The levels of Indoor radon can increase in newly built apartments that mainly use construction materials such as concrete. However, radon measurement in newly built buildings has only been implemented recently, and there is a lack of sufficient data for radon management purposes. This study aimed to determine the levels of indoor radon in newly built apartments by regions, sizes of household, and floor (lower, middle, upper floor), and to explore the trend of radon reduction by time according to ventilation methods. Indoor radon was measured in 48 households in four regions (Gyeonggi-do and Gangwon-do). Measurements were performed for 48 hours and 24 hours under closed and ventilated conditions using real-time measurement devices FRD400 and RAD7, respectively. To analyze changes in radon concentration by floors, data were collected by dividing households into lower, middle, and upper floors according to their vertical height. The concentrations of indoor radon ranged from 12.1 Bq/m3 to 559.0 Bq/m3 when windows were closed and 12.0 Bq/m3~500.0 Bq/m3 when ventilated (including both mechanical and natural ventilation). On average, the concentration of closed conditions of household when sealed (arithmetic average 185.3 Bq/m3) was 1.5 times higher than the concentration during ventilation (including mechanical and natural ventilation: 123.8 Bq/m3), and around three times higher than the average for mechanical ventilation (65.7 Bq/m3). It was found that the indoor radon concentration statistically increased as the height increased and the size of the house became smaller. Typically, it took 7 to 8 hours to exceed the standard of 148 Bq/m3 after windows were closed. It decreased to less than 148 Bq/m3 within 3 to 4 hours after operating the mechanical ventilation system. However, in the case of natural ventilation, it takes more than 24 hours to reach below the standard value, and the concentrations stagnated after 24 hours. In conclusion, radon concentration in narrow spaces can be relatively high if ventilation is not sufficient due to the nature of apartments with wall-type structures. Therefore, it is necessary to prepare various radon reduction measures according to floor, size, and ventilation methods.

In the nuclear fuel cycle (NFC) facilities, the failure of Heating Ventilation and Air Conditioning (HVAC) system starts with minor component failures and can escalate to affecting the entire system, ultimately resulting in radiological consequences to workers. In the field of air-conditioning and refrigerating engineering, the fault detection and diagnosis (FDD) of HVAC systems have been studied since faults occurring in improper routine operations and poor preventive maintenance of HVAC systems result in excessive energy consumption. This paper aims to provide a systematic review of existing FDD methods for HVAC systems therefore explore its potential application in nuclear field. For this goal, typical faults and FDD methods are investigated. The commonly occurring faults of HVAC are identified through various literature including publications from International Energy Agency (IEA) and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). However, most literature does not explicitly addresses anomalies related to pressure, even though in nuclear facilities, abnormal pressure condition need to be carefully managed, particularly for maintaining radiological contamination differently within each zone. To build simulation model for FDD, the whole-building energy system modeling is needed because HVAC systems are major contributors to the whole building’s energy and thermal comfort, keeping the desired environment for occupants and other purposes. The whole-building energy modeling can be grouped into three categories: physics-based modeling (i.e., white-box models), hybrid modeling (i.e., grey-box models), and data-driven modeling (i.e., black-box models). To create a white-box FDD model, specialized tools such as EnergyPlus for modeling can be used. The EnergyPlus is open source program developed by US-DOE, and features heat balance calculation, enabling the dynamic simulation in transient state by heat balance calculation. The physics based modeling has the advantage of explaining clear cause-and-effect relationships between inputs and outputs based on heat and mass transfer equations, while creating accurate models requires time and effort. Creating a black-box FDD model requires a sufficient quantity and diverse types of operational data for machine learning. Since operation data for HVAC systems in existing nuclear cycle facilities are not fully available, so efforts to establish a monitoring system enabling the collection, storage, and management of sensor data indicating the status of HVAC systems and buildings should be prioritized. Once operational data are available, well-known machine learning methods such as linear regression, support vector machines, random forests, artificial neural networks, and recurrent neural networks (RNNs) can be used to classify and diagnose failures. The challenge with black-box models is the lack of access to failure data from operating facilities. To address this, one can consider developing black-box models using reference failure data provided by IEA or ASHRAE. Given the unavailability of operation data from the operating NFC facilities, there is a need for a short to medium-term plan for the development of a physics-based FDD model. Additionally, the development of a monitoring system to gather useful operation data is essential, which could serve both as a means to validate the physics-based model and as a potential foundation for building data-driven model in the long term.

