The purpose of this study is to develop a pH measurement system capable of measuring the acidity of saliva to check the change in pH level in saliva during driving and to detect whether fatigue is affected. When the pH level is checked at rest and operation, and oxygen concentration is supplied additionally, it will be verified whether the fatigue is reduced. It is reported that the pH level in saliva is divided into stages from 0 to 14, and the lower the value based on step 7, the higher the fatigue, and the lower the fatigue. In particular, in enclosed vehicles, drowsiness and fatigue due to increased carbon dioxide have increased, leading to a major cause of traffic accidents. Therefore, fatigue may be detected in advance by analyzing fatigue through a change in pH level by supplying oxygen during operation. The electromotive force generated by the existing itself is a level of several mV to develop a pH measurement system, so it is developed by expanding it to a range that can be measured using a readout circuit. In the experiment, 13 male experimenters in their 20s measured pH levels in resting and driving conditions. After 20 minutes of rest, the process of inhaling oxygen for 20 minutes was repeated three times. The oxygen concentration used in the experiment was 21% oxygen and 30% oxygen concentration in the atmospheric state, and in the oxygen supply method, a triangular flask was directly connected to the subject’s nose and then oxygen was supplied. As a result of collecting and analyzing saliva after rest and operation, it was confirmed that the pH level tended to decrease in the operating state. In addition, as a result of increasing the pH level when the oxygen concentration is 30% more than 21%, it is confirmed that fatigue tends to decrease as the oxygen concentration increases. Therefore, it was possible to confirm a significant change in fatigue by analyzing the pH level of saliva through this pH measurement system. This study can be used as a fatigue test in various environments through simple pH measurement.

본 연구는 난방 개시 온도와 CO2 시비의 효율을 알아보기 위해 수행되었다. 난방 개시 온도 실험은 9℃, 12℃, 15℃로 구분하여 목표 온도보다 낮아지면 전기 온열기구가 작동하게 하였다. CO2 시비 농도 실험은 액화탄산가스를 이용하여 무 처리, 500μmol·mol-1, 800μmol·mol-1으로 7시부터 12시까 지 처리하였다. 생육 특성으로 초장, 경경, 엽수, 엽면적, 생체 중, 건물중을 조사하였고, 200g 넘는 과실만을 대상으로 수량 을 조사하여 경제성 분석을 하였다. 상위엽에 대한 광합성 측 정을 하여 처리에 따른 포화점을 산출하였다. 애호박의 광포화 점은 587μmol·m-2·s-1이였고 CO2 포화점은 702μmol·mol-1 이 였다. CO2에 의한 Amax값은 9℃, 12℃, 15℃, 500μmol·mol-1, 800μmol·mol-1 순으로 13.4, 17.8, 17.2, 19.6, 17.5μmol CO2·m-2·s-1이었다. 온도 실험에서 9℃는 생육과 착과가 정상 적으로 이루어지지 않았다. 12℃와 15℃는 9℃보다 높았지 만 생육과 생산에서 유의미한 차이를 보이지 않았다. CO₂ 농 도 실험은 생육에서 처리구간 유의한 차이를 보이지 않았지만 800μmol·mol-1의 생산성이 가장 좋았다. 이상의 결과를 종합 적으로 보면 난방 개시 온도는 15℃인 것은 작물 생육과 생산 에는 좋았지만 12℃와 유의적인 차이가 없어 경제적 측면에 서 난방 개시 온도를 12℃로 설정하는 것이 좋은 것으로 보이 며, CO2 시비 농도 800μmol·mol-1를 유지하는 것이 생산량 증가에 효과적이었다.

