• 한국환경보건학회지
• /
• 제46권6호
• /
• pp.627-635
• /
• 2020

Objectives: Indoor air quality has become more important aspeople spend most of their times indoors. Since students spend most of their times at home or at school, they are more likely to be exposed to indoor air pollutants. Ventilation in school classrooms can affect health and learning performance. In this study, ventilation deficiency was evaluated in school classrooms using Monte Carlo simulation. Methods: This study used sensor-based monitoring for six months to measure carbon dioxide (CO2) concentrations in classrooms in elementary, middle, and high schools. The volume of the classroom and the number of students were investigated, and the students' body surface area was used to calculate the CO2 emission rate. The distribution of ventilation rates was estimated by measured CO2 concentration and a mass-balance model using Monte Carlo simulation. Results: In the elementary, middle, and high schools, the average CO2 concentrations exceeded 1000 ppm, indicating that the ventilation rates were insufficient. The ventilation rates were deficient from July to August and in December, but showed relatively high ventilation rates in October. Forty-three percent of elementary schools, 56% of middle schools, and 62% of high schools showed insufficient ventilation rates. Conclusions: The ventilation rates calculated in elementary, middle and high schools were found to be quite insufficient. Therefore, proper management is needed to overcome the lack of ventilation and improve air quality.

• 한국기계연구소 소보
• /
• 통권19호
• /
• pp.31-42
• /
• 1989

To investigate design factors of dilution ventilation system, numerical analysis of air contamination flow and concentration distribution have been made, by using the low Reynolds number turbulent model. And flow visualization and measurement of particle concentration for that model also have been made. By comparing of these results we have secured the essential data for the adequate counterplan of dilution ventilation system. The results of this study are as follows: 1) Inlet should be located near the wall for the prevention of the formation of the recircula¬tion zone. 2) In case of natural exhaust, air contamination flow is driven to the far outlet from the inlet. 3) It is favorable for dilution to make turbuence as much as possible.

• Safety and Health at Work
• /
• 제11권4호
• /
• pp.517-525
• /
• 2020

Background: The study was planned to show the status of indoor microorganisms and the status of the reduction device in the military dog clinic. Methods: Airborne microbes were analyzed according to the number of daily patient canines. For identification of bacteria, sampled bacteria was identified using VITEK^®2 and molecular method. The status of indoor microorganisms according to the operation of the ventilation system was analyzed. Results: Airborne bacteria and fungi concentrations were 1000.6 ± 800.7 CFU/m³ and 324.7 ± 245.8 CFU/m³. In the analysis using automated identification system, based on fluorescence biochemical test, VITEK^®2, mainly human pathogenic bacteria were identified. The three most frequently isolated genera were Kocuria (26.6%), Staphylococcus (24.48%), and Granulicatella (12.7%). The results analyzed by molecular method were detected in the order of Kocuria (22.6%), followed by Macrococcus (18.1%), Glutamicibacter (11.1%), and so on. When the ventilation system was operated appropriately, the airborne bacteria and fungi level were significantly decreased. Conclusion: Airborne bacteria in the clinic tend to increase with the number of canines. Human pathogenic bacteria were mainly detected in VITEK^®2, and relatively various bacteria were detected in molecular analysis. A decrease in the level of bacteria and fungi was observed with proper operation of the ventilation system.

• 생물환경조절학회지
• /
• 제13권3호
• /
• pp.149-155
• /
• 2004

본 연구에서는 주행경로의 설정 및 제어가 용이한 고정 경로 방식을 이용한 주행 시스템을 개발하여 온실의 형태, 고랑의 위치 등에 무관하게 자동관수 및 송풍장치에 따른 생육상태를 실험할 수 있는 다목적 자동작업시스템을 개발하였다. 이 시스템의 성능들을 알아보기 써해 초화류에 대하여 실험한 결과 다음과 같은 결과론 얻었다. 인력두상관수 처리구에서는 전반적으로 생육의 부진을 나타냈으며, 자동관수 처리 중 송풍을 하지 않은 무풍처리구치 경우, 초장 및 엽면적이 높은 것으로 나타났다. 초장의 억제는 저속과 고속송풍처리구에 있어 초장억제 효과가 유의성이 있게 나타났으며, 풍속이 빠를수록 초장억제효과가 높게 나타났다. 줄기의 지름은 송풍을 하지 않고, 자동관수 3회를 한 경우 줄기의 지름이 작은 것으로 나타났다. 엽수는 인력관수나 자동관수 2회 처리에 비하여 3회 처리가 더 많은 것으로 나타났다. 생육은 관수회수가 많을수록 생장량이 높게 나타났다.