In nuclear power plant (NPP) decommissioning, ventilation and purification of the building atmosphere are important to create a working environment, ensure worker safety, and prevent the release of gaseous radioactive materials into the environment. The heating, ventilation, and air conditioning (HVAC) system of each building is maintained, modified, or newly installed. In this study, based on APR1400, operation strategies were presented in case of ventilation abnormalities in the reactor containment building (RCB), where highly radioactive particles and high dust are most frequently generated during NPP decommissioning. For research, it was assumed that the entire RCB atmospheric ventilation during decommissioning would use the RCB purge system of the existing NPP and perform continuous ventilation. Additionally, it is assumed that areas where high radiation particles and high dust occur locally, such as reactor containers or internal segments, are sealed with tents and purified using a HEFA filter of a temporary portable HVAC, and a exhaust flow path is connected to the discharge duct of the existing RCB purge system. The possibility of abnormal occurrence was largely divided into two cases. First, when large amounts of uncontrolled pollutants are released into the atmosphere inside the RCB, discharge to the environment is stopped manually or automatically by a modified engineered safety function activation signal (ESFAS). Afterwards, the RCB purge system should be operated in recirculation mode to sufficiently purify the RCB atmosphere with a HEPA filter. Second, when the first train of the low volume purge system is not running due to a failure, standby train should be operated. If both low volume purge trains fail, a high volume purge system is used. Intermittent purge operation is preferred due to large capacity during high volume purge operation. In cases where it is not possible to operate all purge systems due to common issues such as power supply, atmospheric sampling is performed to determine whether to proceed with the work inside RCB.

South Korea has been storing UNF in spent fuel pool dry storage facility within Nuclear Power Plants. The dry storage facility of used nuclear fuel (UNF) is essential to sustain safety and sustain stable operation of a nuclear power plant. Most abroad countries have attempted to develop a variety of dry storage facility for used nuclear fuel in order to retain the safe restoration. Many studies have been conducting to safety evaluation for the dry storage facility. However, there is not a ventilation evaluation in the wake of fire event that could influence of the thermal effect on the dry storage facility, even though it will likely to occur fire events such as wildfire, air craft crash. In practice, it happened to catastrophic disaster due to the wild fire adjacent to ul-jin mountain. Also, it happened to fire accident near to the Japonia NPP in Ukraine territory caused of military air plane missile. It has not mostly been studied on the ventilation evaluation considered to thermal safety in the dry storage facility excepted for some researches. It could need the mechanical ventilation systems such as HVAC system in the dry storage system, so that thermal effect can be reduced. In this study, we conducted to the ventilation control modelling by using fire modelling tool (Fire Dynamic Simulator v.6.7). The ventilation scenarios made up for 3 case that can compare flowrate variation with ventilation control. As a result of modelling, there is no differentiation between ventilation control using performance curve with not using performance curve even though the pressure fluctuation would be increased, compared with the case of considering performance curve. Second, it evaluated that the mode for fraction control would occur to pressure rise in the state of controlling the ventilation system flowrate. However, sensitivity of flowrate control was more decreased below less than 5 seconds. Third, in the case of on/off control system revealed more higher resolution than other cases caused by flowrate variation. These results could be considered as the design guidelines for the development dry storage facility to improve the thermal performance that can reduce thermal risk. Furthermore, the study results would expect HVAC system installed in dry storage to help automatic ventilation control relevant to dry storage safety increased.

