• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.7
• /
• pp.931-941
• /
• 2020

There is a growing interest this paper for ocean sensing where autonomous vehicles can play an essential role in assisting engineers, researchers, and scientists with environmental monitoring and collecting oceanographic data. This study was conducted to develop a rigid sail for the autonomous sailing drone. Our study aims to numerically analyze the aerodynamic characteristics of curvy twin sail and compare it with wing sail. Because racing regulations limit the sail shape, only the two-dimensional geometry (2D) was open for an optimization. Therefore, the first objective was to identify the aerodynamic performance of such curvy twin sails. The secondary objective was to estimate the effect of the sail's spacing and shapes. A viscous Navier-Stokes flow solver was used for the numerical aerodynamic analysis. The 2D aerodynamic investigation is a preliminary evaluation. The results indicated that the curvy twin sail designs have improved lift, drag, and driving force coefficient compared to the wing sails. The spacing between the port and starboard sails of curvy twin sail was an important parameter. The spacing is 0.035 L, 0.07 L, and 0.14 L shows the lift coefficient reduction because of dramatically stall effect, while flow separation is improved with spacing is 0.21 L, 0.28 L, and 0.35 L. Significantly, the spacing 0.28 L shows the maximum high pressure at the lower area and the small low pressure area at leading edges. Therefore, the highest lift was generated.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.221-233
• /
• 2021

This study analyzed the contents of changes in educational policy from the perspective of policy learning, based on the awareness of the lack of academic efforts to identify such phenomena despite repeated policy failures in educational policy. To this end, it has been more than 20 years since the policy was established, but it was analyzed using the policy analysis case of the teacher incentive policy, which still had severe conflicts between the government and teacher unions. As a result of the analysis, first, there were 11 changes in the policy content from the Kim Dae-jung administration to the Moon Jae-in administration. Whenever the government was newly launched, not only the contents of the policy for teacher incentives changed, but also the policy changes continued during the same government period. Second, when analyzing what kind of policy learning took place at the stage of change in each government's policy content, most of them were 'political policy learning' or 'instrumental policy learning'. Rather than a fundamental discussion about the goal of the policy, it has only repeated policy learning that adjusts only the ratio of differential payments to defend the teacher incentive policy. In order to recover from this current situation, this study suggests that it is necessary to present an alternative policy that can change the rigid society of teachers through 'social policy learning', which examines the basic values and strategies of teacher incentive policies.

• Conservation Science in Museum
• /
• v.27
• /
• pp.1-22
• /
• 2022

A chimi(a roof ridge decoration) excavated from the Busosan Temple Site in Buyeo was restored in 1978 at the Buyeo Museum. The gypsum restoration material had deteriorated over time and part of it was seriously damaged and unable to bear the weight of the chimi. The chimi features traces of emergency treatment revealing that the inside of the body and some portions of the tail were reinforced several times using epoxy resin. A condition survey performed in preparation for its transfer for an exhibition found the lower body and wings of the chimi to be highly vulnerable and it was determined that the chimi needed further restoration. The dismantling of the chimi for restoration revealed several elements that provide clues to the production techniques applied by its makers, so they were subjected to inspection. This study explores the production techniques used in the chimi from the Busosan Temple Site that were revealed during the process of dismantling it for restoration. The chimi was inspected using 3D scanning and its rigid vertical shape was restored to a natural form based on the production techniques identified during the dismantling process. The existing restoration material was replaced to improve durability. 3D printed elements were produced based on 3D modelling and were joined to the original chimi to correct its shape and fill in the missing parts, restoring the chimi to its original appearance.

