When a permanently-closed nuclear power plant is to be decommissioned, large structures targeted to be cut in the process include a steam generator, reactor, and reactor coolant pump (RCP). Although there are sufficient preliminary studies being done on these structures to assess the radiation exposure dose, relatively fewer studies are underway regarding pressurizers. Therefore, preliminary evaluations are required to prevent workers from being overexposed to radiation coming from a pressurizer and to avoid an unnecessary increase in the decommissioning cost. This study created a cutting scenario based on disposal drums for solid radioactive wastes. The cutting scenario was based on 200-liter and 320-liter drums for solid wastes and on the assumption that all cutting operations were done 100 centimeters away from the structure to be cut. When are cutting process of a Pressurizer is carried out per scenario, the 200-liter drum produces 272 pieces, whereas the 320-liter counterpart generates 234 pieces. Given that South Korea allocates 75,550 KRW per liter (based on 200 L) for the disposal cost, an increase in the number of drums leads to an exponential growth of the decommissioning cost, which fuels the need to establish more organized cutting strategies. Meanwhile, in terms of radiation dose, plasma, laser, and flame cutting techniques were estimated to record 0.232 mSv, 0.299 mSv, and 0.213 mSv respectively for 200 L, and 0.195 mSv, 0.251 mSv, and 0.179 mSv respectively for 320 L (based on DF-90). When compared with the annual dose limit of 100 mSv (0.0057 mSv·hr−1), the above numbers registered for both 200 L and 320 L were estimated to satisfy the dose limit, with only a negligible difference in the dose between the two capacities. The results generated from this study are expected to be utilized as a meaningful basis to identify applicable cutting techniques of a pressurizer as part of the decommissioning operation and to establish its cutting plans in compliance with ALARA.

The dismantling of the reactor pressure vessel has been carried out at a number of commercial nuclear power plants, including the Zion nuclear power plant in the United States and the Stade nuclear power plant in Germany. The dismantling method for the reactor pressure vessel is either in the air or in the water, depending on the utility. In general, a mechanical cutting method is used when dismantling the reactor pressure vessel in the water. And when dismantling a nuclear reactor pressure vessel in the air, the thermal cutting method is applied. However, there is no case of dismantling commercial nuclear reactor pressure vessel by applying a mechanical method in the air. In this study, when a nuclear reactor pressure vessel is dismantled by applying a mechanical method in the air, the applicability was evaluated by testing it using a demonstration mockup of Kori Unit 1. For the evaluation, the mockup was made in the actual size of Kori Unit 1. Mechanical cutting devices used the band saw and the circular saw. In the test, the cutting of the reactor pressure vessel was performed remotely by reflecting the working conditions of the decommissioning site. The band saw cutting method was applied to vertical cutting, and the circular saw cutting method was applied to horizontal cutting. In order to dismantle one cut-off piece, mockup test was performed according to a series of dismantling processes, it consists of preparatory work, vertical cutting process, horizontal cutting process, packaging process and finishing work. The cutting speed of the band saw is 3–10 mm·min−1, and the cutting speed of the circular saw is 2–4 mm·min−1. As a result of the test, when the mechanical cutting method was applied, as is known, the kerf width was smaller than when the thermal cutting method was applied. The cut surface showed a clean state without drag lines generated during thermal cutting. However, the working time was much slower than when the thermal cutting method was applied.

In thermal cutting process, gas flow injected from the nozzle has a significant effect on the cutting materials. The gas flow is difficult to observe gases are transparent, therefore, in this study, Schlieren method was adopted to visualize the gas flow inside the kerf. The kerf shape was inserted between two slices of transparent glass in order to imitate the real cutting environment. In order to get the flow characteristics, a high speed camera was equipped and the image processing was applied to compare the before and after injection images. As a result, the method for visualizing gas flow was successfully developed and also expected to be applied to the analysis of purging gas in various welding environments.

A 13-year-old mixed dog was referred to the animal medical center, Gyeongsang National University. Lung masses were diagnosed at the left cranial and caudal lobes through diagnostic imaging, and consequently, left pneumonectomy was performed using a self-cutting linear endoscopic stapler. The pulmonary arteries, veins, and bronchus of each lung lobe were sealed and resected at once, and any air leakage or bleeding was not observed after the surgery. Compared to the conventional ligation method, the self-cutting linear endoscopic stapler has the advantage of significantly reducing the operation time and enabling simple and reliable sealing.

