본 연구는 미국의 동아시아 안보전략과 해외주둔군 전략, 확장억제전 략의 변화를 분석하고, 북한의 핵무기 고도화에 대비한 주한미군과 핵우 산 정책을 고찰한다. 한미동맹이 체결된 1953년 이후, 미국은 한반도 안 보의 중심 역할을 수행했으나 비대칭 동맹으로 인한 동맹 딜레마와 미군 의 역할 및 규모 변화가 발생했다. 핵우산 정책은 냉전기 소련의 핵전술 에 대항하여 확장되어 현재까지 적용되고 있으며, 2023년에는 워싱턴 선 언을 통해 한미 핵협의그룹(NCG)이 창설되었다. 이를 통해 상시적인 확 장억제가 논의되고 있으며, 굳건한 한미 동맹체제와 안보공약이 SCM을 통해 재확인되었다. 이제는 냉전 시기의 미군 주둔과 자동개입 문제는 중국의 G2국가 발전, 북한의 핵과 미사일 도발 등으로 시대적 변수가 달 라져 있다. 따라서 미국의 주한미군 정책, 개입 문제, 확장억제전략에 대 한 신중한 검토와 대비가 필요하다. 본 연구는 미국의 동아시아 전략, 주 한미군, 확장억제전략에 대해 고찰하고 한반도 안보에 대한 전망을 목적 으로 한다.

In this study, we examined dimensional changes in processing carbon fiber composites using a cost-competitive domestic high-speed router. Lacking temperature compensation features found in typical machines, it faces increased defect rates due to temperature fluctuations during processing. To mitigate this, we defined specific processing temperature conditions, established hole positions as distance references for various temperatures, and measured dimensional changes. This enabled us to calculate necessary dimensional corrections, minimizing thermal deformation.

Prepreg is an abbreviation of Preimpregnated Materials. It is a sheet-type product in which a matrix is ​​impregnated with reinforced fiber. The prepreg has very different properties depending on the orientation of the fibers and the weaving method, and the orientation of the fibers plays an important role in determining the mechanical strength of CFRP. Short and randomly oriented reinforcing fibers show isotropy, while long, unidirectional reinforcing fibers exhibit anisotropic behavior and are strongest when the applied load is parallel to the reinforcing fibers. Classification by the direction of the fiber is divided into unidirectional, orthogonal, multiaxial, and the like. Uni-directional refers to a state in which almost all fibers in the fabric are aligned in one direction. When the fibers used as reinforcing materials are aligned in one direction, the fibers are used in a straight line without twisting during the fabric production process, and there is an advantage in that the amount of fibers used as a whole can be minimized. A uni-directional prepreg exhibits different cutting forces depending on the stacking orientation angle. In this experiment, the optimal cutting conditions for a uni-directional prepreg 45 degree orientation angle specimen are presented.

In the context of the 4th Industrial Revolution, the rise of electric vehicles and personal mobility is evident. However, regulatory authorities seem to overlook vast opportunities, placing two-wheelers in a deregulated category and focusing mainly on regulations. This paper addresses a notable trend in e-mobility, emphasizing aspects often overlooked in traditional motorcycle regulatory research. Using the industrial life cycle theory as a basis, we identify challenges that have affected traditional combustion-engine two-wheelers and offer insights to navigate similar obstacles in the future. Consequently, the domestic two-wheeler market experienced a brief surge but lacked sustainable growth prospects. However, considering Japan's success in establishing global standards and design dominance in the two-wheeler industry despite its late entry, there appears to be potential for a rebound in the domestic market.

