Biocide dichlofluanid breaks down quickly and accumulates easily in sediment, potentially causing a persistent impact on various marine organisms. We analyzed the potential toxicity of dichlofluanid on major aquaculture species in Korea, Undaria pinnatifida. Female gametophytes of U. pinnatifida were exposed to dichlofluanid at concentrations of 0, 1, 2, 4, 8, 16, and 32 mg L-1, and their survival and relative growth rate were analyzed. The no observed effect concentration (NOEC), lowest observed effect concentration (LOEC), and median lethal concentration (LC50) for female gametophyte survival were determined as 1, 2, and 10.82 (95% CI: 8.87-13.23) mg L-1, respectively. The NOEC, LOEC, and median effective concentration (EC50) for relative growth rate were 1, 2, and 6.58 (95% CI: 6.03-7.17) mg L-1, respectively. Female gametophytes of U. pinnatifida were expected to experience toxic effects at concentrations above 2 mg L-1 of dichlofluanid. These research findings are expected to serve as important reference data for evaluating the toxicity effects of U. pinnatifida in its early life stages when exposed to dichlofluanid.

Ring Tensile Test (RTT) is mainly performed for comparing tensile strength and total strain between nuclear fuel cladding specimens under various initial conditions. Through RTT, the loaddisplacement (F-D) curve obtained from the uniaxial tensile test can also be obtained. However, the Young’s modulus estimated from the gradient of the straight portion is much lower than general value of materials. The reasons include tensile machine compliance, slack in the fixtures, or elastic deformation of the fixtures and the tooling. Another reason is that the bending of the test part in the ring is stretched with two pieces of tools. Although the absolute value of the Young’s modulus is smaller than the actual value, it is applicable to calculate the ratio of the Young’s moduli of different materials, that is, the relative value. The Young’s modulus, or slope of the linear section, varies slightly depending on which location data is used and how much data is included. In order to obtain a more accurate ratio of Young’s moduli between materials using the RTT results, a post-processing method for the ring tensile test results that can prevent such human errors is proposed as follows. First, the slope of the linear section is obtained using the displacement and load when the load increase is the largest and the displacement and load of the position that is 95% of the maximum load increase. To replace the section where the ring-shaped specimen is stretched at the beginning of the F-D curve, a straight line equal to the slope of the linear section is drawn to the displacement axis from the position of maximum load increase and moved to the origin to obtain the final F-D curve for a RTT. Lastly, the yield stress uses the stress at the point where the 0.2% offset straight line and the F-D curve meet as suggested in the ASTM E8/E8M-11 “Standard test methods for tensile testing of metallic materials”. RTT results post-processing method was coded using FORTRAN language so that it could be performed automatically. In addition, sensitivity analysis of the included data range on the Young’s modulus was performed by using the included data range as 90%, 85%, and 80% of the maximum load increase.

The International Atomic Energy Agency (IAEA) Safety Fundamentals No. SF-1 Safety Principle 7 states that people and the environment, present and future, must be protected against radiation risk. Therefore, it is important to evaluate the safety of radioactive waste repositories on a longterm time scale to ensure future safety. However, IAEA-TECDOC-767 states that the long-term time scale of interest means that the risk or dose to future individuals cannot be reliably predicted because it relies on assumptions. Therefore, evaluating the safety of long-term time scales should use safety indicators that are less dependent on assumptions. Radiotoxicity is one of the safety indicators that represent an inherent risk from radioactive waste. It has been mainly used to show the time required until the hazard presented by waste decreases to that of natural uranium ore and is easy to use in communication with the public. There are several methods for calculating Radiotoxicity. Radioactivity is multiplied by a Dose Conversion Factor (DCF) to be expressed in Sv units, or radioactivity be divided into Maximum Permissible Concentration (MPC) to be expressed in m3 units as the amount of water needed to dilute the radionuclide to the permitted level. It is also often made dimensionless through comparison with reference materials like uranium ore. Radiotoxicity varies in size several times, even if it is a waste of similar origins and components, depending on the Radiological variable (e.g., Annual Limitation Intake (ALI), Dose Conversion Factor (DCF), Maximum Permissible Concentration (MPC), Activity). Therefore, this study was conducted to determine whether there was a significant difference when different radiological variables were substituted. This study compares and analyzes their differences using various MPCs or DCFs used in each country. In addition, this study analyzes radionuclides that influence radiotoxicity with several radiological variables. This study introduces the effects of substituting different radiological variables.

