Minuartia laricina (L.) Mattf. is a Korean native plant with high potential as a commercial flowering potted plant due to its compactness and long flowering duration. However, because this plant is a groundcover, it is susceptible to lodging and leggy growth. Therefore, this study investigated the effects of plant growth retardants (PGRs) on the inhibition of stem elongation and flowering characteristics of M. laricina. Commercial products, Trimmit, Cycocel, and B-Nine, were used for the exogenous PGR application of paclobutrazol (PBZ), chlormequat chloride (CCC), and daminozide (DMZ), respectively. Application concentrations were 50 and 100 mg·L-1 for PBZ; 100, 500, and 1,000 mg･L-1 for CCC; and 500, 1,000, and 2,000 mg·L-1 for DMZ. Paclobutrazol was the only PGR that inhibited stem elongation. The stem lengths of the plants treated with 50 or 100 mg·L-1 PBZ were 2.2 cm (13%) or 9.8 cm (57%) shorter, respectively, than those of the control. 50 mg·L-1 PBZ retarded stem growth effectively without negatively affecting flowering or other growth parameters, whereas 100 mg·L-1 PBZ caused excessive dwarfing and significantly reduced flowering by 59%. CCC and DMZ applications were ineffective for growth control. Flowering time was accelerated with most PGRs, except for 2,000 mg·L-1 DMZ, reducing the time to flowering by 2–8 days. These results indicate that the stem growth of M. laricina was successfully inhibited with PBZ but not with CCC or DMZ. Thus, we concluded that a single application of 50 mg·L-1 PBZ or similar treatment is effective in miniaturizing M. laricina without causing harm to its growth or aesthetic value, such as the flower number. Additionally, because CCC and DMZ are not persistent in the growing medium, testing multiple application times for these PGRs is crucial.

Under anoxic conditions, this study investigated removal of dissolved As(III) by Si and Al oxides including natural sand, chemically washed sand (silica), alumina, and activated alumina. Despite the similar surface area, natural sand showed greater extents of As(III) sorption than chemically washed sand. This was likely due to the high reactivity of Fe(oxyhydr)oxide impurities on the surface of natural sand. For both sands, As(III) sorption was the greatest at pH 7.1, in agreement with the weakly dissociating tendency of arsenous acid. Also, the least sorption was observed at pH 9.6. At basic pH, elevated silicate, which originated from the dissolution of silica in sands, would compete with As(III) for sorption. Due to the highest surface area, activated alumina was found to quantitatively immobilize the initially added As(III) (6.0×10−7 -2.0×10−5 M). Alumina showed As(III) sorption compared to or greater than chemically washed sand, although the former had less than 6% of the surface of area the latter. The greater reactivity of alumina than chemically washed sand can be explained by using the shared charge of oxygen.

This study explored the possibility of forming a coating layer containing alginic acid on the surface of a magnesium alloy to be used as a biomaterial. We formed a coating layer on the surface of a magnesium alloy using a plasma electrolytic oxidation process in an electrolytic solution with different amounts of alginic acid (0 g/L ~ 8 g/L). The surface morphology of all samples was observed, and craters and nodules typical of the PEO process were formed. The cross-sectional shape of the samples confirmed that the thickness of the coating layer became thicker as the alginic acid concentration increased. It was confirmed that the thickness and hardness of the sample significantly increase with increasing alginic acid concentration. The porosity of the surface and cross section tended to decrease as the alginic acid concentration increased. The XRD patterns of all samples revealed the formation of MgO, Mg2SiO4, and MgF2 complex phases. Polarization tests were conducted in a Stimulate Body Fluid solution similar to the body's plasma. We found that a high amount of alginic acid concentration in the electrolyte improved the degree of corrosion resistance of the coating layer.

