Current petrochemical product mainly comes from light olefin, such as ethylene and propylene. these olefins can be obtained as mixture form of olefin/paraffin, which is co-product of naphtha cracking process. However, the mixture of light olefin and paraffin is considerably difficult to separate because they have similar physicochemical properties such as density, boiling point, and molecular weight. Cryogenic distillation is currently utilized, but still suffered from high operating cost. Membrane separation with polyimide-based material is a promising alternative due to its lower energy cost and modular operation. Here, we synthesized composite membrane with metal-organic framework (MOF) based on polyimide exhibiting high permeability and selectivity in propylene/propane separation, as well as simple preparation and high stability.

We synthesized the poly(4-vinylbenzyltributylammonium hexanesulfonate) P[VBTBA][HS] which was obtained via anion exchange with hexanesulfonate after acquiring monomer [VBTBA][Cl] by Menshutkin reaction to investigate its feasibility as draw solute for forward osmosis process. P[VBTBA][HS] shows lower critical solution temperature (LCST) property at about 21℃, while LCST property of [VBTBA][Cl] and P[VBTBA][Cl] was not confirmed. This result suggests that P[VBTBA][HS] can be recovered from solution by heating them to above LCST. In AL-FS mode with solution of 20 wt% P[VBTBA][HS] at 15℃, water flux and reverse solute flux were found to be about 6.43 LMH and 0.59 gMH. This study can provide an understanding of new way of proceeding draw solute and information for the potential design and synthesis of thermo-responsive organic material.

Laminated graphene oxide (GO) membrane has great attention for ultrafast flux membrane with well-defined pore structure. However, laminated structure is sensitive to various factors such as functionalization, fabrication method and especially support morphology due to ultrathin thickness. Herein, we investigated surface roughness effect by controlling systematically wrinkled structure of support with ion beam treatment. Wrinkled surface of support generates free volume at interface, facilitating fast water transport, which confirmed 6.4 times enhancement on permeation of water while maintaining high rejection of all dye molecules. The tunability of nanostructure through support control can provide development for ultrathin GO membrane in water purification.

Perfluorinated sulfonic acid (PFSA) ionomers have been widely used as representative polymer electrolyte membrane (PEM) materials for water electrolysis to generate hydrogen and oxygen gases with a high purity (e.g., 99.999%) simultaneously. PEM should satisfy high selectivity of proton to water and act as gas barrier to hydrogen and oxygen in order to improve current efficiency which is a barometer to determine how effectively the electric energy is used for water electrolysis. In this study, PFSA ionomers with different chemical architectures and equivalent weights were used to make PEM materials for water electrolysis. The structure-property-performance relationship was systematically investigated.

The size of the camping trailer will bring the area of the camping trailer more space. The various types of expandable RV or camping trailers are available to ensure a wider camping space. In this study, we aim to provide technology to produce new types of products. This will ensure a wide range of camping space while, also, facilitating mobile traction, which includes the development of functional, convenience, and aesthetic product design. This will satisfy a wide range of consumer and their diverse needs. As a result, the body weight of less than 500 kg was achieved by weight in the design and manufacturing process of the product. Consumers will be satisfied because they can obtain an abundant amount of camping space.

Light weighting is one of techniques considered importantly at designing the mechanical structure using the light weight material. This study deals with aluminum-6061 and aluminum foam which stood in the spotlight of light weight material. And the finite element method for safety evaluation has been carried out in order to prevent from the damage and fatigue fracture due to crack appearing at the mechanical structure with this material. The simulation analysis as MT(middle tension) test was carried out by using the core of aluminum foam and the material laminated with sandwich structure of Al-6061. The mechanical structure is linked together with various parts and designed as the material with hole or crack. So, MT test is one of the test methods to evaluate the fatigue fracture characteristic of material and the strength inside material with the center crack by applying the load to the part connected pin. The real material strength is thought to be evaluated through the study result of MT test analysis.

The improvement in computing systems and sensor technologies devotes to conduct data-driven structural health monitoring algorithms for existing civil infrastructures. Despite of the development of techniques, the uncertainty oriented from the measurement results in the discrepancy to the actual structural parameters and let engineers or decision makers hesitate to adopt such techniques. Many studies have shown that the modal identification results can be affected by the uncertainties due to the applied methods and the types of loading. This paper aims to compare the performance of modal identification methods using Structural Modal Identification Toolsuite (SMIT) which has been developed to facilitate multiple identification methods with a user-friendly designed platform. The data fed into SMIT processes three stages for the comprehensive identification including preprocessing, eigenvalue estimation, and post-processing. The seismic and white noise response for shear frame model was obtained from numerical simulation. The identified modal parameters is compared to the actual modal parameters. In order to improve the quality of coherence in identified modal parameters, several hurdles including modal phase collinearity and extended modal amplitude coherence were introduced. Numerical simulation conducted on the 5 dof shear frame model were used to validate the effectiveness of using these parameters.

