호기산화질소 검사의 시행과 해석

권재우 대한내과학회 2022 대한내과학회지 Vol.97 No.3

Nitric oxide is produced by the human lungs and increases in response to type 2 inflammation. The level of fractional exhaled nitric oxide (FeNO) may reflect type 2 inflammation in the airways, which is related to eosinophilic inflammation and treatment responsiveness to corticosteroids. The FeNO test is a non-invasive, simple, and safe point-of-care test to evaluate airway inflammation. It has been standardized for clinical use and has been widely utilized in daily medical practice. However, various intrinsic and extrinsic factors can affect FeNO levels, and understanding and controlling such factors will improve the utility of this measure. The FeNO test can be used to confirm an asthma diagnosis, predict treatment responses to corticosteroids, and guide inhaled corticosteroid therapy for asthma treatment.

가려움증

권재우 대한내과학회 2021 대한내과학회 춘계학술대회 Vol.2021 No.-

Emergency Department Visits for Asthma Exacerbation due to Weather Conditions and Air Pollution in Chuncheon, Korea: A Case-Crossover Analysis

권재우,한영지,오무경,이창률,김자연,김이진,김호,김우진 대한천식알레르기학회 2016 Allergy, Asthma & Immunology Research Vol.8 No.6

Purpose: This retrospective study was conducted to estimate the effects of climate factors and air pollution on asthma exacerbations using a case-crossover analysis. Methods: Patients who visited the emergency department (ED) of 2 university hospitals in Chuncheon for asthma exacerbations from January 1, 2006, to December 31, 2011, were enrolled. Daily average data for meteorological factors (temperature, daily temperature range, relative humidity, wind speed, atmospheric pressure, presence of rain, solar irradiation, and presence of fog) and the daily average levels of gaseous air pollutants (SO2, NO2, O3, CO, and PM10) were obtained. A case-crossover analysis was performed using variables about the weather and air pollution at 1-week intervals between cases and controls before and after ED visits. Results: There were 660 ED visits by 583 patients with asthma exacerbations. Low relative humidity (lag 1 and 2) and high wind speed (lag 1, 2, and 3) were associated with ED visits for asthma. Fog (lag 2) showed protective effects against asthma exacerbations in Chuncheon (risk increase: -29.4% [95% CI=-46.3% to -7.2%], P=0.013). These relationships were stronger in patients ≤19 years old than in those >60 years old. High levels of ambient CO (lag 1, 2, and 3) and NO2 (lag 2 and 3) were associated with decreased ED visits for asthma. However, there were no significant relationships among levels of ambient CO or NO2 and asthma exacerbations after adjusting for wind speed and relative humidity. Conclusions: High wind speed and low humidity were associated with an increased risk of asthma ED visits. Fog was associated with a decreased risk of asthma ED visits after controlling for seasonal variations in weather and air pollution.

An Optimized Time-synchronization Method for Simulator Interworking

권재우,김진규,우상효 한국멀티미디어학회 2019 멀티미디어학회논문지 Vol.22 No.8

In this paper, we discuss an optimization approach for time-synchronizations in networked simulators. This method is a sub-technology that is required to combine heterogeneous simulators into a single simulation. In previous time-synchronization studies, they had built a network system among networked simulators. The network system collects network packets and adds time-stamps to the networked packets based on the time that occurs in events of simulation objects in the individual simulators. Then, it sorts them in chronological order. Finally, the network system applies time-synchronization to each simulator participating in interworking sequentially. However, the previous approaches have a limitation in that other participating simulators should wait for while processing an event in a simulator in a time stamp order. In this paper, we attempt to solve the problem by optimizing time-synchronizations in networked simulation environments. In order to prove the practicality of our approach, we have conducted an experiment. Finally, we discuss the contributions of this paper.

