PURPOSES : Carbon dioxide (CO2) is a cheaper and easier to installer fire suppressant than other extinguishing gases and is easy to install, but extinguishes fires by is suffocation. As a result, suffocation accidents continue to occur in facilities equipped with CO2 fire-extinguishing facilities, Emission standards have yet to be established. This study aims to address the issue. METHODS : To effectively remove CO2 emitted from installed systems, we reviewed and analyzed previous related research and existing international standards. RESULTS : In protected areas where CO2 fire-extinguishing systems are installed, emission facilities should discharge the emitted CO2 before it enters the protected spaces. CO2 sensors can determine whether safe entry is possible or whether respirators are required. CONCLUSIONS : This study presented a specific installation method for emission facilities capable of actively discharging CO2. Applying this method is expected to contribute to improving safety in facilities equipped with CO2 fire-extinguishing facilities.

As awareness about the danger of radon in indoor air has increased, various studies have been conducted to reduce the source of radon. This study was performed to investigate the effect of radon mitigation technology in a railway tunnel. Radon barrier paint and radon shield membrane developed to reduce the concentration of radon in soil and construction material were applied in the tunnel. The tunnel was divided into three sections, A, B, and C, and radon barrier paint, a buffer section, and radon shield membrane were applied, respectively. After securing a sealing screen to the floor and division of each section, radon concentrations were measured and compared before and after each product was applied, and statistical significance was confirmed through the Wilcoxon signed rank test. Measurement was performed with the In-Situ Method and Closed Chamber Method. Radon concentration measured by the in-situ method changed in A section to 124.1 Bq/m2/day from 614.1 Bq/m2/day (79.8%, z=-2.521, p<0.05), in B section to 416.2 Bq/m2/day from 467.1 Bq/m2/day (10.9%, z=-0.980, p=0.327), and in C section to 47.3 Bq/m2/day from 645.6 Bq/m2/day (92.7%, z=-2.521, p<0.05). Radon concentration measured by the closed chamber method recorded a decrease in A section to 88.8 Bq/m3 from 364.2 Bq/m3 (75.6%, z=-2.201, p<0.05), in B section to 471.8 Bq/m3 from 583.3 Bq/m3 (19.1%, z=-0.700, p=0.484), and in C section to 115.9 Bq/m3 from 718.8 Bq/m3 (83.9%, z=-2.521, p<0.05). In addition to soil, it is very important to mitigate radon from building materials with a high contribution rate of radon in order to manage radon by source. Due to the spatial characteristics of railway tunnels, soil and wall concrete structures are exposed as they are, so it is considered that radon mitigation actions are required utilizing verified methods with high mitigation efficiency.

The anaerobic digestion process produces methane while stabilizing sludge. As of 2020, 62 anaerobic digesters in public wastewater treatment plants are operational in Korea. Many researchers have studied to improve digester performance. Thermal hydrolysis technology is one of the pre-treatment methods for treating sludge. Reduced retention time and enhanced biogas production are the main advantages of sludge disintegration at relatively high temperatures and pressures. But nutrients like nitrogen and phosphorus are released from the pre-treated sludge. Phosphorus is a non-renewable resource that is essential to food production. Wastewater receives 20% of the total phosphate discharge, while 90% of the influent phosphorus load is in sludge. For efficient phosphorus recovery, it is essential to comprehend the phosphorus release characteristics during wastewater treatment, including anaerobic digestion. Biological or chemical processes can achieve phosphorus removal to comply with the effluent discharge limits regulations. The three primary sources of phosphorus in sludge are aluminum-bound phosphorus (Al-P), polyphosphate in phosphorus-accumulating organisms (PAOs), and iron-bound phosphorus (Fe-P). Anaerobic digestion is the typical method for recovering carbon and phosphorus. However, previous research has demonstrated that most phosphorus in anaerobic digestion occurs as a solid phase coupled with heavy metals. Therefore, the poor mass transfer rate results in a slow phosphorus release. Due to the recent growth in interest and significance of phosphorus recovery, many researchers have studied to improve the quantity of phosphorus released into the liquid phase through chelation addition, process operation optimization, and disintegration using sludge pre-treatment. The study aims to investigate characteristics of the phosphorus release associated with the thermal hydrolysis breakdown of sludge and propose a method for recovering phosphorus in a wastewater treatment plant. When solubilizing sludge using thermal hydrolysis pre-treatment, organic phosphates, inorganic phosphates, and polyphosphates are converted into ortho-phosphate. Therefore, applying thermal hydrolysis, anaerobic digestion, and phosphorus recovery processes (struvite formation or microbial electrolysis cells) can recover carbon and phosphorus.

