Buckling Restrained Braces can not only express the strength considered at the time of design, but also reduce the seismic load by energy dissipation according to the plastic behavior after yield deformation of the steel core. The physical characteristics and damping effect may be different according to the buckling prevention method of the steel core by the lateral restraint element. Accordingly, in this study, To compare hysteresis characteristics, Specimen(BRB-C) filled with mortar, specimen(BRB-R) combined with a buckling restraint ring and Specimen(BRB-EP) filled with engineering plastics was fabricated, and a cyclic loading test was performed. As a result of the cyclic loading test, the maximum compressive strength, cumulative energy dissipation and ductility of each test specimen was similar. But in case of the cumulative energy dissipation and ductility, BRB-C filled with the mortar specimen showed the lowest. This is considered to be because the gap between the steel core and the reinforcing material for plastic deformation was not uniformly formed by pouring mortar around the core part.

This study proposes an RCS composite damping device that can achieve seismic reinforcement of existing buildings by dissipating energy by inelastic deformation. A series of experiments assessing the performances of the rubber core pad, hysteretic steel slit damping device, and hybrid RCS damping device were conducted. The results showed that the ratios of the deviations to the mean values satisfied the domestic damping-device conformity condition for the load at maximum device displacement in each direction, at the maximum force and minimum force at zero displacement, as well as the hysteresis curve area. In addition, three analysis models based on load-displacement characteristics were proposed for application to seismic reinforcement design. In addition, the validity of the three proposed models was confirmed, as they simulated the experimental results well. Meanwhile, as the shear deformation of the rubber-core pad increased, the hysteretic behavior of super-elasticity greatly increased the horizontal force of the damping device. Therefore, limiting the allowable displacement during design is deemed to be necessary.

In this study, an incremental loading test of the HRS(Hybrid Rubber Slit) damper was additionally performed to define the physical characteristics according to the incremental test results, and an analytical study was performed according to the damping design procedure by selecting an example structure. As a result of performing seismic performance evaluation before reinforcement by selecting a RC structure similar to an actual school structure as an example structure, the story drift ratio was satisfied, but some column members collapsed due to bending deformation. In order to secure the seismic performance, the damping design procedure of the HRS damper was presented and performed. As a result of calculating the amount of damping device according to the expected damping ratio and applying it to the example structure, the hysteresis behavior was stable without decrease in strength, and the story drift ratio and the shear force were reduced according to the damping effect. Finally the column members that had collapsed before reinforcement satisfied the LS Level.

It is effective to apply hybrid damping device that combine separate damping device to cope with various seismic load. In this study, HRS hybrid damper(hybrid rubber slit damper) in which high damping rubber and steel slit plate are combined in parallel was proposed and structural performance tests were performed to review the suitability for seismic performance. Cyclic Loading tests were performed in accordance with criteria presented in KDS 41 17 00 and MOE 2019. As a result of the test, the criteria of KDS 41 17 00 and MOE2019 was satisfied, and the amount of energy dissipation increased due to the shear deformation of the high-damping rubber at low displacement. Result of performing the RC frame test, the allowable story drift ratio was satisfied, and the amount of energy dissipation increased in the reinforced specimen compared to the non-reinforced specimen.

Changes in the mechanical properties and microstructure of an IN 939 W alloy according to the sintering heating rate were evaluated. IN 939 W alloy samples were fabricated by spark plasma sintering. The phase fraction, number density, and mean radius of the IN 939W alloy were calculated using a thermodynamic calculation. A universal testing machine and micro-Vickers hardness tester were employed to confirm the mechanical properties of the IN 939W alloy. X-ray diffraction, optical microscopy, field-emission scanning electron microscopy, Cs-corrected-field emission transmission electron microscopy, and energy dispersive X-ray spectrometry were used to evaluate the microstructure of the alloy. The rapid sintering heating rate resulted in a slightly dispersed γ' phase and chromium oxide. It also suppressed the precipitation of the η phase. These helped to reinforce the mechanical properties.