Iris laevigata, which belongs to the Iridaceae, is now designated as an “endangered” (EN) grade by Korea Forest Service because it does not have many natural sites known for its reckless development and damage to its natural habitats. This study was carried out to establish the propagation protocol from seed to restore the native habitat of the I. laevigata and to utilize it for ornamental purposes. Basically, the appearance and internal structure of seeds were observed and imbibition experiments were conducted. Germination rate was measured by cold stratification experiment, after warm followed by cold stratification experiment, and GA3 treatment experiment. The seeds had underdeveloped embryos, which had grown to about 25% of those of fully matured seed before germination. In the controlled laboratory experiment, after cold stratification at 5°C for 0, 4, 8, or 12 weeks, the seeds germinated to 0, 11.7, 43.4, or 51.7%, respectively, after 4 weeks of incubation at 25°C. After warm stratification (25°C, 8 weeks) followed by cold stratification for 0, 4, 8, or 12 weeks, the seeds germinated to 0, 51.7, 85.0, or 88.3%, respectively, after 4 weeks of incubation at 25°C. GA3 treatment did not overcome the dormancy. Our study determined the dormancy type of I. laevigata seed. Imbibition experiments showed that there was no physical dormancy, and it was also found that there was an underdeveloped embryo when it was observed that the embryo was growing according to the period of incubation. A nd t he e m bryo grew a t relatively w arm temperatures. It is concluded that the seeds of I. laevigata have morphophysiological dormancy (deep simple MPD). This is the first report to determine the dormancy type in seeds of this valuable ornamental plant.

The lattice thermal expansion of zirconium-based samples containing tin, niobium, and iron elements at a temperature range of 30–870°C with intervals of 40°C was studied by in situ hightemperature X-ray diffraction (HT-XRD). The a- and c-axes lattice constants of the hexagonal Zr crystal structure for the zirconium-based samples were calculated by Pawley refinement using the in situ HT-XRD spectra. The a-axis lattice parameters for the zirconium-based samples with tin element overall decreased, whereas those for the samples containing niobium or iron elements are not declined, as compared to those for a pure zirconium sample. It suggests that the lattice thermal expansion along the a-axis direction of the hexagonal Zr crystal structure for zirconium-based samples was suppressed by the tin element. This effect is the greatest when the content of tin element added in zirconiumbased sample is 3wt%. On the other hand, the c-axis lattice parameters for all the zirconium-based samples overall increase as compared to the pure zirconium, indicating no suppression effect by tin, niobium, and iron elements, in contrast to the a-axis lattice constants.

Currently, dismantling technology for decommissioning nuclear power plants is being developed around the world. This study describes the cutting technology and one of the technologies being considered for the RV/RVI cutting of Kori Unit 1. The dismantling technology for nuclear power plants include mechanical and thermal methods. Mechanical cutting methods include milling, drill saw, and wire cutting. The advantages of the mechanical method are less generating aerosol and less performance degradation in water. However, the cutting speed is slow and the reaction force is large. Thermal cutting methods use heat sources such as plasma arcs, oxygen, and lasers. The advantages of thermal method are fast cutting speed, low reaction force and thick material cutting. On the other hand, they have problems with fume and melt. Among them, the cutability of the oxygen cutting method is better in carbon steel than in stainless steel. In order to cut the RV/RVI of the Kori Unit 1, the applicability of fine plasma, arc saw, and band/ wheel saw is being reviewed. For RV cutting, the applicability of arc saw and oxy-propane is being considered Because RV is mostly made of carbon steel. However, since the flange is cladded with stainless steel, the use of mechanical methods such as wire saws should be considered. In the case of RVI, since it has a complicated shape and is made of stainless steel, it seems necessary to review various cutting methods. In addition, it will be necessary to minimize radiation exposure of workers by cutting underwater cutting.