In this study, two ventilation holes were considered to prevent condensation in the circular column supporting the provision crane on a training ship(Saenuri) for Mokpo National Maritime University. The ventilation holes could be understood as the most simple and inexpensive way to prevent condensation because it was formed only by drilling. If sufficient ventilation is provided, the insulation and corrosion of an electric motor can be improved, and a comfortable state can be ensured in the circular column. The circular column had an electric motor for driving the provision crane so that the basic principle was to utilize the kinetic energy for the flow field from a cooling fan in the circular column. The ventilation holes attenuated the low-velocity area in the circular column and contributed to internal flow circulation with updrafts. The results were discussed through numerical analysis based on computational fluid dynamics.

수소는 산소와 반응하여 전기에너지를 만들고 부산물로 물을 생성하므로 친환경 선박의 대체 연료로 대두되고 있다. 그러나 수소는 일반 화석연료와는 달리 낮은 점화 에너지와 높은 가연성 범위로 인하여 폭발의 위험성이 높은 물질이다. 그래서 선박에서 사용 되는 수소의 안전성을 확보하기 위해서 수소의 누출․확산에 관한 유동 특성을 연구하는 것은 매우 중요하다. 본 연구에서는 선박 내부 와 같은 밀폐공간에서 수소가 누출되었을 때 누출량, 통풍량, 환기 방식 등이 환기 성능에 어떤 영향을 미치는지에 대하여 수치적 해석을 수행하였다. 수치해석에는 CFD 상용 소프트웨어인 ANSYS CFX ver 18.1을 이용하였다. 누출량은 1  = 1 g/s로 하여 1 , 2 , 3 로 변경하 였고, 통풍량은 1 Q = 0.91 m/s로 하여 1 Q, 2 Q, 3 Q로 변경하였으며 환기 방식은 typeⅠ, typeⅡ, typeⅢ로 변경하면서 환기 성능을 분석하였 다. 누출량이 1 에서 3 로 증가할수록 저장실 내의 수소 몰분율(HMF)는 약 2.4 ~ 3.0배 높게 나타났으며 통풍량 증가는 누출량에 대비하 여 약 62.0 ~ 64.8 % 정도 환기 성능이 개선에 효과가 있었다. 그리고 폭발의 위험성을 낮추기 위한 통풍량은 최소 2 Q 이상 되어야 하며, 수 소탱크 저장실 내부의 부압 형성을 위해서는 type Ⅲ가 가장 적합한 방식이라고 판단하였다.

본 연구는 권취식 측창을 갖는 아치형 단동 플라스틱 온실 내 강제환기장치 설치 및 운용, 환기 성능 개선방안 등을 제안 하기 위해 온실 내부에 유동팬과 배기팬을 설치하여 강제환기 장치 사용에 따른 온실 내부기온 강하 특성을 정량적으로 조 사하였다. 시험은 3가지 환기 조건(측창, 측창+순환팬, 측창+ 순환팬+배기팬)에서 수행되었다. 각 조건 데이터로거를 이용 하여 환기 시작과 동시에 온실 내외부 기온 및 외부환경 변화 를 측정·기록하였고, 환기 방식별 기온차 변화의 평균값으로 부터 정규기온차를 계산하여 기온 강하 효과를 비교하였다. 오전(11:00－12:00)에는 환기 방식에 상관없이 환기 초반 정 규기온차가 일시적으로 증가했다가 감소하는 것으로 나타났 다. 강제환기장치가 더 많이 사용될수록 최대 정규기온차는 1.158에서 1.037로 감소하였고 최대 정규기온차에 도달하는 시간도 340초에서 110초로 단축되었다. 강제환기장치의 사 용은 정규기온차가 0.8까지 감소하는데 소요된 시간을 1,030 초에서 550초로, 0.6까지는 1,610초에서 915초로, 0.4까지는 2,315초에서 1,360초로, 자연환기의 약 60% 수준으로 감소 시켰다. 오후(14:00－15:00)에는 정규기온차의 증가가 관측되지 않았지만, 환기 시작과 동시에 기온차가 감소하기 시작 했다. 또한 강제환기장치가 더 많이 사용될수록 정규기온차 가 0.8까지 내려가는 시간을 560초에서 345초로, 0.6까지는 825초에서 540초로, 0.4까지는 560초에서 345초로, 약 70% 수준으로 감소시켰다. 따라서, 보다 효과적이고 경제적인 환 기를 위해 강제환기장치는 오전과 같이 열부하가 높은 환경에 서 적극적으로 사용하는 것이 바람직하다고 판단된다.