Coffee is the most popular beverage in the world and various pollutants, including volatile organic compounds (VOCs), are emitted from the coffee manufacturing workplace (roasting process). In this study, we analyzed the characteristics of VOCs emissions from roasted Arabica coffee bean powder using a VOCs emission chamber with a PTR-ToF-MS. The emission test was maintained under constant temperature (20 ± 2oC) and humidity (50 ± 5%) conditions. As a result of the emission test, most of the target compounds had a high concentration in the initial period, and decreased emissions as time lapsed. Acetaldehyde showed the highest concentration and was initially 78 ppm during the test period. Acetaldehyde was followed by propionic acid at 61 ppm, propanal at 51 ppm, and isobutanal at 50 ppm. As a result of comparing the occupational exposure limits (OELs) of individual VOC emitted during the coffee roasting process, the OELs of four substances, including acetaldehyde, propionic acid, acetic acid, and pyridine were identified. Of all four substances, only pyridine exceeded the OELs, and the other compounds had levels of 10% to 30% of the OELs.

밸브의 내부 누설 현상은 밸브의 내부 부품의 손상에 의해 발생하며 배관 시스템의 사고와 운전정지를 일으키는 주요 요인이 다. 본 연구는 버터플라이형 밸브의 내부 누설에 따라 배관계에서 발생하는 음향방출 신호를 이용하여 배관 가동 중 실시간 누설 진단의 가능성을 검토하였다. 이를 위해 밸브의 작동 모드별로 측정한 시간영역의 AE 원시신호를 취득하였으며 이로부터 구축한 데이터셋은 데 이터 기반의 인공지능 알고리즘에 적용하여 밸브의 내부 누설 유무를 진단하는 모델을 생성하였다. 누설 유무진단을 분류의 문제로 정의 하여 SVM 기반의 머신러닝과 CNN 기반의 딥러닝 분류 알고리즘을 적용하였다. 데이터의 특징 추출에 기반한 SVM 분류 모델의 경우, 이 진분류 모델에서 구축된 모델에 따라 83~90%의 정확도를 나타냈으며, 다중 클래스인 경우 분류 정확도가 66%로 감소하였다. 반면, CNN 기반의 다중 클래스 분류 모델의 경우 99.85%의 분류 정확도를 얻을 수 있었다. 결론적으로 밸브 내부 누설 진단을 위한 SVM 분류모델은 다중 클래스의 정확도 향상을 위해 적절한 특징 추출이 필요하며, CNN 기반의 분류모델은 프로세서의 성능 저하만 없다면 누설진단과 밸브 개도 분류에 효율적인 접근방법임을 확인하였다.

Asphalt concrete(Ascon) is used to repair potholes and cracks. Special truck-mounted cargo boxes transport 200℃ asphalt concrete to repair potholes and cracks. However, long working and transportation hours to repair wide roads decrease the temperature of the asphalt concrete inside the cargo boxes. If the asphalt concrete temperature drops below 170℃, the adhesion with roads that need repair decreases. Therefore, the temperature of the asphalt concrete needs to be maintained for a long time. Conventional asphalt concrete cargo boxes are mostly burner-type models using hot air to prevent the temperature of the asphalt concrete from dropping. However, there are significant temperature differences between the asphalt concrete near and far away from the hot air, so the temperature decreases over time and leads to the disposal of large amounts of asphalt concrete. This causes waste of resources and environmental pollution. Therefore, this study proposed a heat dissipation cut-off type cargo box model to solve this problem and demonstrated its performance over conventional burner-type models through tests and analysis.