본 연구는 청년세대의 상대적 박탈이 사회적 이슈로 떠오르고 있음에 도 불구하고 관련된 사회적 논의와 학문적 연구가 제대로 이루어지지 못 하고 있다는 비판에 기반하고 있다. 이에 20~30대 청년을 대상으로 온라 인 설문조사로 데이터를 수집하여 위계적 회귀분석방법으로 청년세대의 상대적 박탈감에 영향을 주는 요인을 파악하였다. 연구 결과 및 논의를 다음과 같이 제시하고자 한다. 첫째, 한국 사회의 청년세대는 분배의 불 공정성에 기반해 상대적 박탈감을 체감하는 것으로 나타났다. 사회적 환 경과 맞물려 더욱 두드러지게 나타나는 분배공정성의 특성상, 공정하지 못한 분배구조로 인해 피해를 받고 있다는 청년세대의 상대적 박탈감 인 식은 일면 당연한 모습으로 해석된다. 둘째, 평등에 대한 인식이 분배공 정성과 결합한 상호작용의 효과로 상대적 박탈감을 낮추는 요인으로 작 용함을 알 수 있었다. 이와 같은 결과는 사회적 평등이 공정성을 강화시 키는 요소로 작용할 수 있음을 보여줌과 동시에 공정성의 다차원적 요인 에 평등이 포함될 수 있음을 보여주는 것이다. 결론적으로, 사회적 자원 에 대한 접근의 평등과 공정함을 제도로 보장하고 공평한 자원 분배 정 책 등이 최우선의 청년정책으로 마련되어져야 할 것이다.

Spodoptera species (S. exigua and S. litura) are important pests of several crops and vegetables in Korea. We investigated development processes of Spodoptera species under constant temperatures (20, 25 and 30 oC) regimes and relative humidity (RH) (30-35, 50-55, 70-75, and 90-95%) conditions. We collected eggs of Spodoptera species by releasing them into a rectangular box inner walls covered with a sheet of white paper. Temperature and RH significantly impacted on oviposition, immature survival, adult emergence and longevity of Spodoptera species. Maximum number of eggs, shorter developmental time, higher adult emergence with longer longevity were reported in 70-75% at 30 oC. Minimal eggs and larval survival were recorded in 30-35% and 90-95% RH, respectively. This results suggest that temperature and RH had individual apparent effect on the developmental processes of Spodoptera species instead interactive effect. Therefore, there is chance to cause a significant damage to field crops and vegetables in 70-75% at 30 oC.

닭 사체를 이용하여 장소, 기온, 습도별 시식성 곤충상을 파악하기 위해 대전광역시 전민동 일대의 3개의 장소 를 선택하여 닭 사체별로 유인되는 곤충의 종류와 군집 상의 차이와 출현양상을 조사하였다. 이를 위해, 닭 사체에 유인되는 곤충을 주기적으로 채집하고 해당 일자의 온도와 습도를 조사하여 기록했으며, 채집한 곤충들은 외부 형태적 특징으로 분류하고 개체수를 확인했다. 조사결과, 딱정벌레목과 파리목의 개체가 가장 많았고, 그 외에 바퀴목, 벌목, 노린재목 분류군에 속하는 다양한 곤충들이 유인된 것을 확인할 수 있었다. 본 연구 결과는 법곤충 시식성 곤충을 연구하는데 중요한 기초자료로 활용될 수 있도록 결과를 종합정리하였다.

Chlorothalonil is continuously introduced into the marine environment and has significant toxic effects on various marine organisms, however, research on its effect on seaweed is limited. Therefore, we analyzed the impact of chlorothalonil on the early life stages of major aquaculture species in Korea, Undaria pinnatifida. U. pinnatifida female gametophytes were exposed to different concentrations of chlorothalonil (0, 0.03, 0.05, 0.10, 0.20, and 0.40 mg L-1), and their survival rate and relative growth rate were analyzed. The no observed effect concentration (NOEC), lowest observed effect concentration (LOEC), and median lethal concentration (LC50) for female gametophyte survival were determined as 0.05, 0.10, and 0.141 (0.121-0.166) mg L-1. NOEC, LOEC, and median effective concentration (EC50) for relative growth rate were 0.10, 0.20, and 0.124 (0.119-0.131) mg L-1. Therefore, female gametophytes of U. pinnatifida are expected to experience toxic effects at concentrations above 0.05-0.10 mg L-1 of chlorothalonil. These research findings are anticipated to serve as crucial reference data for evaluating the effects of chlorothalonil on the health of U. pinnatifida in the early life stages.

