으려면 연소 및 엔진 작동 변수를 최적화하기 위해 많은 실험이 필요하다. 실험 없이 엔진 성능을 최적화하기 위해 전산유체역학 시뮬레이션을 수행하려면 높은 계산 비용이 필요하다. 따라서, 계산 비용이 낮은 0-D 연소 최적화 방법론을 개발하는 것이 중요하다. 이전 연구들에 의한 0-D 연소 최적화 방법은 분사 전략 또는 엔진 변수를 최적화했다. 결과로 도출되는 연소는 기존 연소 형상의 범위 내에 있으며 연소 형상의 다양성 측면에서 실험적으로 변수를 최적화하는 방법과 다를 바 없다. 본 연구에서는 원하는 성능을 입력으로, 최적 연소 및 연소 변수를 출력으로 도출되는 연소 디자인 방법론을 개발하였다. 첫 번째 단계로 엔진 실험을 수행하여 베이스 조건, EGR 스윙, 흡기 온도 및 냉각수 온도 스윙 조건에서의 연비 및 배기 배출의 기본 성능을 평가하였다. 이 결과는 연소 디자인에 활용되는 0-D soot 모델 수립과 최적화 과정에서 초기 조건으로 사용되었다. Soot 생성 모델은 lift-off length에서 당량비를 계산하는 단순화된 스프레이 모델을 기반으로 했다. Lift-off length에서의 당량비는 그을음 형성 모델의 주요 요인 중 하나로 사용되었다. 연소 디자인 과정에서 IMEP는 연비를 대변하는 인자로 사용되었다. 연소 소음 평가에는 연소 소음 지수가 사용되었다. NOx 배출량 예측에는 이전 연구로부터 개발된 0-D NOx 모델이 적용되었다. 연소 디자인 방법론에서, 실린더 내 압력 계산에 필요한 변수는 흡기 압력, 람다 및 질량 연소율이었다. 질량 연소율은 기존에 널리 사용되는 위베 함수와 연소상에 대한 새로운 접근법으로 다항식 함수를 사용하여 결정되었다. 실린더 내 공기의 질량과 EGR율은 초기 조건으로 결정된 흡기 압력, 온도, 람다 및 화학 반응 방정식으로 계산되었다. 연소 중의 기체 조성비는 polytropic 지수 및 여러 열역학적 변수의 계산을 위해 계산되었다. 실린더 내 압력은 polytropic 과정과 열 발생률으로 계산되었다. 최적화 과정에서 연소 디자인 방법에 사용된 최적화 알고리즘은 제한된 비선형 다변량 함수(Interior-point 기법)와 입자 군집 최적화의 최소값이었다. 경계 조건과 제약 조건은 최적화 과정의 효율적인 iteration을 위해 결정되었다. 최적화를 위한 목적 함수의 기본 형태는 입력으로 사용된 원하는 성능을 가지는 특정한 연소를 찾을 수 있게 했다. 목표 성능을 최대화하는 다양한 디자인 목적에 따라 목표 함수는 변형되어 사용되었다. 연소 디자인의 결과는 다양한 운전 영역에서 MFB와 목적 함수에 따라 연구되었다. WLTP 운전 영역에서 정상 상태 연소들을 디자인하여 연소 디자인 방법론을 WLTP에 적용하였다. 적용 결과, WLTP 중 연료 소모량은 4.7% 감소되었다. NOx와 soot 배출은 각각 44.7%와 60.7%의 감소율을 보였다. 본 연구에서는 원하는 성능의 연소를 도출하는 0-D 연소 시뮬레이션 및 최적화 방법을 제공하였다. 이 연구는 원하는 성능 혹은 최적화된 성능을 가지는 연소상을 열역학적인 조건들과 함께 제시할 수 있어 이를 바탕으로 기존의 연구 방법과 다른 목표 연소를 구현하기 위한 엔진과 연소 전략 개발 방향을 제시할 수 있다.Recently, the researches for improving the performance of the internal combustion engines have been focused on the respect of thermal efficiency, emissions, noise and vibration. The thermal efficiency is related with decreasing carbon dioxide (CO2) emission that has affected global warming. Also, nitrogen oxides (NOx) and soot emissions from diesel combustion are harmful for human. The harmfulness of exhaust gases has motivated governments of many countries to make vehicle emission regulations stringent. Recently, real-driving emissions (RDE) regulation was enforced, considering the discrepancy between the certified values in laboratory and the actual emission levels on the road. Noise pollution is also important in the perspective of human and public health problem. The combustion noise from the engine depends on the cylinder pressure excitation, which is affected by the engine parameters and combustion characteristics. Proper injection strategies or combustion shape can be optimized to meet the desired combustion noise level. The engine development process takes a lot of effort and time to optimize each performance of thermal efficiency, emissions and noise. To achieve desired optimal performance, many trials and errors and experiments are required to optimize combustion and engine