수소는 지구 온난화의 주범인 온실가스(GHG) 배출을 감소시키고 선박용 친환경 연료로서 대두되고 있다. 수소는 가연 하한계 (Lower Flammability Limit, LFL)가 4 ~ 75 %이고 폭발 위험성이 큰 물질이다. 그래서 선박용으로 사용되려면 누출에 대비한 안전성이 충분히 확보되어야 한다. 본 연구에서는 수소탱크 저장실에서 수소 누출이 발생한 경우, 급․배기구의 면적 변화가 환기 성능에 미치는 영향을 분석하였다. 급․배기구의 면적은 1A = 740 mm × 740 mm이며 저장실 표면에 크기 및 위치 변경이 쉽도록 설정하였다. CFD 상용 소프트웨 어인 ANSYS CFX ver 18.1을 이용하여 급․배기구의 면적을 1A, 2A, 3A, 5A로 변경하였고, 면적 변화에 따른 저장실 내의 수소 몰분율을 분석하였다. 그 결과 급기구 면적이 배기구 면적 증가에 비해 누출 수소의 농도를 더 감소시켰으며 단일 급기구보다 최소 2A 이상에서 환기 성능이 향상되었다. 급기구의 면적이 증가할수록 수소 층화가 저장실 상부부터 균일하게 형성되었지만 LFL 범위는 벗어나 있었다. 그러나 배기구는 면적을 단순히 증가하는 것만으로는 환기 성능에 미치는 영향은 미비하였다.

This study was carried out to investigate the effect of side vent heights on temperature and relative humidity inside and outside the single-span plastic greenhouse (W: 7 m, L: 40 m H: 3.9 m) during natural ventilation. Four different heights (120, 100, 80, 60 cm) of the side vent were used as an experimental condition. Variations of temperature and relative humidity inside and outside the greenhouse and the differences between heights were compared by using one-way ANOVA. In the daytime, the difference in temperature between inside and outside the greenhouse was dropped from 14.0°C to 7.1°C as the side vent height increased. The temperature difference in the nighttime was less than 0.2°C regardless of the height. One-way ANOVA on the temperature difference between heights presented that the statistical significance was founded between all of the combinations of height in the daytime. The difference in relative humidity between inside and outside the greenhouse was grown from –13.8% to – 22.2% with a decrease in the side vent height. The humidity difference in the nighttime was less than 1% regardless of the height. One-way ANOVA on the humidity difference revealed that most of the side vent heights showed significance in the daytime but between 100 and 80 cm was not significant. It seemed because the external air became cooler during the experiment with a height of 80 cm. Conclusively, this study empirically demonstrated that the higher side vents resulted in the decrease of differences in temperature and relative humidity between inside and outside the greenhouse, and also the effect of side vent height was statistically significant. This study may be helpful for deciding the height of the side vent effective for controlling temperature and relative humidity in a single-span greenhouse during natural ventilation.