• 한국전자통신학회논문지
• /
• 제16권3호
• /
• pp.551-558
• /
• 2021

IoT와 센서를 기반으로 원격으로 제어할 수 있는 액추에이터 모듈의 지능형 환기 기능을 구현하기 위해, 실내 가스/CO2/습도 온도 및 실내/외 미세먼지 관련 실외 환경을 감지하는 사전 설정된 개수의 데이터를 기반으로 환기 포트를 개폐하기 위한 알고리즘 설계 및 구동 회로를 구성하여 환기창시스템을 구현하였다. 실내공기 순환모듈의 전송데이터관련 센서와 조건이 많아 데이터 저장·관리·분석에 어려움을 겪고 있다. 빅데이터 기술은 실내 공기 순환 시스템에 채택되어야 한다. 원격 모니터링과 원격 무선 제어 화면은 환기구시스템의 상태를 추출하여 관리함으로써 분리 및 작동 조건을 자동화할 수 있도록 구축되었다. 엑츄에이터 및 센서로 구성된 환기창시스템의 제어 및 센싱용 대량의 데이터전송 안정성을 확보하기 위해 MQTT를 적용하고 시스템 오류를 대비하여 운용의 빅데이터 안정적인 전송 보장을 위해 RocketMQ를 활용하여 시스템을 구성하였다.

• KIEAE Journal
• /
• 제7권6호
• /
• pp.3-8
• /
• 2007

Recently, because of the continuous rise of international oil price, energy saving is strongly demanding. So, Ecological technics of architecture such as use of natural energy have been actively explored in the field of building. In the method of utilizing natural energy, the key point is to saving energy effectively as not lowering the comfort of indoor environment, various systems investigated. Many papers about double skin facade system have been reported, it is announced broadly that the system is very effective in improvement of natural ventilation and indoor thermal environment, and also protecting outdoor sound. The shaft box facade is a special form of box window construction. It consists of a system of box windows with continuous vertical shafts that extend over a number of stories to create a stack effect. The facade layout consists of an alternation of box windows and vertical shaft segments. This research investigated the natural ventilation performance of shaft box type balcony which conform the shaft box type double skin to the exiting balcony construction. First, analyzed various types of exiting apartments, proto-type was decided. By using virtual environment Program, modeling the proto-type, compared the contribution of air temperature and the effect of outdoor air cooling. by this research, we confirmed that shaft box type balcony had many possibility for improvement of indoor environment.

• 대한통합의학회지
• /
• 제11권3호
• /
• pp.1-10
• /
• 2023

Purpose : This study was conducted to determine the effect of intervention using a smartphone application on abdominal muscle thickness and maximum voluntary ventilation when conducting pelvic floor muscle exercise (PFME). Methods : This study was performed on 14 subjects. They were divided into two groups; PFME using smartphone application (n=7), common PFME (n=7). Both of group executed the exercise 5 times a week for 1 weeks. Abdominal muscle thickness was measured using ultrasound. Maximum voluntary ventilation was measured using a spirometer. The smartphone application used the paid version of Kegel trainer. This material was analyzed by the paired t-test to compare differences on each group and the independent t-test to compare between the two groups. Results : The PFME group using the smartphone application showed a significant increase in the transverse abdominis and internal oblique muscles (p<.05). The common PFME group showed a significant increase in the internal oblique muscle (p<.05). There was no significant difference in variation of the muscle thickness between the two groups (p>.05). The PFME group using the smartphone application showed a significant increase in the maximal voluntary ventilation (p<.05). There was no significant difference in variation of the maximal voluntary ventilation between the two groups (p>.05). Conclusion : As a results of this study, PFME using a smartphone application seems to induce voluntary participation of subjects and maintain continuity against time constraints. As a result, it is thought that using a smartphone application when performing PFME is efficient and convenient in terms of research method. However, this study is difficult to generalize due to the small number of subjects and short intervention period. Therefore, additional research should be conducted by modifying and supplementing these limitations.