Results of Intradermal Skin Testing with Cefazolin according to a History of Hypersensitivity to Antibiotics

권재우,김윤정,양민석,송우정,김세훈,조상헌,장윤석 대한의학회 2019 Journal of Korean medical science Vol.34 No.50

Background: The relationship between cephalosporin hypersensitivity and a history of β-lactam hypersensitivity is unclear. We evaluated the usefulness of routine intradermal cefazolin skin testing and its relationship with the history of β-lactam hypersensitivity. Methods: The electronic medical records of patients who underwent intradermal cefazolin (0.3 mg/mL) skin testing without negative controls from January 2010 to January 2011 at Seoul National University Bundang Hospital were evaluated. The history of β-lactam hypersensitivity of the patients was taken. Immediate adverse reactions after cefazolin injection were evaluated by searching the electronic medical records for key words and reviewing consultation documents of allergy specialists or dermatologists. The medical records of the patients were reviewed by an allergist. Results: There were 13,153 cases of cefazolin skin testing over the 13-month study period. Among the 12,969 cases with negative skin test results, 8 had immediate hypersensitivity related to cefazolin (0.06%). The negative predictive value of cefazolin skin testing alone wa 99.94%. The overall positivity rate of cefazolin skin tests was 1.4% (184/13,153). Of the cases with a history of allergy to β-lactams, 15% (6/40) showed a positive cefazolin skin test result compared to only 1.36% (178/13,113) of cases with no such history (P < 0.001) including som false-positive tests. Conclusion: The results suggest that routine screening involving cefazolin skin testing without negative controls is not useful for all patients, but could be helpful for those with a history of β-lactam hypersensitivity, although a large prospective study is needed to confirm this.

Mobile IP 핸드오프를 위한 효율적인 TCP 방식

권재우,박희동,조유제 한국정보과학회 2002 정보과학회논문지 : 정보통신 Vol.30 No.5

When using TCP over a mobile network, TCP responds to a handoff by invoking a congestion control algorithm, thereby resulting in a degraded end-to-end performance in a mobile network. In this paper, two schemes are proposed, TCP-MD and TCP-R. TCP-MD can detect the movement of a mobile host early on, whereas TCP-R can force the source to freeze data transmission during registration. The proposed schemes maintain end-to-end TCP semantics, making it possible to fully interoperate with the existing infrastructure. Only a small change is required in the mobile host, plus the implementation is simple because some Mobile IP messages are used to notify the handoff, eliminating the need for any additional messages. Simulations confirmed that the proposed schemes give an excellent performance under various environments. 기존 TCP가 이동 환경에 그대로 적용될 경우, 빈번하게 발생하는 핸드오프에 의한 패킷 손실에 대해 불필요한 폭주 제어 알고리즘을 수행함으로 인해 TCP의 성능 저하를 초래한다. 본 논문에서는 이동 호스트의 핸드오프 발생 사실을 최대한 빨리 감지하기 위한 TCP-MD 방식과 핸드오프 시 등록 과정동안 송신측에서 전송을 중지하여 패킷 손실을 최소화하는 TCP-R 방식을 제안한다. 제안된 방식은 종단간 TCP 연결을 유지하며 이로 인해 기존망과 호환이 가능하도록 한다. 또한, 유선 구간에서는 기존 TCP의 수정없이 사용하고, 핸드오프 발생 사실을 알리기 위해 별도의 메시지 정의 없이, 단지 이동 호스트 내 TCP에서 Mobile IP 핸드오프 시 등록 관련 메시지를 이용함으로써 TCP 성능을 향상시킬 수 있고 구현이 단순하다는 장점이 있다. 다양한 환경에 대한 시뮬레이션을 수행하여 각 제안된 방식들을 적용할 경우 TCP의 성능을 크게 향상시킬 수 있음을 보였다.

Genetic Variations in TXNRD1 as Potential Predictors of Drug-Induced Liver Injury

권재우,Eun-Soon Shin,Jong-Eun Lee,김상헌,김상훈,지영구,김윤근,박해심,민경업,Heung-Woo Park 대한천식알레르기학회 2012 Allergy, Asthma & Immunology Research Vol.4 No.3

