Korea has signed nuclear cooperation agreements (NCA) with 29 countries. Nuclear materials, materials, equipment, and technology transferred under the agreements are “internationally controlled materials (ICM)” under the Nuclear Safety Act. The main obligations imposed on those items include ensuring peaceful use, safeguards, physical protection, annual inventory reporting, and retransfer with supplier prior consent. The Nuclear Export and Import Control System (NEPS) handles the export control procedures for transferring ICM. After import, inventory management for ICM in Korea would be transitioning to an item-based system through the Obligation Tracking System for internationally controlled item (OTS) currently under development. A one-stop import and export control system for ICM can be established when information is well-linked between these two systems. This paper aims to derive a methodology for integrating NEPS and OTS. NEPS-OTS coupling begins at the receipt confirmation and shipment notification stages in NEPS. When importing ICM under NCA, the inventory change (code RF: receipt foreign) is entered in OTS by getting the information that has completed the receipt confirmation in NEPS. Conversely, during export, the information that has completed the shipment notification procedure in NEPS is linked to the OTS so that the entire cycle from import to re-export of the ICM can be concluded. Inventory verification for retransfer, checking that the book inventory remains positive value, is impossible under the current system. This issue can be resolved by enabling inventory information in OTS to be displayed in NEPS. Determining when and how to generate the obligation code for imported ICM is essential for NEPS-OTS coupling. Manual input may be necessary for some cases with multiple obligations. Nevertheless, it is more efficient from a system communication protocol to automatically generate and impose a single obligation based on the supplier country information in NEPS. Moreover, it is important to automatically link crucial information available in NEPS to reduce the administrative burden on OTS users and discrepancies between systems. Most required OTS data, such as country obligation, item categories, quantity, physical or chemical form, and receipt date, can be directly linked from NEPS. However, NEPS improvement is needed for digitizing the receiver information and facility data, like the material balance area. The NEPS-OTS integration involves sharing data as a system and encompasses the connection between export control and inventory management. Future work to link some information in NEPS -OTS with the KSIS could be suggested to enhance efficiency and effectiveness in managing ICM.

The ROK government has developed the Nuclear Export and Control System (NEPS) to implement export control activities. Although it was launched in 2008 as a system that can work with classification, licensing, nuclear material approval, government-to-government assurance, complying with nuclear cooperation agreement (NCA) handled through official documents. In order to enhance systematic management for items subject to NCA, KINAC developed a new module for the procedure (hereinafter referred to as “NCA module”) and opened it in 2022. This paper presents the module’s development background, key features, and current operation status. The NCA module prioritizes functional expansion and flexibility, distinct from other tasks for the following reasons. First, the export control duties of classification, export license, and approval for NM are based on domestic law, leading to predetermined target items, application forms, and processes that change only through statutory amendments. In contrast, the implementation of NCA has numerous procedural variables, varying across countries in scope, content, and procedures. Therefore, if the function is over-standardized, there would be many exceptions that the system cannot resolve in practice. Second, the existing NEPS process entails a one-time decision or approval for each application, while the implementation of the agreement encompasses four related procedures for each item: prior notification, written confirmation, shipment notification, and receipt confirmation. Even some steps may be omitted depending on the case. The other difference is the working process. The implementation of NCA must be initiated from the government, so the existing methods, beginning with the licensee filling a form, cannot be adopted as it is. The NCA module has adopted a new reference numbering system to resolve these challenges. It enables the creation of multiple procedures under one reference number on an item to expand the tasks and make it possible to omit some steps or to reflect case-by-case concerns in each stage. It also provides a consolidated view of multiple notifications related to a single item, ensuring to deal with even long-running tasks without missing any obligations until the final procedure. Moreover, some of the data in the NCA module is extensible by allowing users to manage the list themselves. For example, the system can respond to new agreements by allowing users to add and modify codes that distinguish counterparty countries. As a result, the current NCA module accommodates a variety of implementation scenarios, including split shipments, the procedural omissions, and the modification of additional counterparties, offering enhanced flexibility and adaptability.