We report the synthesis and gas sensing properties of bare and ZnO decorated TeO2 nanowires (NWs). A catalyst assisted-vapor-liquid-solid (VLS) growth method was used to synthesize TeO2 NWs and ZnO decoration was performed using an Au-catalyst assisted-VLS growth method followed by a subsequent heat treatment. Structural and morphological analyses using X-ray diffraction (XRD) and scanning/transmission electron microscopies, respectively, demonstrated the formation of bare and ZnO decorated TeO2 NWs with desired phase and morphology. NO2 gas sensing studies were performed at different temperatures ranging from 50 to 400 oC towards 50 ppm NO2 gas. The results obtained showed that both sensors had their best optimal sensing temperature at 350 oC, while ZnO decorated TeO2 NWs sensor showed much better sensitivity towards NO2 relative to a bare TeO2 NWs gas sensor. The reason for the enhanced sensing performance of the ZnO decorated TeO2 NWs sensor was attributed to the formation of ZnO (n)/ TeO2 (p) heterojunctions and the high intrinsic gas sensing properties of ZnO.

Kr-85 has a half-life of 10.7 years and it stays in the atmosphere for a long time. However it does not accumulate as an noble gas but only emits beta particles. Therefore its contribution to environmental radiation dose is lower than any other radionuclides. Kr-85 is one of the main fission products produced by nuclear fission reaction and artificial radionuclide that does not exist in nature. For these reasons, monitoring Kr-85 from the atmosphere is meaningful so that the nuclear-related facilities are recommended to control and regulate environmental emissions. Post Irradiation Examination Facility (PIEF) which located in KAERI is a facility that conducts various material and chemical experiments using the irradiated nuclear fuels. Therefore, various radionuclides can present in gaseous effluent including Kr-85. To prevent the environmental hazards and guarantee the radiation safety of the public, nuclear facilities are recommended to be equipped with stack radiation/radioactivity monitoring system, so that the Kr-85 concentration in gaseous effluent is controlled within the regulatory criteria. Particularly, the Kr-85 concentration of gaseous effluent is commonly monitored by the stack monitoring system connected to the process ventilation system from the hot cell. The monitoring system supply the information such as beta count rate, dose rate and flow rate, etc. Due to the concentration of Kr-85 in gaseous effluent is subject to regulatory guide lines, a systemized procedure for calculating Kr-85 concentration of the stack exhaust is necessary. Furthermore, the emission should be monitored whether it satisfies the regulatory standard or does not. This paper performed discussion on the process of calculating the concentration of Kr-85 in the gaseous effluent of PIEF stack from the monitoring system (NGM209, MGP), and the amount of Kr- 85 over the last 2 years emissions was calculated. In addition to calculating effluent rate of radioactive Kr-85, the Minimum Detectable Concentration (MDC) and Decision Threshold (SD) were calculated. As a result, the calculated Kr-85 concentration was below the SD during the entire period. It is considered that there are no environmental emissions of Kr-85.

In 2018, media reports raised issues related to radon released from building materials used as finishing materials in apartment houses. Accordingly, related ministries recommended not to use materials with a radiation index value exceeding 1. In order to calculate the radioactivity index, not only 226Ra producing radon (222Rn) but also 232Th and 40K radioactivity concentrations are required. To determine the concentration of the radionuclide, 40K is measured by a single gamma ray of 1,460.8 keV. And the 228Ac used to measure 232Th mainly utilizes gamma rays of 911.2 keV. However, 228Ac does not appear as a single peak unlike 40K, and appears as multiple peaks at various energies. Among them, gamma rays are emitted at a intensity of 0.83% at 1,459.2 keV, which is likely to interfere with 40K. Therefore, what is actually measured at 1,460.8 keV is theoretically a compound peak of 40K and 228Ac. Because the probability of emission at 1,459.2 keV (0.83%) is low, a low concentration of 232Th will result in little 40K radioactivity error. However, samples containing a high concentration of 232Th overestimate the 40K radioactive concentration, so correction is required. In this study, the IAEA standard substance (IAEA-RGTh-1) ontaining 232Th of actual high concentration was analyzed, and the results of the analysis without correction of 40K were compared and verified. As the 40K correction method, the 911.2 keV gamma-ray of 228Ac was used as the reference peak to separate the peak of 228Ac (1,459.2 keV) from the 40K (1,460.8 keV) mixed peaks. And, the coefficient value obtained by subtracting the peak of 228Ac (1,459.2 keV) from the 40K (1,460.8 keV) mixed peak was set to a pure peak of 40K and the radioactivity concentration was calculated therefrom. As a result of calculating the IAEA-RGTh-1 reference material without correction, it was confirmed that the 40K value was overestimated by about 38 times. If a measurement beyond the MDA of 40K is generated by 228Ac radioactivity because the 40K correction constant is not applied, there is an error in determining that there is 40K radioactivity. However, even if 40K radioactivity is overestimated due to the high concentration of 232Th, the degree to which this effect contributes to the radioactivity index is very small. However, as an analyst, 40K radioactivity correction should be made for more accurate analysis.