This study was conducted with the aim of confirming the impact and relative contribution of extreme weather to dry matter yield (DMY) of silage corn in the central inland region of Korea. The corn data (n=1,812) were obtained from various reports on the new variety of adaptability experiments conducted by the Rural Development Administration from 1978 to 2017. As for the weather variables, mean aerial temperature, accumulated precipitation, maximum wind speed, and sunshine duration, were collected from the Korean Meteorological Administration. The extreme weather was detected by the box plot, the DMY comparison was carried out by the t-test with a 5% significance level, and the relative contribution was estimated by R2 change in multiple regression modeling. The DMY of silage corn was reduced predominantly during the monsoon in summer and autumn, with DMY damage measuring 1,500-2,500 kg/ha and 1,800 kg/ha, respectively. Moreover, the relative contribution of the damage during the monsoons in summer and autumn was 40% and 60%, respectively. Therefore, the impact of autumn monsoon season should be taken into consideration when harvesting silage corn after late August. This study evaluated the effect of extreme weather on the yield damage of silage corn in Korea and estimated the relative contribution of this damage for the first time.

Metal additive manufacturing (AM) has transformed conventional manufacturing processes by offering unprecedented opportunities for design innovation, reduced lead times, and cost-effective production. Aluminum alloy, a material used in metal 3D printing, is a representative lightweight structural material known for its high specific strength and corrosion resistance. Consequently, there is an increasing demand for 3D printed aluminum alloy components across industries, including aerospace, transportation, and consumer goods. To meet this demand, research on alloys and process conditions that satisfy the specific requirement of each industry is necessary. However, 3D printing processes exhibit different behaviors of alloy elements owing to rapid thermal dynamics, making it challenging to predict the microstructure and properties. In this study, we gathered published data on the relationship between alloy composition, processing conditions, and properties. Furthermore, we conducted a sensitivity analysis on the effects of the process variables on the density and hardness of aluminum alloys used in additive manufacturing.

This study aims to present a method to evaluate the relative risk of failure due to liquefaction of domestic small to medium-sized earthfill dams with a height of less than 15 m, which has little information on geotechnical properties. Based on the results of previous researches, a series of methods and procedures for estimating the probability of dam failure due to liquefaction, which calculates the probability of liquefaction occurrence of the dam body, the amount of settlement at the dam crest according to the estimation of the residual strength of the dam after liquefaction, the overtopping depth determined from the amount of settlement at the dam crest, and the probability of failure of the dam due to overtopping was explicitly presented. To this end, representative properties essential for estimating the probability of failure due to the liquefaction of small to medium-sized earthfill dams were presented. Since it is almost impossible to directly determine these representative properties for each of the target dams because it is almost impossible to obtain geotechnical property information, they were estimated and determined from the results of field and laboratory tests conducted on existing small to medium-sized earthfill dams in previous researches. The method and procedure presented in this study were applied to 12 earthfill dams on a trial basis, and the liquefaction failure probability was calculated. The analysis of the calculation results confirmed that the representative properties were reasonable and that the overall evaluation procedure and method were effective.

이 연구는 한일 양국 간 대학생이 서로의 문화에 대해서 어떤 계기로 관심을 갖게 되었는지, 어떠한 문화에 관심이 있는지에 대한 실태를 파 악하고자 하였다. 그 결과는 다음 세 가지로 요약된다. 첫째, 한국대학생 의 일본·일본문화에 대한 관심도는 상당히 높은 것으로 나타났다. 일본문 화에 처음 관심을 갖게 된 계기와 시기로는 초등학교, 중학교 때 접한 학생들이 많았으며, 주로 애니메이션을 통해서 접하였다. 고등학교 이후 에 관심을 갖게 된 학생은 학교에서의 일본어 수업이나 유튜브를 통한 일본 음식, 일본 여행을 통해서 관심을 갖게 되었다. 둘째, 국가 차원에 서의 한일관계는 현재는 부정적으로 생각하고 있으나, 미래에는 좋아질 것으로 판단하고 있다. 한일관계가 나쁜 원인으로 역사문제와 정치문제 에 기인하며, 이를 정치인들이 악용하여 해결보다는 갈등을 조장하고 있 으며, 한일관계가 좋아지기 위해서는 서로 간의 교류를 늘려서 원활한 대화가 필요하다고 생각하고 있다. 셋째, 민간 차원에서의 국가이미지와 한일관계는 긍정적인 것으로 나타났다. 한일 간의 관계가 악화되더라도 국가 간의 관계와 민간차원과의 관계는 별개로 보고 있다.