• Journal of Korean Foot and Ankle Society
• /
• v.26 no.2
• /
• pp.95-102
• /
• 2022

Purpose: This study was based on the Korean Foot and Ankle Society (KFAS) member survey and aimed to report the current trends in the management of syndesmotic injuries over the last few decades. Materials and Methods: A web-based questionnaire containing 36 questions was sent to all KFAS members in September 2021. The questions were mainly related to the preferred techniques and clinical experiences in the treatment of patients with syndesmotic injuries. Answers with a prevalence ≥50% of respondents were considered a tendency. Results: Seventy-six (13.8%) of the 550 members responded to the survey. The results showed that the most preferred method to diagnose a syndesmotic injury was magnetic resonance imaging (MRI). Intraoperatively, the external rotation stress test and the Cotton test were most frequently used to confirm syndesmotic diastasis. The reduction was usually done by a reduction clamp. One 3.5-mm screw was used most frequently over three cortices at 2~4 cm above the ankle joint. The preferred ankle position during fixation was 0° dorsiflexion. Removal of the syndesmotic screw was routinely done by most surgeons, mainly because of the limitation of movement and risk of screw breakage. Factors that affect suture button selection included non-rigid fixation which enables adequate fixation, early weight-bearing, and an infrequent need to remove the hardware. Inadequate reduction was considered the main factor that affects poor prognosis. Conclusion: This study proposes updated information about the current trends in the management of syndesmotic injuries in Korea. Consensuses in both the diagnostic and therapeutic approach to patients with syndesmotic injury were identified in this survey study. This study may raise the awareness of the various possible approaches toward the injury and should be used to further establish a standard protocol for the management of syndesmotic injuries.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.32 no.4
• /
• pp.67-88
• /
• 2021

The National Science and Technology Standard Classification System is established and operated for the purpose of efficiently managing science and technology related information, manpower, and R&D projects. The revision cycle for the classification system is five years, and 2022 is the first year of the next revision procedures. The main purpose of the next revision is to turn the third level categories into the keywords in the current classification system. It is to solve the problems about not reflecting the latest terms, and the difficulty in linking with the relevant other classifications caused by the rigid structure of the current classification system. In this study, the method was proposed by changing the existing classification system into the term management system as to improve the quality and usability of keywords related with the current third level categories. For this method, SKOS, the international standard terminology management system, and ISO/IEC 11179 standards were offered as basic models. In addition, the related metadata standards used in overseas scientific and technological glossaries were investigated, and compared with the current National Science and Technology Standard Classification System. And then essential metadata elements from the terminology management as point of view was derived. As a result, 11 standard metadata elements that can be immediately modified and applied in the current system were recommended, and five elements that can be applied after the revision of the classification system were offered.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.12
• /
• pp.41-50
• /
• 2021

This study investigated the changes in engineering characteristics of sand-tire chip mixtures during repetitive loading. To quantify the changes in the maximum shear modulus according to the tire chip content in the mixtures and the particle size ratio between sand particle and tire chip, the samples were prepared with tire chip content of TC = 0, 10, 20, 40, 60, and 100%, and the particle size ratios SR were also set to be SR = 0.44, 1.27, 1.87, and 4.00. The stress of the prepared sample was applied through a pneumatic cylinder. The experiment was conducted in the order of static loading (= 50 kPa), cyclic loading (= 50-150 kPa), static loading (= 400 kPa) and unloading. The stress applied to tested mixtures was controlled by a pressure panel and a pneumatic valve by using an air compressor. The shear wave velocity was measured during static and cyclic loadings by installing bender elements at the upper and lower caps of the mold. The results demonstrated that the change in maximum shear modulus of all tested materials with varying SR during repetitive loading is the most significant when TC ~ 40%. In addition, the mixture with smaller SR at a given TC shows greater increase in maximum shear modulus during repetitive loading.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.10
• /
• pp.31-40
• /
• 2022

This study compares elastic moduli calculated using two stiffness testing methods with different strain ranges to evaluate the stress-settlement characteristics of foundation support layers. Elastic moduli were calculated by the soil stiffness gauge (SSG) in the micro-strain range and the plate load test (PLT) in the medium strain range. To apply the elastic moduli obtained by the two testing methods with different strain ranges to the design and construction of foundation soils, the correlation between each measurement value should be identified in advance. As a result of the comparative analysis of the elastic moduli calculated using the two methods in weathered soil and rock, which are representative support layers in Korea, the calculated elastic moduli differed depending on the types of soil and stress conditions. For various soil types, the static elastic modulus obtained by the PLT was reduced by 56% because of the difference in the strain level of the test compared with the dynamic elastic modulus obtained by the SSG. Therefore, the results show that it is necessary to apply corrections to the stress distribution, stress level, and dynamic effect according to the ground stiffness to effectively use the SSG instead of the PLT.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.5
• /
• pp.1-6
• /
• 2021

