Nasopharyngeal stenosis is defined as a morphological transition of narrowing at the nasopharyngeal region. A 2-yearold, castrated male, Korean short hair cat was referred to the animal medical center, Gyeongsang National University. According to clinical signs, diagnostic imaging, and physical examination, nasopharyngeal stenosis was diagnosed. The staphylectomy was performed using a CO2 laser, and there were not any post-operative complications. The patient was discharged in two days. This report describes the case of nasopharyngeal stenosis in cat and represents that laser ablation could be a good option for surgical management of the nasopharyngeal region with a low complication rate.

The domestic Pressurized Heavy Water Reactor (PWHR) nuclear power plant, Wolsong Unit 1, was permanently shut down on December 24, 2019. However, research on decommissioning has mainly focused on Pressurized Water Reactors (PWRs), with a notable absence of both domestic and international experience in the decommissioning of PHWRs. If proper business management such as radiation safety and waste is not performed, it can lead to increased business risks and costs in decommissioning. Therefore, the assessment of waste volume and cost, which provide fundamental data for the nuclear decommissioning process, is a crucial technical requirement before initiating the actual decommissioning of Wolsong Unit 1. Decommissioning radiation-contaminated structures and facilities presents significant challenges due to high radiation levels, making it difficult for workers to access these areas. Therefore, technology development should precede decommissioning process assessments and safety evaluations, facilitating the derivation of optimal decommissioning procedures and ensuring worker safety while enhancing the efficiency of decommissioning operations. In this study, we have developed a program to estimate decommissioning waste amounts for PHWRs, building upon prior research on PWR decommissioning projects while accounting for the specific design characteristics of PHWRs. To evaluate the amount of radioactive waste generated during decommissioning, we considered the characteristics of radioactive waste, disposal methods, packaging container specifications, and the criteria for the transfer of radioactive waste to disposal operators. Based on the derived algorithm, we conducted a detailed design and implemented the program. The proposed program is based on 3D modeling of the decommissioning components and the calculation of the Work Difficulty Factor (WDF), which is used to determine the time weighting factors for each task. Program users can select the cutting and packaging conditions for decommissioning components, estimate waste amount based on the chosen decommissioning method, and calculate costs using time weighting factors. It can be applied not only to PHWRs, but also to PWRs and non-nuclear fields, providing a flexible tool for optimizing decommissioning process.

Decommissioning waste is generated with various types and large quantities within a short period. Concrete, a significant building material for nuclear facilities, is one of the largest decommissioning wastes, which is mixed with aggregate, sand, and cement with water by the relevant mixing ratio. Recently, the proposed treatment method for volume reduction of radioactive concrete waste was proven up to scale-up testing using unit equipment, which involved sequentially thermomechanical and chemical treatment. According to studies, the aggregate as non-radioactive material is separated from cement components with contaminated radionuclides as less than clearance criteria, so the volume of radioactive concrete waste is decreased effectively. However, some supplementation points were presented to commercialize the process. Hence, the process requires efficiency as possible to minimize the interface parts, either by integration or rearranging the equipment. In this study, feasibility testing was performed using integrated heating and grinding equipment, to supplement the possible issue of generated powder and dust during the process. Previously, heat treatment and grinding devices were configured separately for pilot-scale testing. But some problems such as leakage and pipe blockage occurred during the transportation of generated fine powder, which caused difficulties in maintaining the equipment. For that reason, we studied to reduce the interface between the equipment by integrating and rearranging the equipment. To evaluate the thermal grinding performance, the fraction of coarse and concrete fines based on 1mm particle size was measured, and the amount of residual cement in each part was analyzed by wet analysis using 4M hydrochloric acid. The result was compared with previous studies and the thermomechanical equipment could be selected to enhance the process. Therefore, it is expected that the equipment for commercialization could be optimized and composed the process compactly by this study.