Radioactive waste is classified into Intermediate level, low level, and very low potential based on the amount of radioactivity per unit gram, that is, the concentration limit. This method of classifying radioactivity per unit weight is not a problem if all packaged wastes are homogeneous. However, the reality is that not all waste is homogeneous. Relative hotspots may exist. Also, when several items are mixed, if one item has a relatively higher concentration than other items, it can become a relative hotspot. In Korea, even if all nuclides in a single radioactive waste package satisfy the low level concentration limit, if even one nuclide exceeds the concentration limit, the radioactive waste package becomes the intermediate level. In case of the United States, the US NRC provides regulations related to obtaining license as well as presents the technical position on the average waste concentration called Concentration Averaging and Encapsulation Branch Technical Position (CA BTP). CA BTP classifies waste into four types : Blendable Waste, Encapsulated items, Single Discrete Items, and Mixture of Discrete Items, and presents each approach to concentration averaging. In general, this is a method that suggests an acceptable ratio in case of the waste, which relatively high concentration waste is mixed. In order to apply this in Korea, we compare the classification standards for low and Intermediatelevel waste in Korea and the United States, related laws and backgrounds, and the application methods of CA BTP.

Montmorillonite plays a key role in engineered barrier systems in the high-level radioactive waste repository because of its large sorption capacity and high swelling pressure. However, the sorption capacity of montmorillonite can be largely varied dependent on the surrounding environments. This study conducted the batch simulation for U(VI) sorption on Na-montmorillonite by utilizing the cation exchange and surface complexation coupled (2SP-NE-SC/CE) model and evaluated the effects of physicochemical properties (i.e., pH, temperature, competing cations, U(VI) concentration, and carbonate species) on U(VI) sorption. The simulation demonstrated that the U(VI) sorption was affected by physicochemical properties: the pH and temperature relate to aqueous U(VI) speciation, the competing cations relate to the cation exchange process and selectivity, the U(VI) concentration relates to saturation at sorption sites. For example, the Kd (L kg−1) of Na-montmorillonite represented the largest values of 2.7×105 L kg−1 at neutral pH condition and had significantly decreased at acidic pH<3, showing non-linear and diverse U(VI) sorption at the ranged pH from 2 to 11. Additionally, the U(VI) sorption on montmorillonite significantly decreased in presence of carbonate species. The U(VI) sorption for long-term in actual porewater chemistry and temperature of high-level radioactive waste repository represented that the sorption capacity of Na-montmorillonite was affected by various external properties such as concentration of competing cation, temperature, pH, and carbonate species. These results indicate that geochemical sorption capacity of bentonite should be evaluated by considering both geological and aquifer environments in the high-level radioactive waste repository.