Determination of explosion reference pressure is important in designing and testing flameproof enclosures (Ex d). Although relative humidity affects to explosion pressure, its effect is not well investigated for the gas group IIB, IIA, and I. This study tested explosion pressure for Ethylene (8 vol.%), Propane (4.6 vol.%), and Methane (9.8 vol.%), which are the representative gas of the gas group IIB, IIA, and I, at ambient temperature and atmospheric pressure (1 atm) under different relative humidity (0% ~ 80%). Ethylene- and Propane-air mixed gases generally tended to decrease as the relative humidity increased; however, explosion pressure was largely dropped at 20% of relative humidity compared to 0% and 10% of relative humidity. On the other hand, Methane-air mixture gas showed similar pressures at 0% and 10% of relative humidity; but no explosion occurred at more than 20%. The results of this study can be used in setting a testing protocol of explosion reference pressure for designing and testing a flameproof enclosure.

To test a flameproof enclosure for the safety certificate, a reference pressure of explosion needs to be determined. However, the explosion pressure may be changed according to relative humidity of explosive gases. Therefore, the guideline on relative humidity should be recommended for measuring the explosion pressure for accurate and reproducible testings. This study examined the relationship of explosion pressure with relative humidity of hydrogen (31 vol %)-air and acetylene (14 vol %)-air mixture gases. The explosion pressures were measured by increasing the relative humidity of the gases by 10 % from dry state to 80 % in a cylindrical explosion enclosure of 2.3 L. on ambient temperature and atmospheric pressure (1 atm). The maximum explosive pressures were remained almost constant until the relative humidity reached 10 % for the hydrogen-air mixture and 20 % for the acetylene-air mixture. However, the maximum explosive pressures linearly decreased as the relative humidity increased. Based on the results of the study, it would be recommended to use 10 % relative humidity for the hydrogen-air mixture and 20 % for the acetylene-air mixture as the critical value in testing a flameproof enclosure.

미역(Undaria pinnatifida) 포자를 사용한 생태독성 시험법은 연중 상시 이용하기에 어렵다. 미역 의 암배우체는 실험실에서 배양할 수 있기 때문에, 포자의 단점을 보완하고 상시 생태독성 시 험에 사용할 수 있다. 따라서 미역의 암배우체를 생태독성 시험에 활용하기 위해 다양한 환경 조건에 노출된 미역의 암배우체 생존율과 상대성장률의 변화를 분석하였다. 미역 암배우체는 염분(5~40 psu), 온도(5~30℃), pH (2~10), 광량(0~120 μmol photon m-2 s-1)에 노출되었다. 암배 우체의 생존율은 최고 평균값을 기준으로 온도 20℃, 염분 27.5 psu, pH 8, 광량 30 μmol photon m-2 s-1에서 가장 높았다. 상대성장률은 최고 평균값을 기준으로 온도 15℃, 염문 35 psu, pH 9, 광량 60 μmol photon m-2 s-1에서 가장 높았다. 본 연구결과를 통해 미역 암배우체의 생존율과 상대성장률을 활용하여 연안환경을 상시 신속하게 평가하기 위한 효율적인 방법으로 활용이 기대된다.

A reliable prediction model of national occupational accident fatality rate can be used to evaluate level of safety and health protection for workers in a country. Moreover, the socio-economic aspects of occupational accidents can be identified through interpretation of a well-organized prediction model. In this paper, we propose a machine learning based relative comparison methods to predict and interpret a national occupational accident fatality rate based on socio-economic indicators. First, we collected 29 years of the relevant data from 11 developed countries. Second, we applied 4 types of machine learning regression models and evaluate their performance. Third, we interpret the contribution of each input variable using Shapley Additive Explanations(SHAP). As a result, Gradient Boosting Regressor showed the best predictive performance. We found that different patterns exist across countries in accordance with different socio-economic variables and occupational accident fatality rate.

This study evaluated the quality of school milk programs and analyzed the relative importance of school milk program selection attributes using conjoint analysis. The survey was conducted on students from middle and high schools in metropolitan cities that provide school milk programs. Responses were received from 414 students and the data was subjected to frequency analysis, t-test, and conjoint analysis using the SPSS Statistics Package. While evaluating white milk in the school milk program, middle school students rated ‘packaging condition’ (4.23) the highest, high school students rated ‘nutrition’ (4.64) the highest, and their evaluation of all the quality attributes was significantly different from that of middle school students (p<0.001). Overall satisfaction scores too, showed a significant difference between high school (4.46) and middle school students (4.01) (p<0.001). Processed milk & dairy products had the highest satisfaction score in the attribute of ‘serving time’ (4.57). The relative importance of the choice attributes of the school milk program was in the order of ‘number per item’ (62.260%), ‘temperature’ (25.708%), and ‘serving method’ (12.032%) for all students. The school milk program most preferred by all students and middle school students was to provide milk at a refrigerated temperature, select white milk three times a week, processed milk, fermented milk, and cheese twice a week, and provide it at the desired time.