본 연구는 스탠다드 국화 ‘백마’의 삽목기간(15, 30, 45일)과 단일처리 시기(정식 후 40, 50, 60, 70일 후)에 따른 버들눈 발생과 절화의 생육에 미치는 영향을 알아보기 위해 실시하였다. 삽목기간이 30일과 45일 처리는 15일 처리보다 초장이 길었고 뿌리수가 많았으나, 잎의 황화현상이 나타났다. 삽목기간이 길수록 정식 후 버들눈 발생률이 높았고, 삽목기간이 45 일 처리에서 버들눈의 발생률이 28.3%로 가장 높았다. 절화의 생육에서 절화장은 삽목기간 15일 처리에서 110.9cm로 가장 길었고, 삽목기간이 길수록 절화장이 짧았다. 절화의 엽수와 무게는 삽목기간 15일 처리에서 가장 양호하였다. 화폭, 설상화 수, 꽃 무게 등 꽃의 생육은 삽목기간이 길어질수록 불량하였고, 꽃목길이는 삽목기간 30일과 45일 처리에서 6.5~8.9cm 로 길게 나타나 절화의 품질이 떨어졌다. 개화소요일수는 다른 처리들보다 삽목기간 45일 처리에서 버들눈 발생으로 인하여 가장 짧았다. 단일처리 시기에 따른 절화의 버들눈 발생률은 정식 60일과 70일 후 단일처리에서 각각 20.1%와 45.8%로 나타나, 정식 40일과 50일 후 단일처리보다 높게 나타났다. 절화의 길이, 엽수, 무게 등의 절화 생육은 영양생장기간이 길었던 정식 70일 후 단일처리에서 가장 양호하였고, 정식 40일 후 단일처리에서 가장 불량하였다. 그러나 화폭, 설상화수, 꽃의 무게 등의 꽃의 생육은 정식 50일 후 단일처리에서 가장 우수하였다. 정식 60일과 70일 단일처리에서 꽃목에 유엽이 발생함에 따라 꽃목길이가 길어져 품질이 하락하였고, 개화소 요일수는 단일처리 시기가 늦을수록 지연되었다. 따라서 스탠다드 국화 ‘백마’의 버들눈은 삽목기간이 길어져 15일 이상된 노화된 삽목묘를 정식하거나 정식 후 단일처리 시기가 50일 이상으로 늦어질 경우에 많이 발생하며, 버들눈 발생으로 화폭, 설상화수, 꽃 무게, 꽃목길이 등 절화의 품질이 크게 하락하는 것으로 나타났다.

The cutting quality of abrasive water jet cutting of aluminum alloy(Al-5083) for shipbuilding is affected by the surface roughness, cutting pressure, cutting speed, and the distance between nozzle and material. The cross-section of water jet cutting is formed a V-shape as the cutting speed increase. The upper width(kerf width) is wide and the lower surface is narrow. The width of cutting cross-sections are effected in the order of cutting speed, cutting pressure, and distance between nozzle and material. From the experimental results, to improve of cutting quality of abrasive water jet cutting of aluminum alloy(Al-5083) for shipbuilding, the optimal cutting conditions to improve the surface roughness and kef width are proposed and discussed.

SiAlON-based ceramics are a type of oxynitride ceramics, which can be used as cutting tools for heatresistant super alloys (HRSAs). These ceramics are derived from Si3N4 ceramics. SiAlON can be densified using gaspressure reactive sintering from mixtures of oxides and nitrides. In this study, we prepare an α-/β-SiAlON ceramic composite with a composition of Yb0.03Y0.10Si10.6Al1.4O1.0N15.0. The structure and mechanical/thermal properties of the densified SiAlON specimen are characterized and compared with those of a commercial SiAlON cutting tool. By observing the crystallographic structures and microstructures, the constituent phases of each SiAlON ceramic, such as α- SiAlON, β-SiAlON, and intergranular phases, are identified. By evaluating the mechanical and thermal properties, the contribution of the constituent phases to these properties is discussed as well.

도법으로 풀어내는 매체 특징을 가진 전각예술은 중국 서화와 구별될 뿐만 아니라 문화 속성을 가지고 있기에 다른 문화 속 새김 예술들과 차이가 나므로 전각의 주요한 형식 요소로 간주 된다. 현대 문화 속에서, 전각에서의 칼이 자아내는 미적 의미는 중국예술전통을 계승함과 동시에 현대전각의 품평과 평가 기준에 새로운 의미를 부여했다. 중국의 고대 시품을 기본 형식으로 삼아 당대 정신에 부합하는 미적 계보와 체계적 틀 구축은 그 의의가 매우 중대하다고 본다. 이를 위해 본 논문에서는 원형에 맞는 우아미 등의 평가 기준과 근거로 4가지 미적 유형을 제안한다.

Molds are actively used for mass production of products such as mobile phones. Molds are required to be durable and have a high level of surface roughness. Therefore, the optimization of mold processing is essential. In this study, the cutting processing of SDP20 steel used in molds was analyzed and optimized. This study is expected to contribute to the improvement of product productivity to which plastics are applied.