This study measured the suspended fungal concentration in indoor multiple facilities nationwide. The regions were selected as representative cities by region: Seoul, Gyeonggi (Incheon), Gangwon, Gwangju, Daejeon, and Busan. A total of 2028 regional comparisons, including department stores, schools, public toilets, libraries, and banks, subway, sports facilities and comparative analysis were conducted for each multi-use facility industry. Among the nationwide, Among the regions, the average concentration of floating mold in indoor multi-use facilities was the lowest in Busan at 394.67 CFU/m3, followed by Gyeonggi and Incheon 487.90 CFU/m3, Seoul 542.84 CFU/m3, Daejeon 809.30 CFU/m3, Gangwon 1,145.22 CFU/m3, Gwangju was 1,371.10 CFU/m3 in the order. Busan was the lowest, and Gangwon was the highest. The reason that Busan, which has a high average temperature and population density, shows a lower mold concentration than Gangwon, is that floating mold in the indoor air is not affected by the external atmospheric environment, population density, and number of facility users. Although it cannot be said that there is no influence of the atmospheric environment, it was found that the indoor environment has different characteristics from the outdoor environment. The importance of air quality management has been confirmed, and further, it is necessary to subdivide the management standards by region and multi-use facilities, and the management standards need to be converted to maintenance rather than recommendations.

Double-layer capacitors (DLCs) are developed with high surface electrodes to achieve a high capacitance value. In the present work, the initial bulk concentration of 1 mol/m3 and 3 mol /m3 are selected to show the consequential effects on the performance of a double-layer capacitor. A 1D model of COMSOL Multiphysics has been developed to analyze the electric field and potential in cell voltage, the electric displacement field and polarization induced by the field, and energy density in a double-layer structure. The electrostatics and the electric circuit modes in COMSOL are used to simulate the electrochemical processes in the double-layer structure. The analytical analysis of a double-layer capacitor with different initial bulk concentrations is investigated by using Poisson-Nernst-Plank equations. From the simulation results, the differential capacitance changes as a function of compact layer thickness and initial bulk concentration. The energy density varies with the differential capacitance and voltage window. The values of energy density are dominated by the interaction of ions in the solution and electrode surface.

This study explored the possibility of forming a coating layer containing alginic acid on the surface of a magnesium alloy to be used as a biomaterial. We formed a coating layer on the surface of a magnesium alloy using a plasma electrolytic oxidation process in an electrolytic solution with different amounts of alginic acid (0 g/L ~ 8 g/L). The surface morphology of all samples was observed, and craters and nodules typical of the PEO process were formed. The cross-sectional shape of the samples confirmed that the thickness of the coating layer became thicker as the alginic acid concentration increased. It was confirmed that the thickness and hardness of the sample significantly increase with increasing alginic acid concentration. The porosity of the surface and cross section tended to decrease as the alginic acid concentration increased. The XRD patterns of all samples revealed the formation of MgO, Mg2SiO4, and MgF2 complex phases. Polarization tests were conducted in a Stimulate Body Fluid solution similar to the body's plasma. We found that a high amount of alginic acid concentration in the electrolyte improved the degree of corrosion resistance of the coating layer.

This study aims to investigate the proper mixing treatment concentration of ozone (O3) and sucrose to preserve and extend the vase life of the cut rose flowers ‘Dominica’. The vase solution was prepared using tap water, 3% sucrose, ozone 5.5 mg L-1, and 3% sucrose with ozone 5.5 mg L-1. The vase life was the highest in the tap water and ozone treatments at 16.3 and 16.1 days, respectively. The vase life of ozone with sucrose treatment was 6.9 days, which was 9.4 days lower than that of the control. Compared to a single treatment, the vase life termination symptoms for ozone with sucrose treatment decreased petal wilting and increased bent necks. Relative fresh weight and vase solution uptake increased up to 4 days after treatment and decreased from 2 days before vase life termination. The rate of change in petal color was high in L*, a*, and b* for the sucrose treatment than after harvest, and low for the ozone treatments. The maximum relative flower size increase rates after treatment were 195% in the control, 186% in the sucrose treatment, 171% in the ozone treatment, and 155% in the ozone with sucrose treatment.