This study was performed to investigate the effects of water molecules on ozone oxidation of acetaldehyde using a manganese oxide catalyst at room temperature. The catalytic ozone oxidation was conducted at different relative humidity (RH) conditions of 0%, 50%, and 80%. As the RH increased, both ozone and acetaldehyde removal efficiencies dropped due to competitive adsorption on the surface of the catalyst. At the highest RH of 80%, the oxidation reaction was severely retarded, and oxidation by-products such as acetic acid were formed and adsorbed on the surface. After the ozone oxidation of acetaldehyde, the regeneration of the catalyst using ozone alone was tested, and the further oxidation of accumulated organic compounds was investigated under the RH conditions of 0%, 50%, and 80%. When the highest relative humidity was introduced in the regeneration step, the ozonation reaction with the by-products adsorbed on the catalyst surface decreased due to the competitive reaction with water molecules. These findings revealed that, only when relative humidity was low to minimize the formation of by-products, the ozone oxidation of acetaldehyde using the manganese oxide catalyst at room temperature can be feasible as an effective control method.

해저 파이프라인 예비커미셔닝(Pre-commissioning) 단계는 입수(Flooding), 배수(Venting), 하이드로테스팅(Hydrotesting), 탈수 (Dewatering), 건조(Drying), 질소충진(N2 Purging)의 공정과정으로 구성된다. 이 중 건조와 질소충진 과정은 운용 중 파이프라인 내부에 하이 드레이트(Hydrate)의 발생과 가스 폭발의 위험을 방지하기 위해 상대습도를 이슬점 아래로 감소 및 유지되도록 규정되어 있다. 본 연구의 목적은 해저 파이프라인 예비커미셔닝 중, 공기건조(Air Drying)와 질소충진 공정과정에 대한 해석법을 개발하고 현장계측 결과와의 상호 비교를 통해 해석법의 활용가능성을 평가하는 데 있다. 해저 파이프라인 내부 상대습도 평가를 위한 방법으로 전산열유체(CFD)를 활용한 해석기법을 도입·적용하였고 해양공사 해저 파이프라인 공기건조와 질소충진 공정과정에 대한 현장계측 결과와 잘 일치함을 확인하였다. 개발된 공기건조와 질소충진 해석법 및 평가방법을 향후 해저 파이프라인 예비커미셔닝 작업의 사전 엔지니어링 도구로 활용할 경우, 작 업생산성 향상에 크게 기여할 것으로 사료된다.

본 연구는 다양한 상대습도(11~93%) 조건에서 해조류의 미생물 안정성 및 품질특성에 미치는 영향을 조사하였다. 미생물 안정성은 저장 중 대장균군, 일반세균, 효모 및 곰팡이수를 분석하였다. 일반세균은 상대습도 69~93%에서 4.40~7.00 log CFU/g, 효모 및 곰팡이는 4.20~6.40 log CFU/g로 상대습도 69%이상 조건에서 일반세균, 효모 및 곰팡이의 수가 급격하게 증가하였다. 고결현상은 상대습도 11~53% 조건에서는 일어나지 않았으나 69, 81, 93% 조건에서는 각각 86.9, 99.45, 99.98%로 높은 고결현상을 가지는 것으로 나타났다. 색도는 상대습도가 높아질수록 L값과 b값이 감소하였고, a값이 증가하여 갈변현상이 일어났다. 또한, 총 페놀함량(9.10~8.66 mg GAE/100 g dw), ABTS 소거능(24.20~24.18 mg AAE/100 g dw), FRAP(15.34~15.33 mg Fe(II)/100 g dw)활성은 저장 중 상대습도 11~33%에서 가장 높게 유지되었다. 그러나, 상대습도 43~93%에서 저장 중 총 페놀함량(8.66~4.00 mg GAE/100 g dw), ABTS(22.57~4.50 mg AAE/100 g dw), FRAP(13.06~4.00 mg AAE/100 g dw)활성이 감소하는 것으로 나타났다. 상대습도 81% 조건에서 ABTS 및 FRAP이 1/3배로 감소하였고, 93% 조건에서 총 페놀함량, ABTS 및 FRAP이 각각 1/2배, 1/5배, 1/3배로 감소하였다. 따라서, 일반세균, 효모 및 곰팡이의 성장 억제, 고결현상 방지, 갈변억제, 높은 총 페놀함량과 항산화활성 유지를 위해서는 상대습도 53% 이하의 조건에서 보관하는 것이 미생물 안정성 및 품질특성 유지에 효과적일 것으로 판단된다.