Purpose: Drug-induced liver injury (DILI) is the most common adverse drug reaction; however, it is not easily predicted. We hypothesize that DILI has a common genetic basis. Based on the findings of previous animal studies on toxic hepatitis, we selected the thioredoxin reductase 1 gene (TXNRD1) as a candidate marker of DILI for this genetic association study. Methods: Records from 118 patients with DILI were extracted from the database of the Adverse Drug Reaction Research Group in South Korea. Causative drugs included antituberculosis drugs (n=68, 57.6%), antibiotics (n=22, 18.6%), antiepileptic drugs (n=7, 5.9%), non-steroidal anti-inflammatory drugs (n=5, 4.2%), and others (n=16, 13.7%). Seven single nucleotide polymorphisms (SNPs) in TXNRD1 (rs10735393, rs4964287, rs4595619, rs10861201, rs11111997, rs4246270, and rs4246271) were scored in 118 DILI patients and in 120 drug-matched controls without liver injury. Results: No differences were found between the frequencies of any of the 7 SNPs in the cases and controls; however, a significant association was found between a TTA haplotype composed of rs10735393, rs4964287, and rs4595619 and DILI using an allele model (odds ratio, 1.79; 95% confidence interval, 1.18-2.73; P=0.008; Bonferroni corrected P=0.024). Conclusions:These results suggest that genetic variations in TXNRD1 favor the development of DILI, although a larger confirmative study is needed.

산업단지에서의 흡착 성토재로써 제올라이트 토양혼합물의 특성평가

권재우,Rahim Shahrokhishahraki,박준범 대한토목학회 2019 대한토목학회논문집 Vol.39 No.1

A number of industrial zones in South Korea were reported contaminated by heavy metals. Such contamination could cause severe damage to the subsurface environment including soil and groundwater. The treatment of zeolite mixing with soil at the bottom of such industrial zones might prevent, or at least reduce the damage of contamination by adsorption of the heavy metals from the leakage. However, such mixtures should maintain the proper bearing capacity as a foundation fill material from the geotechnical point of viewat the same time. To investigate the effect of mixtures of zeolite with local soils for the adsorption of heavy metals (Zn, Pb) and sustainability of bearing capacity, adsorption isotherm tests and direct shear test with compaction tests were performed. Results showedthat the mixing zeolite with local soils effectively reduces the spreading of the heavy metal contamination when maintaining its proper geotechnical properties as a fill material of industrial zones. 현재 많은 국내 산업단지들은 여러 가지 중금속오염에 노출되어있다. 이러한 오염은 토양과 지하수에 심각한 오염을 초래할 수 있다. 산업단지의 하부지반을 제올라이트를 토양과 섞은 혼합물로 대체하여 이러한 오염을 방지하고자 한다. 혼합물들을 성토재를 사용하기 위해서는 최소한의 지지력을 갖춰야 한다. 제올라이트 혼합물의 중금속(아연, 납)에 대한 흡착특성과 지지력을 실험하기 위하여 등온 흡착시험, 직접 전단시험 및 표준다짐시험을 실시하였다. 실험결과, 혼합물들은 효과적으로 오염물질의 확산을 줄일 수 있고 동시에 적절한 지지력을 확보할 수 있다.

Reliability and Validity of a Korean Version of the Leicester Cough Questionnaire

권재우,문지용,김세훈,송우정,김민혜,강민규,임경환,이소희,이상민,이진영,권혁수,김경묵,김상헌,김상훈,정재원,김철우,조상헌,이병재 대한천식알레르기학회 2015 Allergy, Asthma & Immunology Research Vol.7 No.3

Purpose: There are no specific tools for measurement of the severity of chronic cough in Korea. We developed a Korean version of the Leicester Cough Questionnaire (LCQ) and tested its scaling and clinical properties. Methods: The LCQ was adapted for Korean conditions following a forward- backward translation procedure. All patients referred to chronic cough clinics at 5 university hospitals between May 2011 and October 2013 completed 2 questionnaires, the LCQ and the Short-Form 36 (SF-36), upon presentation and completed the LCQ and the Global Rating of Change (GRC) upon follow-up visits after 2 or 4 weeks. Concurrent validation, internal consistency, repeatability, and responsiveness were determined. Results: For the concurrent validation, the correlation coefficients (n=202 patients) between the LCQ and SF-36 varied between 0.42 and 0.58. The internal consistency of the LCQ (n=207) was high for each of the domains with a Cronbach’s alpha coefficient of 0.82-0.94. The repeatability of the LCQ in patients with no change in cough (n=23) was high, with intra-class correlation coefficients of 0.66-0.81. Patients who reported an improvement in cough (n=30) on follow-up visits demonstrated significant improvement in each of the domains of the LCQ. Conclusions: The Korean version of the LCQ is a valid and reliable questionnaire for measurement of the severity of cough in patients with chronic cough.

미세먼지와 기도질환

권재우 대한내과학회 2019 대한내과학회 추계학술발표논문집 Vol.2019 No.2