복숭아는 대표적인 여름 과일이자 알레르기를 유발하는 식품으로 밀폐되고 집약적인 생산환경으로 인해 시설 내 유기분 진, 농약, 복숭아털이 발생하기 때문에, 열악한 작업환경으로 인한 작업자들이 어려움을 많이 겪고 있다. 본 연구에서는 복 숭아 선별작업장에서 발생하는 미세먼지를 위치별, 작업별, 입경별로 모니터링함으로써 저감 및 대책 마련을 위한 기초자 료를 확보하고자 하였다. 미세먼지 모니터링 결과 지역별로 는 선별과정에서 미세먼지의 발생이 높은 것으로 나타났으며, 주로 기계적인 과정을 통하여 발생하는 10μm 이상의 미세먼 지로 나타났다. 본 연구를 바탕으로 향후 작업환경의 개선을 위해서 공정 중 미세먼지가 주로 발생하는 지역 및 미세먼지 의 물리적 특성을 고려하여 저감시설 및 개인보호구의 착용이 요구된다.

이번 연구는 효과적으로 2화방 개화묘를 생산하여 조기에 토마토를 수확하고 수확 기간을 연장하기 위하여 적절한 양액 농도 관리방법을 구명하기 위해 실시되었다. 처리는 양액 농도 로 1줄기 2화방 개화묘 연구에서는 양액 EC를 1.5, 2.0, 2.5dS·m-1, 동적 관리(3.0 → 3.5 → 4.5dS·m-1)로 공급하였다. 육묘기간은 65일로 관행묘에 비해 20－40일, 1화방 개화묘 (큐브 육묘)보다는 10일 정도 길었다. 초장은 EC 2.5dS·m-1와 동적 관리는 각각 78, 77cm로 EC 1.5dS·m-1처리 88cm보다 짧았다. 정식 전 큐브 내 EC는 동적 관리가 EC 5.5dS·m-1로 가 장 높았으며, EC 1.5dS·m-1로 공급한 큐브는 3.0dS/m으로 가 장 낮았다. 2화방 개화묘에서 EC 처리 간 생산량 차이는 나타 나지 않았으나 1화방 개화묘는 2화방 개화묘보다 생산성이 떨 어졌다. 2화방 개화묘는 첫 수확일이 6월 4일로 정식 후 35일 만에 수확하였으며 1화방 개화묘는 6월 11일로 42일만에 수 확하였다. 절곡에 의한 초장 및 뿌리 생육의 차이는 나타나지 않았다. 2줄기 2화방 개화묘 생산 연구에서는 공급 양액 EC를 2.0, 2.5, 3.0dS·m-1, 동적 관리(3.0 → 3.5 → 4.5dS·m-1)로 하 여 공급하였다. 육묘 기간은 90일로 관행묘에 비해 40－50일, 1화방 2줄기 개화묘(큐브 육묘)보다는 10일 정도 길었다. 초장 은 공급 양액 EC 2.0dS·m-1에서 80cm, 2.5dS·m-1에서는 81cm였으며 3.0dS·m-1 처리에서는 75cm, 동적 관리에서는 73cm로 가장 짧았다. 배지 내 EC는 모든 처리에서 육묘 기간 이 길어질수록 높아졌으며 특히 공급 EC가 가장 높았던 동적 관리 처리에서 EC 5.1dS·m-1로 가장 높았다. EC 처리 간 생산 량 차이는 나타나지 않았으나 육묘 기간이 10일 정도 길었던 2 화방 개화묘가 1화방 개화묘보다 15% 정도 생산량이 많았다. 2화방 개화묘의 초장을 짧게 만들기 위해서는 가식 후 공급 양 액 농도를 높이는 방법이 가장 효율적인 방법으로 판단된다.