• Journal of Microbiology and Biotechnology
• /
• 제17권10호
• /
• pp.1622-1628
• /
• 2007

We characterized the efficacy of an electrostatic precipitator (ESP) air-cleaner in reducing the concentration of Serratia marcescens in an enclosed space. We used an experimental room ($4.5{\times}3{\times}2.9\;m$) in which electrostatic air-cleaners were located. Two air-cleaners enhanced the equivalent ventilation rates in the chamber by about 3.3 air changes per hour (ACH) over the 2 ACH provided by the mechanical ventilation system. Natural die-off of the organisms provided an additional equivalent of 3 ACH, so that the total ventilation rate with the ESP air-ccleaners was 8.3 ACH. We also examined whether the ESP air-cleaners altered the deposition of Serratia marcescens aerosols on the experimental room surfaces. We did not find any significant differences in the number of colony forming units recovered from surfaces with and without the air-cleaners. We installed UV lights inside the ESPs and determined if UV light, in addition to electrical fields, increased the efficacy of the ESPs. The presence of UV light inside the ESP reduced S. marcescens aerosols by approximately 2 ACH. Finally, a box model indicates that the efficiency of the air-cleaner increases for both biological and nonbiological particles at ventilation rates of 0.2-1, which are typical for residential settings.

• 한국응급구조학회지
• /
• 제19권2호
• /
• pp.7-17
• /
• 2015

Purpose: This study aimed to compare the effects of rescue ventilation maneuvers on the quality of two-rescuer cardiopulmonary resuscitation (CPR). Methods: We implemented mouth to mouth (MMV), mouth to pocket mask (MPV) and bag-valve mask ventilation (BMV) maneuvers. Each team of two-nurses was randomized to perform three consecutive sessions of two-rescuer CPR by using three artificial ventilation maneuvers. Results: The subjects were 26 teams of nurses (female: 96.2%, male: 3.8%, age: 26.6 years). Failed ventilation was more frequent in BMV ($2.23{\pm}2.21$, p <.001) than MMV ($0.31{\pm}0.74$) and MPV ($0.38{\pm}0.64$). BMV had more compressions per minute ($93.7{\pm}5.7$) than MMV ($87.0{\pm}7.2$, p = .001) and shorter total compression pause time ($46.1{\pm}5.8sec$) and compression pause fraction ($23.3{\pm}2.2%$) than MMV ($54.8{\pm}10.3sec$, p = .001, $25.5{\pm}3.5%$, p = .001, respectively) and MPV ($53.1{\pm}7.1sec$, p =. 006 and $25.8{\pm}2.6%$, p = .006, respectively). Conclusion: In our simulation study, BMV reduced the compression pause time and increased the number of compressions per minute, thus indicating CPR provided to patients was effective. However, considering the high rate of ventilation failure, we recommend periodic training.

• 국제초고층학회논문집
• /
• 제10권1호
• /
• pp.73-83
• /
• 2021

The door open time, resulting from occupants evacuating from apartments, is an important parameter when assessing the performance of smoke ventilation systems in high-rise apartment buildings. However, the values recommended in UK design guidance appear to have limited substantiation. Monte Carlo simulations have been carried out considering variabilities in door swing time, flow rate and number of occupants. It has been found that the door open time can be represented by a lognormal distribution with a mean of 6.6, 8.7 and 11.1 s and a standard deviation of 1.7, 3.2 and 4.7 s for one, two and three-bedroom apartments, respectively. For deterministic analyses, it is proposed that the 95th percentile values may be adopted in line with recommended practice for other fire safety design parameters such as fuel load density and soot yield, giving door open times of 10 s to 19 s, depending on the number of bedrooms.