A typical trade-off relationship exists between strength and elongation in face-centered cubic metals. Studies have recently been conducted to enhance strength without ductility reduction through surface-treatment-based ultrasonic nanocrystalline surface modification (UNSM), which creates a gradient microstructure in which grains become smaller from the inside to the surface. The transformation-induced plasticity effect in Fe-Mn alloys results in excellent strength and ductility due to their high work-hardening rate. This rate is achieved through strain-induced martensitic transformation when an alloy is plastically deformed. In this study, Fe-6%Mn powders with different sizes were prepared by high-energy ball milling and sintered through spark plasma sintering to produce Fe-6%Mn samples. A gradient microstructure was obtained by stacking the different-sized powders to achieve similar effects as those derived from UNSM. A compressive test was performed to investigate the mechanical properties, including the yielding behavior. The deformed microstructure was observed through electron backscatter diffraction to determine the effects of gradient plastic deformation.

게임을 구현하는 동안 주기성을 보장해야될 필요성이 있는 경우가 많이 있다. 예를 들어 많은 경우에 캐릭 터의 충돌은 주기적으로 처리되어야 될 필요성이 있는데 주기적으로 처리하지 못하는 경우 게임에서 충돌 을 감지하지 못하는 경우가 발생할 수 있다. 또한 슈팅 게임에서는 많은 경우에 사용자의 편의를 위하여 특 정 버튼을 누르면 무기를 자동적으로 발사하는 기능을 포함하고 있어 주기적으로 무기를 발사해야될 필요 성이 있다. 한편 유니티를 사용하여 게임을 구현할 때 이러한 주기성을 보장하기 위해서 WaitForSeconds로 지연을 발생시킨 코루틴, InvokeRepeating, FixedUpdate, .NET의 Timers.Timer가 사용될 수 있다. 그러나 이러한 다양한 방법들로 인하여 방법의 선택에 어려움이 있어 연구를 진행하였다. 본 연구에서는 1분 동안 6000번 메서드를 주기적으로 실행하고 주기성과 횟수를 측정하였다. 또한 다양한 환경에서의 실험을 위하여 추가의 모델 렌더링이 없는 경우와 렌더링을 추가한 경우, 다양한 해상도에서 주기성과 메서드 호출 횟수를 모두 측정했다. 실험 결과, 부하가 적은 환경에서는 InvokeRepeating이 가장 6000회에 가까웠으며 부하가 큰 환경 에서는 Timers.Timer가 가장 6000회에 가까웠으며 실행 주기의 편차가 가장 적었다. 이러한 실험들을 통하여 유니티를 통하여 게임을 구현할 때 일정 시간 내에 실행되는 횟수가 중요한 게임에서 성능 부하가 크지 않 은 경우 InvokeRepeating을, 성능 부하가 크다면 .NET의 Timer를 쓰는 것이 적합함을 알아내었다. 본 연구를 통하여 개발자는 유니티에서 제공되는 주기성 제공 방법들 중에서 적절한 방법을 선택할 수 있다.

Unlike the CFT retrofit method, The EPFT retrofit method, which fills the steel tube with engineering plastic, does not require a separate concrete forming work and is a lightweight seismic Retrofit Method. In this study, an prototype model of the EPFT was proposed, and to analyze the seismic performance, an independent specimens and a reinforced concrete column were fabricated to conduct a seismic performance test. As a result of loading test of the independent specimens, the strength was increased compared to the steel tube column without internal filling, and the ductility ratio did not significantly increase due to the falling off of the weld. As a result of loading test of the concrete reinforcement specimen, the strength, ductility ratio, and energy dissipation were increased, and the number of cracks by loading step decreased compared to the non-reinforced specimen.