In this study, we learned about the effects of indoor radon concentration reduction associated with the operation of a mechanical ventilation system at an apartment house. The experimental parameters were mainly the indoor radon level and air change rate, which were controlled by the amount of emissions released and fan motor speed. Even at the high level of radon diffused in an apartment house, indoor radon concentrations converged to the Korean national guideline level within 3 to 4 hours when the air was ventilated at 0.5 ACH and 0.7 ACH. In the case of 0.3 ACH, however, where the degree of ventilation was insufficient compared to the legal air change rate, the high concentration indoor radon could not be sufficiently removed even if the mechanical ventilation system was operated for more than 14 hours continuously. When the indoor radon level was high, the reduction rate was 34.3% for 0.3 ACH, 70.4% for 0.5 ACH, and 69.7% for 0.7 ACH at 6 hours-operation, while at the medium-level, indoor radon can be reduced by 46.2% (0.3 ACH) to 73.2% (0.7 ACH). Depending on the indoor concentration range, it may be required to secure a ventilation rate of 0.5 ACH or more at all times. In addition, in apartment houses with excellent airtight performance, even if indoor radon is at a level similar to the national guideline, it is difficult to expect a reduction in the concentration due to natural decay. Therefore, it is desirable to lower the indoor concentrations as much as possible.

연구는 참외 재배 지에서 흰가루병, 담배가루이 및 두점박이응애가 동시에 발생하였을 때 45, 40, 35°C (대조구)의 온도에서 측창으로 환기 처리 시, 온실 내 온 ․ 습도의 변화, 병충해 발생과 잎말림, 그리고 개화조절에 미 치는 효과를 검토하였다. 3월 3일 ‘히든파워’ 대목에 접붙여진 ‘알찬꿀’ 참외를 40cm 간격으로 격리상에 심었고, 위 에 언급한 병해충이 모든 처리구에서 발생한 6월 18일부터 7월 13일까지 처리하였다. 온실의 온도는 맑은 날에는 설정 온도 지점까지 증가되었고, 45°C 환기 처리에서 고온 고습이 약 9시간 동안 유지되었다. 주간 최고 기온과 최 저 상대습도 차이는 45°C 환기 처리에서 가장 높았다. 환기 처리 11일 후에는 흰가루병과 두점박이응애 피해가 45°C 환기 처리에서 거의 회복되었지만 40°C와 35°C에서는 그렇지 않았다. 처리 14일 후, 담배가루이와 두점박이 응애 밀도는 45°C에서 유의하게 감소하였으나 흰가루병 증상은 유의하게 감소하지는 않았다. 잎말림은 고온에서 유발되었으나 45°C에서도 심하지 않았다. 처리 26일 후, 새로 나온 줄기의 15 마디의 개화수를 조사한 결과, 45°C에 서 암꽃이 전혀 나오지 않았고 수꽃은 1.2개로 나타났다. 이상의 결과는, 고온기에 45°C의 고온에서 2－3주간 환기 처리는 온실 내부의 고온 고습을 유도하여 흰가루병, 담배가루이, 두점박이응애를 통제하고, 개화를 억제하여 참외 의 영양 생장을 회복할 수 있는 방법으로 사료되었다.

This study was designed to verify what effect the use of a natural ventilation system can have on improving indoor air quality with regard to radon in various concentration ranges in an apartment house. The results show that both high (2~3 times higher than 148 m3) and low (similar to 148 Bq/m3) levels of indoor radon concentrations can be reduced close to and/or below the Korean IAQ guideline within 6 hours when the natural ventilation system is operated at approximately an air change rate of 0.5. In the case of an air change rate of 0.3, however, the indoor radon levels cannot meet the national guidelines and the reduction effect was insufficient with regard to various radon concentrations. Typically, the air change rate of a natural ventilation system is affected by meteorological factors such as temperature, relative humidity, wind speed, pressure. Its effectiveness varies according to such factors, for that reason, the reduction effects on radon did not increase proportionally with the ventilation time in this study.