Many countries are developing various mechanical cutting technologies to dismantle nuclear facility. However, most of mechanical cutting technologies have a problem like the degradation of tool life due to the Hard-Machining materials. To solve this problem, lab-scale test was performed with a Plasma Assisted Machining (PAM) technology and 25 mm of thickness Inconel 600 plate. Commonly, the strength of metals decreases by exposure at high temperature. And, previous study reported that strength of Inconel 600 is degraded above 500°C. This softening effect was applied to Inconel 600 cutting test. The optimal conditions such as the plasma torch power and the feed rate were determined by this study. As a result, the surface temperature of Inconel 600 was reached up to 500°C under the conditions which is 8.4 kW of plasma torch power and 150–250 mm·min−1 of feed rate. And it was confirmed that the tool life was improved under the conditions. In order to apply PAM for various Hard- Machining materials, it is necessary to investigate the softening temperature of Hard-Machining materials, the plasma torch power and feed rate.

Various cutting technologies are being developed for dismantling nuclear power plants. these technologies are including mechanical and thermal methods. For example, mechanical cutting methods include sawing, drilling and milling. But, due to the strength of material, mechanical cutting methods have limits of cutting depth and tool life. Therefore, this milling machine assisted plasma torch was developed to improve the limits. And this machine has the principle of softening effect caused by the high temperature. In this work, this developed device was evaluated in view of the cutting depth and tool life in cutting process. For this process, a plasma torch was attached to the front of the endmill processing path to heat the Inconel 600. As results, compare to conventional milling, when the plasma torch power is 6.4 kW, the cutting depth was increased by 4 mm at condition (feed rate is 100 mm·min−1, tool diameter is 10 mm, rotating speed is 1,000 rpm). And cutting length increase 2 times from 300 mm to 600 mm at 16 mm of tool diameter.

This paper intends to present considerations on the question of what is the “load standard” or “design load” for integrity evaluation under normal transportation conditions and what type of design load is good for users. This suggests a direction for subsequent research on producing design loads that transport business companies can utilize without difficulty. Several studies have been conducted to evaluate the integrity of spent nuclear fuel during normal transportation. A representative study recently conducted is the Multi-modal Transportation Test (MMTT) conducted using a commercial spent nuclear fuel cask by US DOE in 2017. In Korea, additional transport tests were planned to acquire sufficient test data under the conditions of road and sea transport considering the Korean situation. As a result, road transport tests were carried out in 2020 and sea transport tests were carried out in 2021. In the road transport test, a driving test that simulates various road conditions and a test that cycled a 4.5 km road eight times were performed. In most cases, the maximum acceleration of less than 1 g occurred, and the maximum strain was less than 48 με. For the sea transport test, the magnitude of both the maximum acceleration and the maximum strain were lower than those in the road transport test. We concluded tentatively that the integrity of spent fuel under normal conditions of transport was satisfactory with a large margin. However, when the storage business is realized and the transport of spent fuel becomes visible, the storage and transport business companies will have to prove the maintenance of the integrity of the spent fuel under normal transport conditions at the request of the regulatory agency. The transport business companies can transport the spent nuclear fuel by using different types of transport casks and different types of trucks and ships from those used in the tests mentioned above. However, it is absurd to have to prove the integrity of spent nuclear fuel by performing expensive tests again. Therefore, in this study, the design load that can be used by transport business companies is to be presented. The design load to be presented should satisfy the following requirements. The design load should be applicable including some differences in the transport cask or transport system, or different design loads should be presented according to the differences. The location where this design load is applied is to be specified (e.g. fuel rod, basket, internal structure). Requirements according to the operating speed of the transport system should be presented together. The type of design load is to be presented (e.g. PSD, SRS, FDS etc.). Other types of standards may be presented. For example, a speed limit for a vehicle carrying spent nuclear fuel may be suggested, or a speed limit for a vehicle passing through a speed bump may be suggested. In order to present such a reliable design load, a multi-axis vibration excitation shaker table test will be carried out. Though this shaker table test, the behavior of the nuclear fuel assembly is closely evaluated by applying the data obtained from the road and sea transport tests previously performed as an input load. In addition, FDS (Fatigue Damage Spectrum) will be produced and applied to experimentally evaluate the durability of fuel assemblies under normal transport conditions.