During the initial construction of Won buddhism, the sound absorbing material and diffusion material were used in the interior of the Won buddhism, so the sound performance at each buddhism could not be secured above a certain level, and even in the case of the Won buddhism Bukil dharma hall, the reverberation and volume of the sound generated inside the sanctum was too loud, and since the establishment of the buddhism continued to be dissatisfied, the improvement of the acoustic performance was very urgent. From this perspective, this study measured acoustic performance of the Bukil dharma hall before remodeling, determined the acoustic defects and status, and used acoustic simulation to present three plans for improving acoustic performance. Taking economic feasibility, construction, and construction duration into account, remodeling was performed on the basis of Plan 1 and post-remodeling acoustic performance was measured for comparative analysis of acoustic performance between before and after the improvement. The results of study, before and after sound performance improvement sound pressure level (SPL500Hz) was 71.9dB at 79.4dB , the weighted sound level (SPLdB(A)) was 79.7dB(A) at 89.4dB(A), reverberation time (RT500Hz) was 1.12sec at 1.49sec, early decay time (EDT500Hz) was 1.39sec at 1.63sec, definition (D50,500Hz) was 34.9% at 32.3%, clarity (C80.500Hz) was 1.0dB at –0.4dB, and RASTI was 60.0%(“Good”) at 51.3%(“Fair”) was evaluated. Therefore, the Bukil dharma hall was after remodeling, neither definition(D50) improved notably but excessive volume and reverberation and sound mixing almost disappeared and acoustic performance improved so much that many different events and services could be held.

The need for lightweight yet strong materials is being demanded in all industries. Carbon fiber-reinforced plastic is a material with increased strength by attaching carbon fiber to plastic, and is widely used in the aerospace industry, ships, automobiles, and civil engineering based on its low density. Carbon-reinforced fiber plastic is a material widely used in parts and manufactured products, and structural analysis simulation is required during design, and application of actual material properties is necessary for accurate structural analysis simulation. In the case of carbon-reinforced fiber plastics, it is reported that there is a porosity of around 0.5% to 6%, and it is necessary to check the change in material properties according to the porosity and pore shape. It was confirmed by applying the method. It was confirmed that the change in elastic modulus according to the porosity was 10.7% different from the base material when the porosity was 6.0%, and the Poisson's ratio was confirmed to be less than 3.0%. It was confirmed that the elliptical spherical pore derived different material properties from the spherical pore depending on the pore shape, and it was confirmed that the shape of the pore had to be confirmed to derive equivalent material properties.

In this study, numerical analysis was performed for the purpose of analyzing the flow characteristics and performance according to the change in the inflow hydrogen temperature and differential pressure of the receptacle of the hydrogen charging system. The pressure distribution and turbulent kinetic energy in the filter area were analyzed by changing the outlet pressure condition under the inlet hydrogen temperature condition, and the flow velocity change at the outlet was compared and analyzed. As a result of the analysis, as the differential pressure decreased, the flow rate at the outlet of the receptacle decreased by up to about 70% at the 2.86 MPa condition compared to the 1.86 MPa condition, and the mass flow rate decreased by about 56.5% at the maximum. It was found that the standard CV performance was not satisfied when the differential pressure at the inlet and outlet was 1.12 MPa or less under the 363K temperature condition.

This study aimed to assess and determine the optimal model for predicting the full bloom date of ‘Fuji’ apples across South Korea. We evaluated the performance of four distinct models: the Development Rate Model (DVR)1, DVR2, the Chill Days (CD) model, and a sequentially integrated approach that combined the Dynamic model (DM) and the Growing Degree Hours (GDH) model. The full bloom dates and air temperatures were collected over a three-year period from six orchards located in the major apple production regions of South Korea: Pocheon, Hwaseong, Geochang, Cheongsong, Gunwi, and Chungju. Among these models, the one that combined DM for calculating chilling accumulation and the GDH model for estimating heat accumulation in sequence demonstrated the most accurate predictive performance, in contrast to the CD model that exhibited the lowest predictive precision. Furthermore, the DVR1 model exhibited an underestimation error at orchard located in Hwaseong. It projected a faster progression of the full bloom dates than the actual observations. This area is characterized by minimal diurnal temperature ranges, where the daily minimum temperature is high and the daily maximum temperature is relatively low. Therefore, to achieve a comprehensive prediction of the blooming date of ‘Fuji’ apples across South Korea, it is recommended to integrate a DM model for calculating the necessary chilling accumulation to break dormancy with a GDH model for estimating the requisite heat accumulation for flowering after dormancy release. This results in a combined DM+GDH model recognized as the most effective approach. However, further data collection and evaluation from different regions are needed to further refine its accuracy and applicability.