Recently, there has been growing interest in harmful substances released from household items such as volatile organic compounds (VOCs) and this has increased people’s environmental awareness. In this study, adhesives and manicures were used as samples of indoor household goods and formaldehyde emission and tested over time under temperature conditions of 15oC, 25oC, 35oC, and 45oC. The small chamber method as the indoor air quality process test method was employed and used to evaluate the concentration of formaldehyde emissions. As a result, formaldehyde emissions gradually decreased over time in both tests using adhesives and manicures. The cumulative emission showed a logarithmic function over time, and the formaldehyde can be released for longer periods of time at lower temperature conditions. The logarithmic value and response time showed linear relationships, and it can be inferred that the formaldehyde was released from the sample through the first order reaction. Furthermore, the relationship between temperature and velocity constants which was determined using the Arenius linear equation showed that the reaction rate of formaldehyde can be estimated by a temperature change.

The security accidents occurring in ships and at seas and ports became very serious, and in particular, the maritime terrorism and abduction by pirates have emerged at the international level as a problem. The international maritime organization (IMO), accordingly, entered into such forces as the SOLAS chapter and measures in order to reinforce the maritime security and the security for ships and port facilities in 2004. In this study, the JDS-S4 improved as an oriented speaker to reinforce the ship security by enabling the clear communication even at long distance was tested by using the conducted emission test(CE101) and a standard test of the US military standard (MIL-STD-461F). Also, the result of this study was shown to satisfy the standard.

각기 다른 화합물들을 성유인제로 이용하는 3종 과수해충인 복숭아순나방(Grapholita molesta), 복숭아심식나방(Carposina sasakii), 복숭아명나방(Conogethes punctiferalis)을 대상으로 단일 성페로몬 미끼 방출제에 2종 혹은 3종의 성페로몬 미끼를 섞어 복숭아원과 사과원에서 유인력을 검정하였다. 복숭아원에서 실시된 복숭아순나방 유인에서 복숭아심식나방이 섞인 혼합미끼 트랩에서 유인력이 감소하였으나, 혼합미끼를 이용한 복숭아원에서의 성충밀도 변이는 단일미끼 트랩과 높은 상관성 보였다. 사과원에서는 복숭아순나방에 대한 혼합미끼의 유인력 감소는 관찰되지 않았다. 복숭아심식나방 유인은 복숭아원과 사과원 모두에서 혼합미끼의 유인력은 단독미끼의 유인력과 유의한 차이가 없었고, 복숭아원에서 단독미끼와 혼합미끼 사이의 성충 밀도 변이 양상도 상관성이 높았다. 복숭아명나방 유인에서는 포획수가 너무 적어 평가가 불가능하였다. 이상의 결과에서 복숭아순나방과 복숭아심식나방 혼합미끼는 예찰에 이용할 수 있을 것으로 추정되었다.

페로몬에 기반한 해충방제 기술은 페로몬이 동정되는 곤충의 수가 지수적으로 증가함에 따라 더욱 성공가능성이 높은 전략이 되고 있다. 이 연구는 애기유리나방, [Synanthedon tenuis (Butler) (Lepidoptera: Sesiidae)]의 성페로몬((Z, Z )-3, 13-octadecadien-1-ol.)에 의한 화학 통신교란(pheromone-mediated chemical communication disruption, PCD)의 효과에 대한 것이다. 본 PCD법은 우리나라 전남 순천과 경 남 진주의 2곳의 단감 과수원에서 2016년과 2017년에 총 4회 수행되었으며, PCD의 효과는 성페로몬 처리구와 무처리구에서의 평가용 트랩 포 획수로 나타내었다. 성페로몬 처리구의 평가용 트랩에 유인된 수컷 성충수는 무처리구에 유인된 수보다 유의하게 적었으며, 유인수 감소효과는 95.2~100% (평균 98.8±1.2%)이었다. 이러한 결과로 볼 때 성페로몬에 기반한 애기유리나방의 방제가 가능할 것으로 판단된다

