In this study, NASICON-type Li1+XGaXTi2-X(PO4)3 (x = 0.1, 0.3 and 0.4) solid-state electrolytes for all-solid-state batteries were synthesized through the sol-gel method. In addition, the influence on the ion conductivity of solid-state electrolytes when partially substituted for Ti4+ (0.61Å) site to Ga3+ (0.62Å) of trivalent cations was investigated. The obtained precursor was heat treated at 450 °C, and a single crystalline phase of Li1+XGaXTi2-X(PO4)3 systems was obtained at a calcination temperature above 650 °C. Additionally, the calcinated powders were pelletized and sintered at temperatures from 800 °C to 1,000 °C at 100 °C intervals. The synthesized powder and sintered bodies of Li1+XGaXTi2-X(PO4)3 were characterized using TGDTA, XRD, XPS and FE-SEM. The ionic conduction properties as solid-state electrolytes were investigated by AC impedance. As a result, Li1+XGaXTi2-X(PO4)3 was successfully produced in all cases. However, a GaPO4 impurity was formed due to the high sintering temperatures and high Ga content. The crystallinity of Li1+XGaXTi2-X(PO4)3 increased with the sintering temperature as evidenced by FE-SEM observations, which demonstrated that the edges of the larger cube-shaped grains become sharper with increases in the sintering temperature. In samples with high sintering temperatures at 1,000 °C and high Ga content above 0.3, coarsening of grains occurred. This resulted in the formation of many grain boundaries, leading to low sinterability. These two factors, the impurity and grain boundary, have an enormous impact on the properties of Li1+XGaXTi2-X(PO4)3. The Li1.3Ga0.3 Ti1.7(PO4)3 pellet sintered at 900 °C was denser than those sintered at other conditions, showing the highest total ion conductivity of 7.66 × 10-5 S/cm at room temperature. The total activation energy of Li-ion transport for the Li1.3Ga0.3Ti1.7(PO4)3 solidstate electrolyte was estimated to be as low as 0.36 eV. Although the Li1+XGaXTi2-X(PO4)3 sintered at 1,000 °C had a relatively high apparent density, it had less total ionic conductivity due to an increase in the grain-boundary resistance with coarse grains.
We introduce a method for preserving yellow mealwom (Tenebrio molitor) larvae for an extended period and show that a high percentage of larvae can survive in good health under low-temperature storage conditions combined with specific diapause termination conditions. When storing larvae for 140 days, the storage temperature can be varied based on our goals, giving us control over yellow mealworm production to meet specific demands. To produce adult beetles, storing larvae at 15 ℃ with wheat bran and ending diapause at 30 ℃ resulted in 90% pupation rate, with 60% becoming adults in 21 days. If our aim is larvae production, storing them at 10–12 ℃ with wheat bran and ending diapause at 25–30 ℃ allows the larvae to reach a suitable weight for processing. This approach ensures long-term storage of yellow mealworm larvae and provides a practical way to control their development, allowing efficient mass production tailored to market demands.
천궁(Cnidium officinale Makino, COM)은 산형과(Umbelliferae)에 속하는 산림약용자원 중 하나로 뿌리나 지하 부를 건조한 후 약용으로 사용하는 여러해살이 산림약초 중 하나이다. 천궁(COM)은 고혈압, 진통 및 진정 등에 효과가 있다고 알려져 있어, 산림약용자원으로서 재배되는 품목 중 하나이지만 해충의 피해가 심각하여 방제에 어려움이 많이 있다. 천궁은 뿌리가 약재로 사용되지만 종근에 피해를 가하는 응애류 및 파리류 해충은 지하부에 활동하는 생태특성을 가지고 있어 피해초기에 발견하기 어려울 뿐만 아니라 방제가 어려운 실정이다. 천궁 (COM)은 연작이 되지 않은 작물 중에 하나이므로 재배포장을 매년 바꿔가면서 재배되고 있는 실정이다. 수확시 기는 가을이므로 재배하는 동안에는 정확한 병해충조사가 쉽지 않을 뿐만 아니라 정확한 발생시기 및 피해정도 를 확인하는 것이 어려운 실정이다. 본 연구의 목적은 천궁의 해충 및 천적곤충에 대해 조사하여 천궁의 해충종류 및 발생에 대해 이해하고 이를 기반으로 친환경 방제를 위한 천적류의 정보수집 및 분석 등을 위한 기초자료로 제공하고자 한다.