An alternative fabrication method for carburizing steel using spark plasma sintering (SPS) is investigated. The sintered carburized sample, which exhibits surface modification effects such as carburizing, sintered Fe, and sintered Fe–0.8 wt.%C alloys, is fabricated using SPS. X-ray diffraction and micro Vickers tests are employed to confirm the phase and properties. Finite element analysis is performed to evaluate the change in hardness and analyze the carbon content and residual stress of the carburized sample. The change in the hardness of the carburized sample has the same tendency to predict hardness. The difference in hardness between the carburized sample and the predicted value is also discussed. The carburized sample exhibits a compressive residual stress at the surface. These results indicate that the carburized sample experiences a surface modification effect without carburization. Field emission scanning electron microscopy is employed to verify the change in phase. A novel fabrication method for altering the carburization is successfully proposed. We expect this fabrication method to solve the problems associated with carburization.

자기공명영상(MRI) 장비의 조영제로 흔히 사용되는 가돌리늄(Gd)은 매우 안정된 상태로 하수처리과정에서 거의 제거되지 않고 수환경으로 유입된다고 알려져 있다. 따라서 본 연구에서는 세 가지의 공법으로 하수처리를 하는 부산 수영 하수처리장에서 채취한 하수 시료의 공정별 용존 희토류 원소의 제거율 및 수환경으로 배출되는 인위적 기원 Gd (Gdanth)의 배출량을 평가하고자 하였다. 용존 희토류 원소는 공정별 처리 단계에 따라 무거운 희토류 원소(Tb-Lu)에 비 해 가벼운 희토류 원소(La-Eu)에서 농도가 감소하는 경향을 보였다. 또한 일부 시료에서 나타난 음의(negative) Sm anomaly (<1)는 생물학적 제거 과정에서 Sm이 입자나 인산염과 흡착되어 함께 제거되었을 가능성을 시사한다. 모든 시 료에서 양의(positive) Gd anomaly (149±50, n=9)를 보였으며, 공정별로 측정된 Gd의 총 농도 중 Gdanth은 약 97% 이 상을 차지하는 것으로 나타났다. 이는 하수처리과정에서 Gdanth 이 거의 제거되지 않고 수영강 하류로 배출된다는 것을 의미한다. 일별 처리용량을 고려하여 각 공정에서 배출되는 Gdanth의 배출량은 259 mmol/day로 추정할 수 있다. 본 연 구의 결과는 하수처리장을 통해 수영만 연안으로 Gdanth이 지속적으로 배출될 것으로 예상되며, 향후 Gd의 중장기적인 관측이 필요함을 시사한다.

The seismic behaviors of the arch structure vary according to the rise-span ratio of the arch structure. In this study, the rise-span ratio (H/L) of the example arch structure was set to 1/4, 1/6, and 1/8. And the installation angle of the seismic isolator was set to 15°, 30°, 45°, 60° and 90°. The installation angles of the seismic isolator were set by analyzing the horizontal and vertical reaction forces according to the rise-span ratio of the arch structure. Due to the geometrical and dynamic characteristics of the arch structure, the lower the rise-span ratio, the greater the horizontal reaction force of the static load, but the smaller the horizontal reaction force of the dynamic load. And if the seismic isolator is installed in the direction of the resultant force of the reaction forces caused by the seismic load, the horizontal seismic response becomes small. Also, as the installation angle of the seismic isolator increases, the hysteresis behavior of the seismic isolator shows a plastic behavior, and residual deformation appears even after the seismic load is removed. In the design of seismic isolators for seismic response control of large space structures such as arch structures, horizontal and vertical reaction forces should be considered.

2-에티닐-N-노나노일피리디늄 클로라이드를 치환기로 갖는 새로운 폴리아세틸렌 유도체를 합성하였다. 반응초기에 2-에티닐피리딘과 노나노일 클로아이드의 4차염화반응으로 생성된 단량체 종인 2-에티닐-N-노나노일피리디늄 클로라이드 는 별도의 촉매 없이도 중합반응이 잘 진행되었으며, 그결과 89%의 수율로 폴리아세틸렌계 이온성 공액구조 고분자를 합 성할 수 있었다. 여러 가지 분석장비를 이용하여 고분자 구조를 분석한 결과 설계한 치환기를 갖는 폴리아세틸렌 유도체 가 합성되었음을 확인할 수 있었다. 본 고분자는 메탄올, DMF, DMAc, DMSO, NMP 와 같은 극성 용매에 완전히 용해하였 으며, 이온성 측쇄 부분을 갖는 특성으로 다루는 과정에서 공기중 수분을 흡수하는 경향이 강했다. 고분자의 광흡수 및 전 기화학적 특성을 측정하고 분석하였다. 본 고분자는 산화-환원 피크 사이에 비가역적 전기화학적 거동을 보였으며 다른 이 온성 공액구조 고분자의 경우와 유사하게 전기화학적 스캔수를 증가한 실험에서 50회까지도 안정된 산화-환원 거동을 보 였다.