요즘은 건강을 위한 스마트 헬스 케어 웨어러블의 개발이 가속화되는 시대이다. 그 중 활발한 연구 분야 중 하나인 EMS 전기자극을 활용한 웨어러블 제품이 많이 출시되었다. 하지만 연구되거나 출시되어있는 EMS 웨어러블은 근육의 세분화에 집중하지 못한 포괄적인 전신 슈트나 복부 전체를 덮는 벨트 형식으로 출시되어있다. 이에 본 연구에서는 특정 근육을 세분화시킨 EMS 패턴을 적용하고 복압 벨트에 호흡을 측정할 수 있는 스트레치 센서를 부착하여 두 가지 호흡법을 활용해 연구를 진행하고자 한다. 측정방법은 들숨과 날숨으로 실험을 진행하며 대상자는 건강한 신체의 20대 남성 10명을 대상으로 진행했다. 본 연구의 결과 흉식호흡과 복식호흡 모두 센서의 민감도는 5mm, 3mm, 기본 센서 순으로 센서별 순위 결과를 확인할 수 있었고 EMS 복압 벨트를 통해 전기자극을 적용 전, 후로 나누었을 때전기자극을 적용한 후 호흡의 활성화가 향상되었음을 알 수 있었다. 연구의 결론은 2가지 호흡법을 신체 기능적 근거로 제작한 2가지 패턴으로 인해 호흡법에 적합한 전기자극을 적용 시 적용하지 않았을 때 보다 3가지 센서로 호흡 활성화 효과와 센서 간 민감도 차이를 확인할 수 있었다. 본 연구 결과를 기반으로 후속 연구에서는 EMS 패턴과 스트레치 센서가 통합된 의복형 웨어러블 제품에 실시간 모니터링이 가능한 호흡 스마트 의류를 개발하고자 한다.

본 연구는 부산광역시를 대상으로 열환경을 개선하기 위한 바람길 관리 방안 제안을 목적으로 한다. 이를 위해, Landsat-7 위성 열영상 자료와 공간통계 분석을 실시하여 부산광역시의 Hot spot과 Cool spot 지역 특성을 파악하였으며, WRF 기상모의를 통해 주요 바람길을 분석하였다. 그 결과, Hot spot 지역 중 열환경 개선이 요구되는 지역은 부산진구, 동래구, 연제구와 사상구 공업지역, 대규모 시설지역에는 부산항 부두로 나타났으며 주요 바람길에는 금정산~백양산~ 구덕산 계곡부로서 확인되었다. 이를 바탕으로 바람길 관리 전략을 제시하면 다음과 같다. 공업시설과 부산항 일대는 대기 온도 상승 요인으로서 주변 지역의 열환경을 악화시키므로 시설의 온도저감 및 바람길을 고려한 도시·건축계획이 요구된다. 바람길 관리가 필요한 지역으로 만덕동, 사직동 일대 산림에 대한 추가적인 훼손이 일어나지 않도록 하여야 하며, 산림과 인접한 지역의 대규모 고층아파트는 산림에서 생성된 차고 신선한 공기의 흐름을 방해하므로 금정산과 접해있는 제3종 일반주거지역의 신규·재개발에 따른 고층아파트 단지 조성은 지양해야 한다. 본 연구 결과는 부산광역시의 기후변화에 대응한 도시계획 및 환경계획수립 시 기초자료로 활용할 수 있을 것으로 기대한다.

Numerical analysis for flow and noise characteristics of sirocco fan design factors is conducted in this study. 4 cases of blade angle(α=24°~30°) and 5 cases of RPM(390~1170RPM) are calculated. Flow characteristics are compared for the number of blades. Outlet flow rate is tended to decrease as the number of blades increased. There is little difference in the flow characteristics for the angle of blade. The highest outlet flow rate is predicted at α=24°, and the lowest at α=28°. Flow and noise characteristics are compared for α=24° and 26°. Outlet flow rate is almost similar in both cases, but noise for α=24° is predicted higher at high RPM conditions.