북한은 2017년 9월 3일 풍계리 핵실험장에서 6차 지하 핵실험을 단행하였다. 이전에 수행했던 핵실험들과 달리 풍계리 핵 실험장 주변에서 몇 차례의 유발지진이 발생하였고 이로 인해 지하에 갇혀 있던 방사성제논이 대기 중으로 방출되는데 영향을 끼쳤을 것으로 예상된다. 본 연구에서는 북한의 6차 핵실험 이후에 발생한 유발지진을 고려하여 핵실험으로 발생한 방사성제논의 몇 가지 방출 시나리오에 따른 대기확산 모의실험을 본 연구진이 개발한 LADAS (Lagrangian Atmospheric Dose Assessment System) 모델에 기상청의 수치예보자료를 적용하여 수행하였다. 방사성제논의 가능한 검출 위치와 시간을 찾기 위해, 1일 간격 및 1주일 간격의 지연방출뿐만 아니라 유발지진으로 유출된 지연방출 시나리오도 설정하였다. 포괄 적핵실험금지조약기구(Comprehensive Nuclear-Test-Ban Treaty Organization)에서 운영중인 전세계관측망(International Monitoring System)과 원자력안전위원회의 133Xe 탐지 결과는 유발지진으로 유출된 방사성제논의 방출 시나리오에 따른 모의실험의 결과와 대체로 부합되었다.

The use of printing inks containing organic solvents by the master, offset and screen printing process implies the release of volatile organic compounds (VOCs) to the work environment. In this study, the volatile content of inks was evaluated by using a thermogravimetric analyzer (TGA), in which the solvent is evaporated. And, to identify the the characterization of VOCs emissions from printing inks, air samples were collected in a thermal extractor (TE) and analyzed by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). Weight loss curves suggest that there are two main stages, such as dry fastening and chemical curing. As the result, the first stage of mass loss (below 100oC) was due to VOC evaporation. At this stage, master and offset inks are slightly stable thermally up to 100oC, but screen inks weight loss increases distinctly beyond 25oC. The volatile content is higher in screen inks than in the master and offset inks. The results of the mass-specific TVOC emission rate of the master, offset, and screen inks were 6.3 μg/(g·h), 8.4 μg/(g·h), and 212.2 μg/(g·h), respectively. Then the TVOC emission rate of the screen inks was 25~33 times higher than that of the master and offset inks. The main species were 1-Ethyl-2-pyrrolidinone, 1,2,4-Trimethylbenzene, 1,2,3-Trimethylbenzene, 1,2,4,5-Tetramethylbenzene, 1-Methoxy-2- propanol, Decane, Undecane, and Nonane.

본 연구에서는 정부의 고추 비축물량 방출이 냉동고추 수입에 어떠한 영향을 미치는지를 분석하고자 하였다. 벡터자기회귀모형 추정과 그랜저 인과성 검정의 주요 결과는 다음과 같다. 첫째, 정부 보유물량의 방출이 냉동고추 수입억제에 큰 영향을 미치지 못하고 있다는 점이다. 정부 보유물량을 특정 시점에 520여 톤 시장에 방출할 경우 냉동고추 수입량은 약 440톤 정도(건고추 환산 88톤) 감소하는 것으로 나타났다. 둘째, 국내 도매가격은 냉동고추 수입량에만 영향을 미치는 일방향성 인과관계를 갖는다는 것이다. 충격반응함수 추정결과에 따르면 특정 시점에 도매가격이 730원 정도 상승하면 냉동고추 수입량은 약 440여 톤(건고추 환산 88톤) 증가하지만, 냉동고추의 수입량이 5,100여 톤(건고추 환산 1,020톤) 증가하더라도 국내 도매가격은 35원 감소하는 데 그치고 있다. 셋째, 정부 방출물량은 국내 도매가격의 안정화에 일정 수준 영향을 미치고 있다는 점이다. 특정 시점에 정부 방출물량이 520여 톤 증가하면, 도매가격은 220원 정도 하락하는 것으로 나타났다. 이상과 같은 연구결과를 토대로 볼 때 정부의 국내산 건고추 비축물량과 Tariff Rate Quotas의 운영은 냉동고추 등 고추 관련 품목의 수입억제에 초점을 맞추기보다는 국내 가격안정에 초점을 두고 운영하는 것이 바람직하다고 판단된다.