Owing to the development in information and communications technologies have improved the technology for high-speed transmission of massive data, which has changed closed-circuit television (CCTV) video transmission technology. In particular, digitization of the CCTV video format and streaming technology has made it possible to minimize transmission loss and integrate video transmission and camera control(pan/tilt). It has also become possible to provide additional services like remote emergency warning broadcasting with just Internet Protocol (IP). However, because of the structural problems of IP, these changes have also brought about the threat of hacking of CCTV monitoring systems. In this study, we propose a methode to optimize network management by examining cases of enhancement of operational efficiency and security by improving the structure of CCTV monitoring network.

산림천이는 몇 단계의 산림생태계 변화과정을 거쳐 최종단계인 극상림에 도달하는 것으로 우리나라 온대림의 극상림 을 이루는 대표 수종이 서어나무라고 하는 많은 연구결과가 제시되어 왔다. 특정지역 또는 국지적으로 나타나는 서어나무의 상관 군락을 대상으로 식생구조와 천이과정의 연구가 주를 이루고 있고 우리나라 온대림의 극상림으로서 서어나 무림을 제시한다는 것은 논란이 있을 수 있다. 따라서 본 연구는 2014년부터 2017년까지 17개산 75개소의 서어나무림을 대상으로 식생유형과 층위구조를 파악하고 이에 따른 생태적 천이경향을 구명하고자 수행되었다. 유형분류는 식물 사회학적 방법에 따라 수행하였으며 층위구조는 중요치를 분석하여 파악하였다. 종조성에 따른 유형분류결과, 총 6개의 식생단위와 9개의 종군 유형으로 분류되었다. 서어나무군락군은 난티나무군락, 개암나무군락(갈참나무군, 개암나무전 형군), 철쭉군락(물들메나무군, 개서어나무군, 철쭉전형군)으로 분류되었다. 각 층위별로 중요치를 분석하여 서어나무 림의 천이경향을 예측해 본 결과, 서어나무림은 ① 당분간 서어나무림으로 유지되는 유형(식생단위 2, 3, 6), ② 까치박 달림으로 천이가 진행되는 유형(식생단위 1, 4), ③ 붉가시나무림으로 천이가 진행되는 유형(식생단위 5)의 총 3가지 천이유형으로 나타났다.

In this paper, comparative analysis of the 9.12 Gyeongju and 11.15 Pohang earthquakes was conducted in order to provide probable explanations and reasons for the damage observed in the 11.15 Pohang earthquake from both earthquake and structural engineering perspectives. The damage potentials like Arias intensity, effective peak ground acceleration, etc observed in the 11.15 Pohang earthquake were generally weaker than those of the 9.12 Gyeongju earthquake. However, in contrast to the high-frequency dominant nature of the 9.12 Gyeongju earthquake records, the spectral power of PHA2 record observed in the soft soil site was highly concentrated around 2Hz. The base shear around 2 Hz frequency was as high as 40% building weight. This frequency band is very close to the fundamental frequency of the piloti-type buildings severely damaged in the northern part of Pohang. Unfortunately, in addition to inherent vertical irregularity, most of the damaged piloti-type buildings had plan irregularity as well and were non-seismic. All these contributed to the fatal damage. Inelastic dynamic analysis indicated that PHA2 record demands system ductility capacity of 3.5 for a structure with a fundamental period of 0.5 sec and yield base shear strength of 10% building weight. The system ductility level of 3.5 seems very difficult to be achievable in non-seismic brittle piloti-type buildings. The soil profile of the PHA2 site was inversely estimated based on deconvolution technique and trial-error procedure with utilizing available records measured at several rock sites during the 11.15 Pohang earthquake. The soil profile estimated was very typical of soil class D, implying significant soil amplification in the 11.15 Pohang earthquake. The 11.15 Pohang earthquake gave us the expensive lesson that near-collapse damage to irregular and brittle buildings is highly possible when soil is soft and epicenter is close, although the earthquake magnitude is just minor to moderate (M 5+).

