본 연구는 노후화된 교량의 단면 보수를 위한 고성능 콘크리트 보수재료를 개발하는 것을 목표로 하여 진행하였다. 건식 숏크리트 방법을 사용하여 최적의 혼합비를 도출하기 위해 재료에 대한 기본 실험을 바탕으로 내구성 및 수밀성 측면에서 적합한 성능을 개발 하기 위한 실험을 진행하였다. 본 연구는 실리카 흄, 고로슬래그, 자연섬유 등을 혼합하여 각 변수별 차이를 비교하였으며, 압축강도, 소성 수축, 염소 이온 침투 저항성, 동결융해 실험을 통해 성능을 평가하였다. 본 연구 결과 실리카 흄과 천연 섬유를 혼합하여 내구 성 및 수밀성을 확보한 채 팽창제와 폴리머 분말수지를 혼입하여 적합한 성능을 가진 보수재료를 개발하기 위한 기초 연구를 완료하 였다. 이 보수재료는 압축강도, 동결융해 저항성, 소성수축 균열 저감성, 염소 이온 침투 저항성 측면에서 우수한 성능을 보여줄 것이 다. 본 연구에서 개발될 보수재료는 기존 보수 모르타르보다 성능이 우수하며, 건식 숏크리트 방식을 사용하기 때문에 작업 및 후처리 과정이 습식 숏크리트 방식보다 간단하여 소구 작업에 더욱 효율적일 것으로 판단된다.

The concrete silo dry storage system, which has been in operation at the Wolsong NPP site since 1992, consists of a concrete structure, a steel liner plate in the inner space, and a fuel basket. The silo system’s concrete structure must maintain structural integrity as well as adequate radiation shielding performance against the high radioactivity of spent nuclear fuel stored inside the storage system. The concrete structure is directly exposed to the external climatic environment in the storage facility and can be expected to deteriorate over time owing to the heat of spent nuclear fuel, as well as particularly cracks in the concrete structure. These cracks may reduce the radiation shielding performance of the concrete structure, potentially exceeding the silo system’s allowable radiation dose rate limits. For specimens with the same composition and physical properties as silo’s concrete structures, cracks were forcibly generated and then irradiated to measure the change in radiation dose rate to examine the effect of cracks in concrete structures on radiation shielding performance, and in the current state, the silo system maintains radiation shielding performance.

Interim dry cask storage systems comprising AISI 304 or 316 stainless steel canisters have become critical for the storage of spent nuclear fuel from light water reactors in the Republic of Korea. However, the combination of microstructural sensitization, residual tensile stress, and corrosive environments can induce chloride-induced stress corrosion cracking (CISCC) for stainless steel canisters. Suppressing one or more of these three variables can effectively mitigate CISCC initiation or propagation. Surface-modification technologies, such as surface peening and burnishing, focus on relieving residual tensile stress by introducing compressive stress to near-surface regions of materials. Overlay coating methods such as cold spray can serve as a barrier between the environment and the canister, while also inducing compressive stress similar to surface peening. This approach can both mitigate CISCC initiation and facilitate CISCC repair. Surface-painting methods can also be used to isolate materials from external corrosive environments. However, environmental variables, such as relative humidity, composition of surface deposits, and pH can affect the CISCC behavior. Therefore, in addition to research on surface modification and coating technologies, site-specific environmental investigations of various nuclear power plants are required.

목적 : 일개 대학 안경광학과 대학생들의 지각된 스트레스, 주관적 건강상태, 안구건조 및 구강건조 증상의 관련 성을 알아보고자 한다. 방법 : 일개 대학 안경광학과 대학생 150명을 대상으로 일반적 특성 8문항, 스트레스 자각적도 10문항, 안구건 조 증상 8문항, 구강건조 증상 6문항을 온라인으로 설문 조사하였다. 통계분석은 독립표본 t-검정과 ANOVA 분 석, pearson의 상관분석, 회귀분석을 실시하였다. 결과 : 여학생이 남학생보다 지각된 스트레스와 안구건조 증상이 더 높았으며, 스마트폰 사용 시간이 7시간 이 상일 때 안구건조 증상이 유의하게 증가하는 것으로 나타났다. 또한, 음주자가 비음주자보다 낮은 스트레스를 지각 했으며, 안구건조와 구강건조 증상은 지각된 스트레스와 정적 상관관계를 보였다. 주관적 건강상태는 스트레스와 부적 상관관계를 나타냈으며, 특히 주관적 구강건강 상태가 나쁜 그룹은 스트레스 수준이 더 높았다. 결론 : 본 연구 결과는 지각된 스트레스가 안구건조 및 구강건조 증상과 관련이 있음을 시사하며, 학생들의 스 트레스 관리 및 건강상태 모니터링의 필요성을 강조한다. 추후 연구에서는 다양한 연령대와 스트레스 요인을 포함 한 연구가 필요할 것이다.

This study was carried out to investigate the effects of seeding dates on the growth characteristics, dry matter yield and mineral contents of rye cultivated in the paddy field. The field experiment was conceived as a randomized block design performed in triplicate with seeding dates of October 19 (T1), October (T2), November 2 (T3), November 9 (T4), and November 16 (T5). All treatments was harvested on May 22 of the following year. Plant length, stem diameter, dry matter yield, and total digestible nutrient (TDN) yield were higher in rye with early seeding dates (p<0.05), whereas TDN was higher with late seeding dates (p<0.05). There was no significant difference between crude protein and ether extract among the different seeding dates. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were higher with early seeding dates (p<0.05). K and Ca contents were significantly higher at T1 as compared to other treatments (T2, T3, T4 and T5). There was no significant difference in Mg and Na content among T1, T2, T3, T4 and T5 treatments. P content was higher in the order T1 > T2 > T3 > T4 > T5 (p<0.05). There was no significant difference in free sugar contents (glucose, fructose and sucrose) by treatments, whereas total free sugar content was the highest in T1 than in the other treatments (p<0.05). Collectively, the results obtained in this study indicate that it is favorable to seed (T1 and T2) soon after harvesting rice to increase dry matter, TDN yield and total free sugar content of rye in the midlands of Korea.