Mercury, once released, is not destroyed but accumulates and circulates in the natural environment, causing serious harm to ecosystems and human health. In the United States, sulfur-impregnated activated carbon is being considered for the removal of vapor mercury from the flue gas of coal-fired power plants, which accounts for about 32 % of the anthropogenic emissions of mercury. In this study, a high-efficiency porous mercury adsorption material was developed to reduce the mercury vapor in the exhaust gas of coal combustion facilities, and the mercury adsorption characteristics of the material were investigated. As a result of the investigation of the vapor mercury adsorption capacity at 30℃, the silica nanotube MCM-41 was only about 35 % compared to the activated carbon Darco FGD commercially used for mercury adsorption, but it increased to 133 % when impregnated with 1.5 % sulfur. In addition, the furnace fly ash recovered from the waste copper regeneration process showed an efficiency of 523 %. Furthermore, the adsorption capacity was investigated at temperatures of 30 ℃, 80 ℃, and 120 ℃, and the best adsorption performance was found to be 80 ℃. MCM-41 is a silica nanotube that can be reused many times due to its rigid structure and has additional advantages, including no possibility of fire due to the formation of hot spots, which is a concern when using activated carbon.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.167-174
• /
• 2022

The objective of this study is to evaluate the dynamic properties of DUS (damping-up system) composed of the materials with excellent damping capacity, and to compare with those of the conventional hangar bolt. The main parameters are the type and hardness (𝜂_H), of rubber and the prestress force (value converted from the compression strain (𝜂_R) in the stress-strain relationship of rubber). The dynamic properties were examined from the natural frequency (𝜔_n), maximum response acceleration (A_m), amplification coefficient (𝛼_p), maximum relative displacement (𝚫_m), and damping ratio (𝜉_D). The test results showed that the A_m, 𝛼_p, and 𝚫_m values of DUS were 46.3%, 46.6% and 62.9% lower, respectively, and the 𝜉_D value was 3.89 times higher, when compared to those of the conventional hangar bolt. In particular, the 𝛼_p value was 1.3 for DUS, and 2.45 for the conventional hanger bolt, which were similar to those of rigid and flexible components specified in KDS 41 17 00, respectively. Consequently, in the optimal details of DUS, the 𝜂_H values of 50 and 45 were required for the NR (natural rubber) and EPDM (ethylene propylene diene monomer), and the 𝜂_R value of 5% was also recommended.

• Korean Journal of Mineralogy and Petrology
• /
• v.35 no.3
• /
• pp.259-271
• /
• 2022

Lattice preferred orientation (LPO), which shows a specific lattice-orientation of minerals, is affected by the deformation conditions of minerals. Because of this reason, LPO is very useful to study the deformation conditions of the minerals and the rocks. In this study, we collected amphibole-rich rocks from the Geumgye Mountain, Chugye-ri, Yugu-eup, Chungcheongnamdo, located in the southwestern part of the Gyeonggi Massif, and analyzed the LPO of amphibole and plagioclase using electron backscattered diffraction. Two types of LPOs of amphibole, type I and type IV, were observed in Yugu amphibole-rich rocks. Our data suggest that the amphibole-rich rocks in Yugu were deformed by rigid body rotation regardless of the LPOs and grain size of amphibole, and the LPOs are considered to have been affected by the degree of deformation (i.e. strain). In the low strained amphibole-rich rock, a strong type I LPO and a large grain size of amphibole were observed. On the other hand, in the highly strained amphibole-rich rocks, a weak type IV LPO and a small grain size of amphibole were observed. The various degree of deformation observed in the Yugu amphibole-rich rocks were also observed in the adjacent peridotites, indicating that the rocks in Yugu experienced various levels of deformation.