With the aging of nuclear power plants (NPPs) in 37 countries around the world, 207 out of 437 NPPs have been permanently shutdown as of August 2022 according to the IAEA. In Korea, the decommissioning of NPPs is emerging as a challenge due to the permanent shutdown of Kori Unit 1 and Wolsong Unit 1. However, there are no cases of decommissioning activities for Heavy Water Reactor (HWR) such as Wolsong Unit 1 although most of the decommissioning technologies for Light Water Reactor (LWR) such as Kori Unit 1 have been developed and there are cases of overseas decommissioning activities. This study shows the development of a decommissioning waste amount/cost/process linkage program for decommissioning Pressurized Heavy Water Reactor (PHWR), i.e. CANDU NPPs. The proposed program is an integrated management program that can derive optimal processes from an economic and safety perspective when decommissioning PHWR based on 3D modeling of the structures and digital mock-up system that links the characteristic data of PHWR, equipment and construction methods. This program can be used to simulate the nuclear decommissioning activities in a virtual space in three dimensions, and to evaluate the decommissioning operation characteristics, waste amount, cost, and exposure dose to worker. In order to verify the results, our methods for calculating optimal decommissioning quantity, which are closely related to radiological impact on workers and cost reduction during decommissioning, were compared with the methods of the foreign specialized institution (NAGRA). The optimal decommissioning quantity can be calculated by classifying the radioactivity level through MCNP modeling of waste, investigating domestic disposal containers, and selecting cutting sizes, so that costs can be reduced according to the final disposal waste reduction. As the target waste to be decommissioning for comparative study with NAGRA, the calandria in PHWR was modeled using MCNP. For packaging waste container, NAGRA selected three (P2A, P3, MOSAIK), and we selected two (P2A, P3) and compared them. It is intended to develop an integrated management program to derive the optimal process for decommissioning PHWR by linking the optimal decommissioning quantity calculation methodology with the detailed studies on exposure dose to worker, decommissioning order, difficulty of work, and cost evaluation. As a result, it is considered that it can be used not only for PHWR but also for other types of NPPs decommissioning in the future to derive optimal results such as worker safety and cost reduction.

Samples were collected between August 2016 and May 2017 at Sangju-si, Gyeongsangbuk- do, Jeju-do, and Uljin-gun, Gangwon-do. As a result, one genus and six species were newly recorded in Korea. The unrecorded indigenous genus was Borzia, and the six species were Anagnostidinema acutissimum, Komvophoron bourrellyi, Hydrocoleum stankovicii, Borzia trilocularis, Phormidium tinctorium and Pseudanabaena lohchoides. Phormidium tinctorium and Pseudanabaena lohchoides had been reported to inhabit freshwater, but in this study, these were found in brackish water. It had also been reported that B. trilocularis trichomes are composed of up to 8 cells, but in this study, a maximum of 10 cells was observed.

We analyze the spiral structure of 1725 nearby spiral galaxies with redshift less than 0.02. We use the color images provided by the Sloan Digital Sky Survey. We determine the arm classes (grand design, multiple-arm, flocculent) and the broad Hubble types (early, intermediate, late) as well as the bar types (SA, SAB, SB) by visual inspection. We find that flocculent galaxies are mostly of late Hubble type while multiple-arm galaxies are likely to be of early Hubble type. The fractional distribution of grand design galaxies is nearly constant along the Hubble type. The dependence of arm class on bar type is not as strong as that of the Hubble type. However, there is about a three times larger fraction of grand design spirals in SB galaxies than in SA galaxies, with nearly constant fractions of multiple-arm galaxies. However, if we consider the Hubble type and bar type together, grand design spirals are more frequent in early types than in late types for SA and SAB galaxies, while they are almost constant along the Hubble type for SB galaxies. There are clear correlations between spiral structures and the local background density: strongly barred, early-type, grand design spirals favor high-density regions, while non-barred, late-type, flocculent galaxies are likely to be found in low-density regions.