악성 담도 폐쇄 환자에서 담즙 배액술은 환자의 생존이나 삶의 질 향상을 위하여 필요하다. 과거에는 수술이 주된 치료법이었으나 최근에는 내시경이나 경피적으로 스텐트 삽입술이 주된 치료법으로 인정되고 있다. 담도 스텐트의 개통기간을 증가시키기 위하여 다양한 소재와 구조가 고안되고 개발되었다. 이러한 스텐트 개발에 있어 화학적으로 피막 재질의 변화를 통하여 스텐트 내 종양 성장을 억제하여 스텐트 개통기간을 증가시키고자 항암담지스텐트가 대두되었다. 항암담지스텐트는 여러 동물실험과 임상시험을 통하여 안전성은 증명되었으나 유효성은 증명되지 못하였다. 현재까지 임상적 적용이 시도된 항암담지스텐트의 개발 과정과 문제점, 향후 연구방향에 대하여 논하고자 한다.

The purpose of this study is to investigate the ELF-MF emissions from UCLs and to compare the ELF-MF emission levels of HVTLs and UCLs. In addition, this study proposes a method and management plan to investigate the effects of exposure to ELF-MF emissions from UCLs. The ELF-MF emissions from the 154 kV UCL were 15.4±24.4 (GM: 7.8)mG, while from the 345 kV line they were 6.0±2.4 (GM: 5.7)mG. Through the comparison between ELF-MF emissions of 154 kV UCL and HVTL, at about 20 m distance from an overhead line the emissions level is 4 mG, while from an underground line at about 10 m distance the emission level was recorded as less than 4 mG. Through comparing the ELF-MF emission amount of the UCL according to the burial method, it was found that the direct ELF-MF emission levels are 15.3±7.4 (GM: 13.9)mG at the direct point, in the conduit type 21.0±30.4 (GM: 10.8)mG, and in the buried form 8.5±12.3 (GM:5.1)mG. In this study, ELF-MF emissions were about 37.0% and 47.5% lower, respectively, compared with the direct power and conduit type. The correlation between ELF-MF emission (mG) and power load (A) was analyzed. The higher the power load, the higher the ELF-MF emission. The correlation between ELF-MF emission at the direct point and depth of the UCL was also analyzed, and it was found that as the depth of line burial increased, ELF-MF emissions decreased.

최근 한국에서 원전해체는 중요한 이슈이다. 원전의 운영 시와 비교해볼 때, 원전 해체 시에는 방사성물질의 방출이 크지 않을 것으로 예상되지만, 주민은 항상 방사선피폭으로부터 보호되어야 한다. 이에 대한 효과적인 관리를 위해, 연간 방출관리치와 방출한도치를 원자력안전위원회 고시 및 일반인 선량한도 기준으로부터 유도하였다. 기체상 유출물에 의한 대기 확산 및 침적 인자는 신고리 발전소 기상탑에서 2008년부터 2010년까지 3년간 수집 된 기상자료를 토대로 XOQDOQ 컴퓨터 코드를 이용해서 평가하였다. 선량평가는 ENDOS-G 컴퓨터 코드를 사용하였다. 이 컴퓨터 코드를 이용하여 기체상 유출물의 연간 방출관리치 및 방출한도치를 평가한 결과, 핵종별로 차이가 있었는데, 이는 연령에 따른 방사선민감도의 차이에 기인한다고 할 수 있다. 본 평가 방법 및 결과는 향후 원전 해체 시 방사성유출물 관리에 중요한 정보를 제공할 수 있을 것으로 판단된다.

To extend the shelf-life of chicken breast meat, samples were treated with gel-packs containing slow-released ClO2 gas at 7-15 ppm for 8 days at 4℃. And the changes in lipid oxidation and taste compounds of the samples were investigated. TBARS value of the chicken breast was slightly increased during storage. TBARS value of gas treatments was similar to the control during storage. There were 14 fatty acids in the chicken breast. And there was no change in the fatty acid composition during storage, and there was no significant difference between the control and gas treatments. The content of free amino acids was gradually increased during storage. The content of free amino acids were not significantly different between the control and gas treatments during storage. The content of GMP in the control and gas treatments were decreased during storage. However, gas treatments showed slightly higher content than that of control. AMP was not significantly different between the control and gas treatments. IMP gradually decreased during storage and the content of inosine and hypoxanthine was increased. IMP, inosine and hypoxanthine contents of gas treatment were similar to control, but the control tended to change more rapidly than those of gas treatments.