operating parameters. As an optimization tool, computational fluid dynamics (CFD) simulation needs substantial calculation cost. Thus, it is important to develop 0-D combustion optimization methodology that has low calculation cost. Previously studied 0-D combustion optimization methods have been optimized the injection strategy or engine parameters. The resulting combustion comes out of a narrow range and it is similar to the methodology of optimizing variables experimentally in terms of diversity of combustion. In this study, the combustion design methodology was developed that used the desired performance as input and derived combustion and combustion parameters as outputs in a diesel engine. The thermal efficiency, noise and emissions were needed to be calculated by 0-D combustion simulation for the combustion optimization. As a one of emission models, the 0-D soot model was developed through cooperative research with Youngbok Lee. The engine test that evaluated the soot emission by EGR rate, intake and coolant temperature was conducted to develop the 0-D soot model and acquire initial conditions for combustion design. The soot formation model was based on the simplified spray model to calculate the equivalence ratio at lift-off length. The equivalence ratio at the lift-off length was used as a one of the main factor for the soot formation model. In the combustion design process, IMEP represented the thermal efficiency. For the combustion noise evaluation, the combustion noise index was used. The 0-D NOx model from previous research was applied to estimate NOx emission. In the combustion design methodology, the initial parameters for constructing in-cylinder pressure were intake pressure, lambda and the mass faction burned. The MFB was determined by using Wiebe function and polynomial function as new approach to combustion phase. The mass of in-cylinder air and EGR rate were calculated from intake pressure, temperature, lambda, that were determined as initial conditions, and the chemical reaction equation. Compression and expansion strokes were assumed as polytropic process. The gas compositions during the combustion were calculated for calculation of polytropic index and other thermodynamic parameters. The in-cylinder pressure was calculated by the heat release rate and polytropic process with the estimated polytropic index. In the optimization process, the optimization algorithms used in the combustion design method were a minimum of constrained nonlinear multivariable function (interior-point) and particle swarm optimization. MATLAB was used as the optimization tool. The boundary conditions and constraints were determined for efficient iteration in optimization process. The base form of objective function for optimization allowed to find specific combustion of desired performance that was used as input. The objective functions for various design