유인 방법은 딸기 묘를 생산하는 전통적인 방법이다. 그러나 딸기 묘를 유인하여 번식하는 방법은 오랜 노동시간이 있어야 하는 노동 집약적인 방법이다. 삽목 방법은 상대적으로 유인 방법에 비해 노동 기간과 작업 시간이 짧으므로 유인의 효과적인 대안으로 주목되어왔다. 이 연구는 유인과 삽목 사이의 노동 기간, 작업 시간 및 묘의 생육을 조사하기 위해 수행되었다. ‘매향’ 딸기는 두 개 동의 딸기 육묘용 유인 온실과 삽 목 온실에서 각각 재배되었다. 유인 방법(유인 작업, 모주 제거, 자묘 간 분리) 및 삽목 방법(삽수 채묘, 저장 전 처리, 삽목 작업)에 대한 주요 작업 시간을 측정했으며, 유인은 158일 동 안 6개의 작업이 필요하며, 삽목은 113일 동안 4개의 작업이 필요했다. 유인은 삽목보다 작업 시간이 더 많이 필요했다. 유인과 삽목묘 육묘 방법에 따른 유의적인 차이가 없었다. 이러한 결과는 묘소질의 손실 없이 육묘 동안 유인 방법보다 삽목 방법이 더 많은 노동 기간과 작업 시간을 절약할 수 있음을 의미한다.

For application in nuclear decommissioning, underwater laser cutting studies were conducted on thick stainless-steel plates for various cutting directions using a 6 kW fiber laser. For cutting along the horizontal direction with horizontal laser irradiation, the maximum cutting speed was 110 mm∙min−1 for a 48 mm thick stainless-steel plate. For cutting along the vertical direction with horizontal laser irradiation, a maximum speed of 120 mm∙min−1 was obtained for the same thickness, which confirmed that the cutting performance was similar but slightly better. Moreover, when cutting with vertically downward laser irradiation, the maximum cutting speed was 120 mm∙min−1 for a plate of the same thickness. Thus, the cutting performance for vertical irradiation was nearly identical to that for horizontal irradiation. In conclusion, it was possible to cut thick stainless-steel plates regardless of the laser irradiation and cutting directions, although the assist gas rose up due to buoyancy. These observations are expected to benefit laser cutting procedures during the actual dismantling of nuclear facilities.

This study was conducted to estimate the effect of different cutting lengths on fermentation characteristics and aerobic stability of whole crop rice (WCR) silage. The WCR was harvested at the yellow ripe stage (43.7%, DM), and then cut at 5 (R05), 10 (R10), and 20 cm (R20) of the theoretical length of cut with no cut WCR (R60). Each forage was ensiled into 20 L mini bucket silo (5 kg) for 150 days in quadruplicates. The cutting lengths were not affected the chemical compositions of WCR silage (p > 0.05). The pH (p < 0.001) and concentration of ammonia-N (p = 0.022) in WCR silage were increased linearly with the increase of cutting length. The concentration of lactate had quadratic effect (p = 0.007), which was highest in R20 silage (p < 0.05). The concentration of acetate was increased linearly (p = 0.014), but the concentration of butyrate was decreased linearly (p = 0.033). The lactic acid bacteria count was decreased linearly (p = 0.017), and yeast count had quadratic effect (p = 0.009), which was the highest in R20 silage (p < 0.05). Aerobic stability had strong quadratic effect (p < 0.001), which was the highest in R20 silage (p < 0.05). In conclusion, R60 silage had highest pH by a linear increase of ammonia-N concentration and led to low aerobic stability. While R20 silage had the lowest pH by high lactate concentration and led to high aerobic stability.

Cutting management has been identified as a critical factor in the alfalfa production systems because it has a significant impact on maximizing yield and maintaining the forage quality. The objective of this experiment was to determine the proper cutting height according to harvesting time for optimizing nutrient yield and forage nutritive quality of alfalfa grown in alpine regions of Korea. Alfalfa was sown at a seeding rate of 30 kg/ha in August 2018 and harvested at four cuttings in 2019 (3 May, 2 July, 11 September, and 13 October). Cutting heights were adjusted at 5, 15, and 25 cm above the soil surface. Alfalfa plant was tallest at the third cutting (109 cm), which was on average 35 cm taller than the first or second cutting. Relative feed value (RFV) remained unaffected by cutting height at the first harvest, but increased consistently in subsequent harvests as cutting height increased. Alfalfa collected at the first and fourth cuttings had the highest RFV (mean 152), which was on average 8 and 67 units higher than the second and third harvests, respectively. At each harvest, in vitro dry matter digestibility was highest in alfalfa cut at a 25-cm height. Dry matter (DM) production at each cutting height was highest in the first cutting, accounting for on average 36-37% of total annual DM production, and lowest in the fourth harvest, accounting for about 11-13% of the total DM yield. The total dry matter production (in four harvests) was 4,218 kg/ha higher when alfalfa was subjected to a cutting height of 5 cm rather than 25 cm. Cutting height had no effect on total crude protein yield, but from the first to fourth cutting, the protein yield followed a decreasing trend. Finally, there were visible declines in forage nutritive quality when alfalfa was cut at a shorter height. However, the magnitude of difference in total forage yield may outweigh the slight decline in forage quality when alfalfa is cut at a lower height. The findings of this study could help the alfalfa growers make better harvest management decisions.