V-Coupling is used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger. The back plate is located between the turbine housing and the bearing housing, which is compressed by the bolt clamping force of coupling to prevent gas leakage under turbocharger operation. This paper presents the theoretical and analytical methods to predict the sealing performance by calculating the contact pressures on the back plate. The mathematical model was constructed to derive the contact force on the back plate by considering the force transfer mechanism. And, finite element analysis was carried out to predict the contact pressures by applying the bolt load in the coupling system. As a result, the analysis results of the mathematical model are well consistent with the results of the finite element analysis. Therefore, in the early design stage of turbocharger coupling, mathematical model would be helpful to determine the design parameters.

The TRM method applied in this study is a method aiming at long span and low girder hight of the temporary bridge. When the preload is introduced to the girder member and the preload is removed after by welding the stiffener, a prestress is introduced through the stiffener to increase the load capacity of the member. Therefore, in this study, the structural performance improvement through the application of the TRM method was verified experimentally by the bending tests of the specimens with and without the TRM method.

A study has been conducted on the structural analysis to reduce the light weight of the electric vehicle rotor shaft. ANSYS Static Structural was used for structural analysis. For weight reduction, the solid shaft was converted into a hollow shaft. The yield strength of the existing material SCM 440 is 655MPa, but to increase its safety, the yield strength is changed to 1,030MPa with SCM822H. At this time, weight reduction of about 47% was achieved. The resonance frequency of the rotor shaft was determined by vibration analysis and the structural safety was analyzed.

In this study, finite element (FE) analysis was performed to evaluate the seismic performance of the water treatment plant, which is a major state of the art water treatment plant, to predict tensile cracks and compressive failure. The FE model simulation for two facilities of the water purification plant was made considering the initial conditions, boundary conditions and water effect. For the nonlinear dynamic analysis, seismic analysis was performed using ground acceleration. Tensile cracks and compressive failure are analyzed and the effects on the structures are analyzed. As a result of the analysis, tensile cracks can be predicted to occur in the main structure.

독특한 경관특성과 높은 보존적 가치에도 불구하고, 사구와 관련된 곤충 다양성 연구는 매우 부족한 편이다. 따라서 본 연구에서는 태안해안국립공원에서 주로 관찰되는 사구와 방풍림(해송)에서 서식하는 지표성 딱정벌레류 군집 구조에 대한 비교 연구를 수행하였다. 2014년 6월 중순부터 10월 중순까지 함정트랩을 이용하여 방풍림 5개 지점과 사구 3개 지점을 조사하였다. 조사 결과, 총 2,335개체의 지표성 딱정벌레류를 채집하였으며, 이들은 15속 30종으로 동정되었다. 사구에서는 24종이 채집되었는데, 둥근칠납작먼지벌레(158개체)와 등빨간먼지벌레(153개체)가 우점하였다. 반 면, 방품림에서는 14종이 채집되었고, 둥근칠납작먼지벌레(1,630개체), 윤납작먼지벌레(130개체) 및 붉은칠납작먼지벌 레(42개체)가 우점하였다. 방풍림과 사구의 지표성 딱정벌레류 종 구성의 유사도는 27.4%로 낮았다. 본 연구 결과는 태안해안국립공원에서 발견되는 사구 지형이 방풍림과 비교해서 다른 곤충 군집을 보유하고 있음을 보여주고 있으며, 이는 향후 곤충 보전을 위한 중요한 정보가 될 것이다.

The probabilistic seismic safety assessment is one of the methodology to evaluate the seismic safety of the nuclear power plants. The site characteristics of the nuclear power plant should be reflected when evaluating the seismic safety of the nuclear power plant. The Korea seismic characteristics are strong in high frequency region and may be different from NRC Regulatory Guide 1.60, which is the design spectrum of nuclear power plants. In this study, seismic response of a nuclear power plant structure by Pohang earthquake (2017.11.15. (KST)) is investigated. The Pohang earthquake measured at the Cheongsong seismic observation station (CHS) is scaled to the peak ground acceleration (PGA) of 0.2 g and the seismic acceleration time history curve corresponding to the design spectrum is created. A nuclear power plant of the containment building and the auxiliary buildings are modeled using OPENSEES to analyze the seismic response of the Pohang earthquake. The seismic behavior of the nuclear power plant due to the Pohang earthquake is investigated. And the seismic performances of the equipment of a nuclear power plant are evaluated by the HCLPF. As a result, the seismic safety evaluation of nuclear power plants should be evaluated based on site-specific characteristics of nuclear power plants.