식품공전 시험법은 식품기초규격 적부 판정, 수거검사의 적부판정, 수입식품의 적부판정 등의 판단근거가 되기 때문 에 식품산업에서 매우 중요하다. 본 연구는 도시락, 밀키트, 된장에 오염된 일반세균, 대장균군, 효모, 곰팡이, 대장균을 분리하기 방법으로 사용되는 평판배지법, Petrifilm법, Compact Dry법을 이용해 각각의 세균을 분리하였고, 회수율을 비교 하였다. 식품 내 자연균총(일반세균, 효모/곰팡이, 대장균군) 검출은 평판배지 PCA, PDA, DCLA와 Petrifilm AC, YM, CC의 성능을 Compact Dry TC, YMR, CF와 비교하였다. 인 위접종한 대장균(E. coli)의 경우는 평판배지 EMB, Petrilfilm EC, Compact Dry EC의 검출능을 비교하였다. 본 실험결과, 일반세균, 대장균군, 대장균의 검출에서 Compact Dry법은 기 존의 평판배지법 및 건조배지법과 비교하여 식품 내 각각의 세균수를 계수하는데 유의적 차이를 보이지 않았다(P>0.05). 또한, 평판배지법과 Compact Dry간의 상관관계 및 Petrifilm 과 Compact Dry간의 상관관계 역시 1에 가까운 높은 값을 확인하였다. Compact Dry법은 미생물 분석을 위해 배지 준 비 과정이 필요 없으며, 접종 후 자체 확산이 가능하여 사 용하기 쉽고, 공간을 효율적으로 사용할 수 있으므로 기존 의 배지를 사용하는 방법에 비해 많은 장점을 제공하였다. 따라서 식품 중 일반세균, 대장균군, 대장균의 검출을 위한 Compact Dry법(Compact Dry TC, CF, EC)은 기존의 식품공 전 상 등재된 다른 건조필름법을 대체 가능한 것으로 판단된다.

The 300 concrete silo systems installed and operated at the site of Wolsong nuclear power plant (NPP) have been storing CANDU spent nuclear fuel (SNF) under dry conditions since 1992. The dry storage system must be operated safely until SNF is delivered to an interim storage facility or final repository located outside the NPP in accordance with the SNF management policy of the country. The silo dry storage system consists of a concrete structure, liner steel plate in the inner cavity, and fuel basket. Because the components of the silo system are exposed to high energy radiation owing to the high radioactivity of SNF inside, the effects of irradiation during long-term storage must be analyzed. To this end, material specimens of each component were manufactured and subjected to irradiation and strength tests, and mechanical characteristics before and after irradiation were examined. Notably, the mechanical characteristics of the main components of the silo system were affected by irradiation during the storage of spent fuel. The test results will be used to evaluate the long-term behavior of silo systems in the future.

The objective of this study was to compare the feeding effects of imported timothy hay, domestic Italian ryegrass silage (IRGS) and IRG dried by hot-air dry system (IRGHDS) under basic total mixed ration (bTMR) on rumination activity, milk production, and milk composition in lactating dairy cows. Eighteen Holstein dairy cows were divided into three groups: control (bTMR + imported timothy hay), treatment 1 (bTMR + IRGS) and treatment 2 (TMR + IRGHDS) groups. The study was conducted over a total period of 24 days, including a 10 days adaptation period and a 14 days main experimental period. The results indicate body weight was not significantly different between the three groups (p>0.05), and rumination time was significantly higher in the treatment 1 group compared with the control group (p<0.001). Milk fat, protein, and lactose were not significantly different between the three groups (p>0.05), however, somatic cell counts were significantly lower in the treatment 1 group compared with the control group (p<0.001). As a result of the economic feasibility analysis, it is expected that feeding TMR using IRGS and IRGHDS will increase profit by 402.8 won/day and 331.4 won/day per cow compared to imported timothy hay. Therefore, IRGS and IRGHDS can be used as substitutes for imported timothy hay in feeding lactating dairy cows.

This study performed the pre-treatments of the manufacturing of the pork skin snack with wet-salting (3% and 6%; 3W and 6W) and dry-salting (0.3% and 0.6%; 0.3D and 0.6D). Regarding the manufacturing yield, the 0.3D and 6W were significantly higher than the other samples (p<0.05). The water contents of the Con and 0.6D were significantly lower than the other samples (p<0.05). The fat contents of the Con and 6W were evidently higher than the 3W, 0.3D, and 0.6D (p<0.05). The lightness of the wet-salting group was markedly higher than the Con (p<0.05). The redness and yellowness of the 0.6D were noticeably higher than the Con (p<0.05). The crispness of the 0.6D was considerably higher than the other samples (p<0.05). The appearance and sensory crispness of the 3W and 0.6D were notably lower than the other samples (p<0.05). The taste score of the 0.6D was much lower than the 6W and 0.3D (p<0.05). The overall acceptability of the Con, 6W, and 0.3D was appreciably higher than the other samples (p<0.05). Overall, this study showed that wet-salting with 6% (6W) and dry-salting with 0.3% (0.3D) can improve pork skin snack quality properties.