concepts were used in maximizing target performance. The results of combustion design were investigated by objective function and MFB function type at various operation point. The combustion design method was applied to WLTP by designing the steady points in WLTP operation region. The fuel consumption during WLTP decreased by 4.6% compared to experimental result The NOx and soot emissions could be reduced by 44.7% and 60.7%. In this study, the 0-D combustion simulation and optimization method that derived the combustion of desired performance were provided. This research can contribute to provide combustion shape with desired or optimized performance in combination with thermodynamic conditions, suggesting the development process different from existing research methods of engine and combustion strategies for target combustion.Chapter 1. Introduction 1 1.1 Background 1 1.2 Literature Review 8 1.2.1 Combustion noise model 8 1.2.2 NOx emission model 11 1.2.3 Soot emission model 13 1.2.4 Combustion optimization 18 1.3 Research Objectives and Contributions 28 1.4 Structure of the Thesis 29 Chapter 2. Experimental Apparatus 31 2.1 Experimental Setup 31 2.1.1 Test engine 31 2.1.2 Test cell and data acquisition systems 31 2.1.3 Emission measurement systems 32 2.1.4 Engine operating conditions 34 Chapter 3. Semi-physical 0-D Soot Model 46 3.1 Simplified Spray Model 46 3.1.1 Spray model description 46 3.1.2 Liquid length calculation 48 3.1.3 Laminar flame speed model 50 3.1.4 The equivalence ratio at the lift-off length 53 3.2 Semi-physical 0-D Soot Model 64 3.2.1 Soot formation model 64 3.2.2 Soot oxidation model 65 3.2.3 The model validation 68 Chapter 4. Other Models for Thermal Efficiency, Noise and NOx Emission 74 4.1 Thermal Efficiency 74 4.2 Noise – Combustion Noise Index (CNI) 74 4.3 The NOx Estimation Model 78 Chapter 5. Combustion Design Methodology 81 5.1 Concept of Combustion Design Method 81 5.2 Process of Constructing Combustion Pressure 86 5.2.1 Mass fraction burned and heat release rate 86 5.2.2 Calculation of in-cylinder air flow and EGR rate 95 5.2.3 Gas composition during the combustion process 102 5.2.4 Polytropic index and constructing cylinder pressure 103 5.2.5 Calculation of the fuel injection timing 107 5.3 Optimization Methodology 113 5.3.1 Optimization algorithms 113 5.3.2 Boundary conditions and constraints 116 5.3.3 Determination of the objective function 121 Chapter 6. Results of Combustion Design 131 6.1 Results from Base Objective Function 131 6.1.1 Low load: 1500 rpm, BMEP 4 bar 131 6.1.2 High load: 2000 rpm, BMEP 8 bar 136 6.2 Results by various design concept 141 6.3 Results Using Polynomial Function as MFB 148 6.4 Application of Combustion Design to WLTP 153 6.4.1 Combustion design at steady points in WLTP operating area 153 6.4.2 Results of an application to WLTP 164 Chapter 7. Conclusions 169 Bibliography 174 국 문 초 록 193박