After the major radioactivation structures (RPV, Core, SG, etc.) due to neutron irradiation from the nuclear fuel in the reactor are permanently shut down, numerous nuclides that emit alpha-rays, beta-rays, gamma-rays, etc. exist within the radioactive structures. In this study, nuclides were selected to evaluate the source term for worker exposure management (external exposure) at the time of decommissioning. The selection of nuclides was derived by sequentially considering the four steps. In the first stage, the classification of isotopes of major nuclides generated from the radiation of fission products, neutron-radiated products, coolant-induced corrosion products, and other impurities was considered as a step to select evaluation nuclides in major primary system structures. As a second step, in order to select the major radionuclides to be considered at the time of decommissioning, it is necessary to select the nuclides considering their half-life. Considering this, nuclides that were less than 5 years after permanent suspension were excluded. As a third step, since the purpose of reducing worker exposure during decommissioning is significant, nuclides that emit gamma rays when decaying were selected. As a final step, it is a material made by radiation from the fuel rod of the reactor and is often a fission product found in the event of a Severe accident at a nuclear power plant, and is excluded from the nuclide for evaluation at the time of decommissioning is excluded. The final selected Co-60 is a nuclide that emits high-energy gamma rays and was classified as a major nuclide that affects the reduction of radiation exposure to decommissioning workers. In the future, based on the nuclide selection results derived from this study, we plan to study the evaluation of worker radiation exposure from crud to decommissioning workers by deriving evaluation results of crud and radioactive source terms within the reactor core.
Zinc injection into the coolant system of nuclear power plants is an effective method for reducing corrosion and improving performance. The effectiveness of this method is influenced by various factors such as zinc concentration and injection rate. This paper provides an overview of the factors affecting the effectiveness of zinc injection in nuclear power plants, with a focus on zinc concentration and injection rate, and discusses various research results on the effects of these factors on corrosion reduction and coolant system performance. Zinc concentration is an important factor affecting the effectiveness of zinc injection. The research results show that gradual increases in zinc concentration are more effective for coolant system stability. However, the concentration should not exceed the recommended levels as high zinc concentrations can have negative effects on the system. Injection rate is also an important factor affecting the effectiveness of this method. The research results show that gradual increases in injection rate are more effective for coolant system stability. However, excessive injection rates can have negative effects on the system such as overload of the zinc injection facility and chemical shocks within the coolant system, and therefore, should be optimized. In conclusion, zinc concentration and injection rate are important factors affecting the effectiveness of zinc injection in nuclear power plants. The optimal concentration and injection rate should be determined based on specific reactor conditions and system requirements, and efforts should be made to maximize corrosion reduction and performance improvement.
Korean innovative SMR has been implemented developing with improved safety/economy and i- SMR technology development project to secure a competitive edge in SMR. For nuclear power plants, according to the revision of the Nuclear Safety Act (2013.6), it is mandatory to be reflected in the aging management program of nuclear power plants, and the aging management and regulation of major nuclear power plants are being strengthened. For i-SMR, chemistry environment and management strategy is essential to mitigate corrosion and radiation fields, since it has compacted and integrated module designs. Since 1994, zinc injection into the reactor coolant system (RCS) has been applied more than 100 PWRs in the world to mitigate primary water stress corrosion cracking (PWSCC) and to reduce outof- core radiation fields. In domestic NPPs, 7 have been applying zinc injection and had up to 90% radiation field reductions. For this reason, SMR needs to apply zinc injection for chemistry strategy. Zinc target concentration will be 5~40 ppb at i-SMR, based on Ni-Fe-Cr materials as same as PWRs. Zinc injection location is in volume and purification control system between the volume control tank and charging P/P where the pressure is moderate. Zinc injection skid can consist of two micro-controllable pump (one for operation and one for stand-by) and one injection tank (batching tank for zinc solution). Zn, Ni, Si, Fe, and activated corrosion products should be monitored to identify zinc injection controls and trends. Flux mapping for core performance monitoring should be evaluated. The application of zinc will be essential and effective and bring sustainable reliability for corrosion control and mitigation strategy to meet the risk-free i-SMR development.
Ms. Hee Choon Oh was a Jeju Haenyeo(woman diver) and one of the few surviving victims of the Jeju 4.3 (1948). As a Haenyeo: Jeju society was very poor at the time during the Japanese colonial period and the division of the two Korea, especially after the Korean War, so she had to work regardless of gender. It was hard to go into the sea, but it was the only thing to support my family. In retrospect, Going out to work in the sea was like a life-threatening adventure every day. While there were many emergency moments, She becomes one with the sea and forgot all the pain. After having spent a lot of time together with the sea, I had to stop working as a Haenyeo because it was hard to take care of nine children after having heart surgery. I was able to receive Honorary Haenyeo through continuous exchanges and dedication to the society. As a victim of the Jeju 4.3: I had no choice but to explain it why I had to do work as a Haenyeo and to understand my life. I am a woman who chose the job of Haenyeo, but I have lived through the pain of the dark modern and contemporary history of Korea. The unfair one-year prison life that I wanted to hide even from my children hurt me all my life. Over the past 70 years, sharing pain with the sea, neighbors, and family, serving the region, and hopefully waiting for a better society and justice to come. and finally It was not until 2019, 70 years after 1948, that I was officially acquitted by a Korean court. I regained my honor as a Haenyeo and was able to get rid of my deep sadness.