We investigate 20 post-coronal mass ejection (CME) blobs formed in the post-CME current sheet (CS) that were observed by K-Cor on 2017 September 10. By visual inspection of the trajectories and projected speed variations of each blob, we nd that all blobs except one show irregular \zigzag" trajectories resembling transverse oscillatory motions along the CS, and have at least one oscillatory pattern in their instantaneous radial speeds. Their oscillation periods are ranging from 30 to 91 s and their speed amplitudes from 128 to 902 kms􀀀1. Among 19 blobs, 10 blobs have experienced at least two cycles of radial speed oscillations with dierent speed amplitudes and periods, while 9 blobs undergo one oscillation cycle. To examine whether or not the apparent speed oscillations can be explained by vortex shedding, we estimate the quantitative parameter of vortex shedding, the Strouhal number, by using the observed lateral widths, linear speeds, and oscillation periods of the blobs. We then compare our estimates with theoretical and experimental results from MHD simulations and uid dynamic experiments. We nd that the observed Strouhal numbers range from 0.2 to 2.1, consistent with those (0.15{3.0) from uid dynamic experiments of blu spheres, while they are higher than those (0.15{0.25) from MHD simulations of cylindrical shapes. We thus nd that blobs formed in a post-CME CS undergo kinematic oscillations caused by uid dynamic vortex shedding. The vortex shedding is driven by the interaction of the outward-moving blob having a blu spherical shape with the background plasma in the post-CME CS.

The Korea Astronomy and Space Science Institute (KASI) has been developing a next-generation coronagraph (NGC) in cooperation with NASA to measure the coronal electron density, temperature, and speed simultaneously, using four different optical filters around 400 nm. KASI organized an expedition to demonstrate the coronagraph measurement scheme and the instrumental technology during the 2017 total solar eclipse (TSE) across the USA. The observation site was in Jackson Hole, Wyoming, USA. We built an eclipse observation system, the Diagnostic Coronal Experiment (DICE), composed of two identical telescopes to improve the signal-to-noise ratio. The observation was conducted at four wavelengths and three linear polarization directions in the limited total eclipse time of about 140 seconds. We successfully obtained polarization data for the corona but we were not able to obtain information on the coronal electron temperature and speed due to the low signal-to-noise ratio of the optical system and strong emission from prominences located at the western limb. In this study, we report the development of DICE and the observation results from the eclipse expedition. TSE observation and analysis with our self-developed instrument showed that a coronagraph needs to be designed carefully to achieve its scientific purpose. We gained valuable experience for future follow-up NASA-KASI joint missions: the Balloon-borne Investigation of the Temperature and Speed of Electrons in the Corona (BITSE) and the COronal Diagnostic EXperiment (CODEX).

A coelostat is often used for solar observations, because it corrects the image rotation auto- matically by guiding sunlight into a fixed telescope with two plane mirrors. For the purposes of education and spectroscopic observation, the solar group at Seoul National University (SNU) plans to develop the SNU coelostat (SNUC) and install it in the SNU Astronomical Observatory (SAO). Requirements of the SNUC are < 1′′ positioning accuracy with 30 cm beam size on the entrance pupil in the compact dome. To allow for installation in the small dome, we design a compact slope type coelostat with a 45 cm primary plane mirror and a 39 cm secondary plane mirror. The motion of the SNUC is minimized by fixing the position of the slope frame. Numerical simulations of the available observational time of the designed coelostat shows that the sun can be observed ay all times from June to early August and at least three hours in other months. Since the high accuracy driving motors installed in the SNUC can be affected by external environment factors such as humidity and temperature variations, we design a prototype to test the significance of these effects. The prototype consists of a 20 cm primary plane mirror, a 1 m slope rail, a direct drive motor, a ballscrew, a linear motion guide, an AC servo motor, a reduction gear and a linear encoder. We plan to control and test the accuracy of the prototype with varying atmospheric conditions in early 2019. After testing the prototype, the SNUC will be manufactured and installed in SAO by 2020.

In a solar coronagraph, the most important component is an occulter to block the direct light from the disk of the sun. Because the intensity of the solar outer corona is 10−6 to 10−10 times of that of the solar disk (I⊙), it is necessary to minimize scattering at the optical elements and diffraction at the occulter. Using a Fourier optic simulation and a stray light test, we investigated the performance of a compact coronagraph that uses an external truncated-cone occulter without an internal occulter and Lyot stop. In the simulation, the diffracted light was minimized to the order of 7.6 × 10−10 I⊙ when the cone angle c was about 0.39◦. The performance of the cone occulter was then tested by experiment. The level of the diffracted light reached the order of 6 × 10−9 I⊙ at c = 0.40◦. This is sufficient to observe the outer corona without additional optical elements such as a Lyot stop or inner occulter. We also found the manufacturing tolerance of the cone angle to be 0.05◦, the lateral alignment tolerance was 45 μm, and the angular alignment tolerance was 0.043◦. Our results suggest that the physical size of coronagraphs can be shortened significantly by using a cone occulter.