Smoking exposure and allergic rhinitis in children and adolescents

The prevalence of allergic rhinitis in children and adolescents is constantly increasing. However, few studies exist on the relationship between smoking and allergic rhinitis. In addition to conventional cigarettes, electronic and heated cigarettes have recently been introduced, which have several harmful effects. It is hypothesized that smoking and rhinitis are correlated; however, this relationship is complex. Previous studies reported that exposure to smoking during pregnancy is associated with allergic rhinitis development. Unlike the varied results reported in adults, studies on children and adolescents have often correlated direct/indirect smoke with allergic rhinitis, with prolonged exposure being associated with a higher risk of allergic rhinitis, particularly when exposed at an early age. Nonallergic inflammatory reactions and immunoglobulin E-mediated allergic sensitization are assumed to be the underlying mechanisms for the association between allergic rhinitis and smoking. Measures to reduce smoking are warranted to lower the incidence of allergic rhinitis in children and adolescents and to improve their health.ope

소아 알레르기비염의 위험 인자와 보호 인자

ope

Effects of Vacuuming Mattresses on Allergic Rhinitis Symptoms in Children

Purpose: To evaluate the effects of daily vacuuming of mattresses on the concentration of house dust mite (HDM) allergens and on allergic rhinitis (AR) symptoms in children sensitized to HDM. Methods: Forty children between the ages of 6 and 12 years with mild persistent AR and sensitized only to HDM were enrolled and randomly allocated to 2 groups. Caregivers of children in the experimental group cleaned the children's rooms and vacuumed their mattresses daily for 2 weeks. Caregivers of children in the control group cleaned the children's rooms without vacuuming mattresses. Symptoms of AR were checked weekly and dust samples were collected from the mattresses before and after the study. Results: Demographics at the beginning of the study were not significantly different between the 2 groups. In the experimental group, symptoms of AR and dust weight were significantly decreased after 2 weeks (total symptoms of AR, P <0.001; sneezing, P < 0.001; rhinorrhea, P <0.001; nasal obstruction, P < 0.001; itching, P <0.001; and dust weight, P = 0.006). The concentrations of HDM allergens were not changed significantly (Der p1, P = 0.333; Der f1, P = 0.841). In the control group, there were no significant changes in symptoms of AR, dust weight, or the concentration of HDM allergens. Conclusions: Our findings showed that daily vacuuming of mattresses reduced dust weight and symptoms of AR. However, the concentration of HDM allergens did not significantly decrease.ope

Clinical Characteristics of Macrolide-Refractory Mycoplasma pneumoniae Pneumonia in Korean Children: A Multicenter Retrospective Study

Mycoplasma pneumoniae is a major causative pathogen of community-acquired pneumonia in children, and the treatment of choice is macrolides. There is an increasing trend in reports of refractory clinical responses despite macrolide treatment due to the emergence of macrolide-resistant M. pneumoniae. Early discrimination of macrolide-refractory M. pneumoniae pneumonia (MrMP) from macrolide-sensitive M. pneumoniae pneumonia (MSMP) is vital; however, testing for macrolide susceptibility at the time of admission is not feasible. This study aimed to identify the characteristics of MrMP in Korean children, in comparison with those of MSMP. In this multicenter study, board-certified pediatric pulmonologists at 22 tertiary hospitals reviewed the medical records from 2010 to 2015 of 5294 children who were hospitalized with M. pneumoniae pneumonia and administered macrolides as the initial treatment. One-way analysis of variance and the Kruskal-Wallis test were used to compare differences between groups. Of 5294 patients (mean age, 5.6 years) included in this analysis, 240 (4.5%), 925 (17.5%), and 4129 (78.0%) had MrMP, macrolide-less effective M. pneumoniae pneumonia, and MSMP, respectively. Compared with the MSMP group, the MrMP group had a longer fever duration, overall (13.0 days) and after macrolide use (8.0 days). A higher proportion of MrMP patients had respiratory distress, pleural effusion, and lobar pneumonia. The mean aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and C-reactive protein levels were the highest in the MrMP group, along with higher incidences of extrapulmonary manifestations and atelectasis (during and post infection). Pre-existing conditions were present in 17.4% (n = 725/4159) of patients, with asthma being the most common (n = 334/4811, 6.9%). This study verified that MrMP patients show more severe initial radiographic findings and clinical courses than MSMP patients. MrMP should be promptly managed by agents other than macrolides.ope

공자는 무신(귀)론자인가? - 공자의 귀신론 재론 -

『논어』에는 귀신을 어떻게 섬겨야(事) 합니까?"(季路問事鬼神)라는 자로(계로)의 질문이 기록되어 있다. 일반적으로 그 질문에 대한 공자의 대답은 귀신의 존재에 관한 유교의 입장， 즉 유교의 무신론적 입장을 보여주는 것이라고 이해되고 있다. 그러나 그 질문과 대답은 귀신의 존재 여부를 둘러싸고 이루어진 것이 아님을 알 수 있다. 자로의 질문은 귀신을 어떻게 섬겨야(事) 하는지에 대한 것이다. 여기서 섬긴다는 말의 의미가 문제가 될 수 있지만, 어쨌든 그것은 귀신이 존재합니까(유무)라는 질문이 아니었다. 하지만 자로와 공자의 대화는 귀신의 존재 여부에 관한 것으로 받아들여져 왔다. 나아가 공자의 대답은 그의 합리주의， 무신(귀)론을 대변하는 대표적인 발언으로 해석되어 왔다