본 연구는 환경측정용 센서 위치에 따른 온실 환경의 공간· 수직적 특성을 조사하고 온실 종류에 따른 온도, 광도 및 CO2 농도 간의 상관관계를 구명하고자 수행하였다. 벤로형 온실의 공간적인 5지점을 선정한 후 각 지점에서 대표적 작물의 수 직적 높이 4지점과 지면부, 지붕 공간에 온도, 상대습도, CO2, 엽온 및 광센서를 설치하였다. 벤로형 온실과 반밀폐형 온실 에서 온도, 광도 및 CO2 농도 변화의 관계성을 Curve Expert Professional 프로그램을 이용하여 비교하였다. 벤로형 온실 의 공간적 위치에 따른 편차는 CO2 농도가 다른 요인보다 큰 것으로 나타났다. CO2 농도는 평균 465－761μmol·mol-1 범 위였고, 편차가 가장 큰 시간대는 오후 5시였으며, 최고 농도 는 액화 탄산가스 공급장치의 메인 배관(50∅)과 가까운 위치 인 중앙 후부(Middle End, 4ME)에서 646μmol·mol-1, 최저 농도는 좌측 중앙(Left Middle, 5LM)에서 436μmol·mol-1이 었다. 수직적 위치에 따른 편차는 온도와 상대습도가 다른 요 인보다 큰 것으로 나타났다. 평균 기온의 편차가 가장 큰 시간 대는 오후 2시대이며, 최고 기온은 작물 위 공기층(Upper Air, UA)에서 26.51℃, 최저 기온은 작물의 하단부(Lower Canopy, LC)에서 25.62℃였다. 평균 상대습도의 편차가 가장 큰 시간 대는 오후 1시대로 나타났으며, 최고 습도는 LC에서 76.90%, 최저 습도는 UA에서 71.74%이다. 각 시간대에 평균 CO2 농 도가 가장 높은 수직적 위치는 지붕 공간 공기층(Roof Air, RF)과 시설 내 지면(Ground, GD)이었다. 온실 내 온도, 광도 및 CO2 농도의 관계성은 반밀폐형 온실의 경우 결정계수(r2) 가 0.07, 벤로형 온실은 0.66이었다. 결과를 종합하여 볼 때, 온실 내 CO2 농도는 공간적 분포, 온도와 습도는 작물의 수직 적 분포 차이를 측정하여 분석할 필요가 있고 환기율이 낮은 반밀폐형 온실의 경우 목표 CO2 시비 농도가 일반 온실과 다 르게 설정해야 할 것으로 판단된다.

Microcystins (MCs) are cyano-toxins mainly produced by cyanobacteria in the genera of Microcystis, Anabaena, and Oscillatoria. The concentrations of MCs in the water bodies and fish tissues taken from the four weirs (Ipo, Gangjeong-goryeong, Baekje, and Juksan) in the four main rivers in Korea, and the health risk of human due to consumption of toxin-detected fish was examined. The maximum values of MCs concentration in the water samples were as follows: Juksan (3.261 μg L-1), Gangjeong-goryeong (1.014 μg L-1), Baekje (0.759 μg L-1), and Ipo (0.266 μg L-1) weirs. The MC-RR concentration was the highest among the MCs, and MC-YR was not detected. MCs of 0.222~9.808 μg g-1 dry weight were detected in the liver of 3 out of 215 fishes of 16 species, and below the detection limit in muscle. As a result of comparing the feeding characteristics of the collected fishes and toxin concentrations in water and fish tissue, it was concluded that the biomagnification of MCs through the food chain did not occur. It was judged that there was no health risk due to the consumption of the fish detected the toxin, based on the amount of the fish intake of the Korean people and the allowable daily intake of MCs. However, in order to reduce the health risk due to MCs, further studies should be conducted to analyze the concentration of MCs contained in fish tissues collected at various times in the area dominated by harmful cyanobacteria to obtain data on the exposure of MCs due to fish consumption. In addition, it is necessary to establish the management guidelines for MCs in fish tissues.