This paper considers the influence of internal heat exchanger and capillary tube on the efficiency of small refrigeration system using eco-friendly refrigerants such as R290, R600a, R1270, and R717. A refrigeration system using such internal heat exchanger and capillary tube may improve performance, but may degrade performance. Therefore, this paper used a mathematical model in a normal state to understand performance characteristics as to what change occurs when internal heat exchanger and capillary tube are attached to eco-friendly refrigerant based on R134a. In addition, the effects of operating conditions such as refrigerant flow rate, evaporation temperature, condensation temperature, subcooling degree internal heat exchanger length and capillary tube length were analyzed. The result showed that the evaporation temperature, condensation temperature, subcooling degree, internal heat exchanger length and capillary tube length had an effect on the refrigeration capacity and compression power. Therefore, it is necessary to design a refrigeration cycle using an eco-friendly refrigerant by grasping these effects in detail.

The precast-buckling restrained braces(PC-BRB) reinforced with engineering plastics that can compensate for the disadvantages in the manufacturing process of the existing buckling restrained brace. In this study, to examine the applicability of PC-BRB to actual structures, example structures similar to school facilities were selected and the reinforcement effect was analyzed analytically according to the damping design procedure of PC-BRB. Load-displacement curve through the incremental loading test appeared similar to the bilinear curve. Applying test result, Analytical model of PC-BRB model was constructed and applied to the example structure. As a result of the analysis, the PC-BRB showed stable hysteresis behavior without lowering the strength, and the inter story drift ratio and the shear force were reduced due to the damping effect. In addition, the reduction ratio of the shear force was similar to the reduction ratio assumed when designing the damping device.

대기오염물질 감축에 대한 국제적인 인식이 높아짐에 따라 친환경 선박에 대한 수요가 증가하고 있어 각국에서 전기추진선박 개발을 활발하게 수행하고 있다. 현재 전기추진선박에 대해서는 주로 전기추진시스템 및 전동기 연구를 주로 수행하고 있으며, 선박 관점 에서 전기추진시스템 및 배터리의 탑재를 고려한 국내 연안 차도선 개념설계 연구는 수행된 바가 없다. 본 연구에서는 배터리 차량 기반의 이동식 전원공급시스템을 주전원으로 하는 순수전기추진차도선의 개념설계 과정에서의 주요 고려사항에 대하여 검토하였다. 100척 이상의 국내 연안차도선의 제원을 분석하여, 요구사항 만족을 위한 선박의 주요제원 선정과 이동식 배터리 차량 탑재를 고려한 비손상, 손상 복원성능 검토를 수행하였고, 개념설계 과정에서 발생하는 문제의 원인분석을 통해 해결방안을 모색하였다.

When an unexpected excessive seismic load is applied to the base isolation of arch structure, the seismic displacement of the base isolation may be very large beyond the limit displacement of base isolation. These excessive displacement of the base isolation causes a large displacement in the upper structure and large displacement of upper structure causes structural damage. Therefore, in order to limit the seismic displacement response of the base isolation, it is necessary to install an additional device such as an anti-uplift device to the base isolation. In this study, the installation direction of the base isolation and the control performance of the base isolation installed anti-uplift device were investigated. The installation direction of the base isolation of the arch structure is determined by considering the horizontal and vertical reaction forces of the arch structure. In addition, the separation distance of the anti-uplift device is determined in consideration of the design displacement of the base isolation and the displacement of the arch structure.