본 연구는 딥러닝을 위한 비선형 변환 접근법을 사용하여 Single-lap joint의 접착 영역을 조사하기 위한 진동 응답 기반 탐지 시스템 을 제시한다. 산업 혹은 공학 분야에서 분해가 쉽지 않은 구조 내에 보이지 않는 부분의 상태와 접착된 구조의 접착 부위 상태를 알기 어려운 문제가 있다. 이러한 문제를 해결하기 위해 본 연구는 비선형 변환을 이용하여 기준 시편의 진동 응답으로 다양한 시편의 접착 면적을 조사하는 탐지 방법을 제안한다. 이 연구에서는 CNN 기반 딥러닝으로 진동 특성을 파악하기 위해 비선형 변환을 적용한 주파 수 응답 함수를 사용했고 분류를 위해 가상의 스펙트로그램을 사용했다. 또한, 제시된 방법을 검증하기 위해 알루미늄, 탄소섬유복합 재 그리고 초고분자량 폴리에틸렌 시편에 대한 진동 실험, 분석적 해, 유한요소해석을 수행했다.

The purpose of this study was to investigate the effects of joint position on the distraction distance in patients with adhesive capsulitis of glenohumeral joint. The study was conducted upon 20 adults in their 40's with the findings of adhesive capsulitis of glenohumeral joint. These subjects were subdivided into 3 groups, which were a group with neutral position(n=7), second group with resting position(n=7) and third group with end-range position( n=6). After having the subject wearing sleeveless shirts exposing armpit and lying straight on the plinth, a physical therapist with OMT qualification pulled glenohumeral joint at the Grade Ⅲ of Kaltenborn-Evjenth traction; and the distance between glenoid fossa and humeral head was measured with ultrasound. Following the application of traction, the group with resting position(.67±0.29) exhibited the longest distance between humeral head and glenoid fossa, and it was followed by neutral position(.50±0.25) and end-range position(.35±.21) in this order. From the comparison of these groups, there was no significant difference in distraction distance between resting position and neutral position; and there was again no significant difference in distraction distance between end-range position and neutral position. However, there was a significant difference in distraction distance between end-range position and resting position(p<.05). Upon application of the Grade Ⅲ of Kaltenborn-Evjenth traction, it was evident that the distance between humeral head and glenoid fossa can be varied depending on the location of the joint.

It has been more than twenty years since the application of GFRP bridge decks in construction fields. Recently, a few studies by governments and individual researchers have investigated in-use GFRP bridge decks. Areas of trouble include the problems of cracking, spalling and the de-bonding of the pavement or the wearing surface on GFRP bridge decks, all of which affect the long-term durability and serviceability of these new construction materials. Related to these problems, reflective cracks on asphalt pavement are directly related to pultruded GFRP bridge decks. This study investigates the behavior of an adhesive joint under weak-axis bending by tests and FE analyses to identify the causes of pavement cracks in in-use pultruded GFRP bridge decks. In detail, the flexural stiffness and the load-carrying capacities in strong and weak axes are measured during bending tests on pultruded GFRP decks. Next, tensile local failures of an epoxy adhesive due to the concentration of deformations at adhesive joints are identified via a weak-axis bending test. Finally, the tensile failure of an epoxy adhesive due to the local concentration of deformation at an adhesive joint under weak-axis bending is verified through a finite element analysis.

본 연구에서는 강재가 맞대기 이음으로 연결될 경우 CFRP(Carbon Fiber Reinforced Plastic) 쉬트(sheet)를 맞대기 이 음부에 접착할 경우 강재 및 CFRP 쉬트에 발생하는 응력을 해석하였다. CFRP 쉬트로 보강한 경우 접착제의 두께, 강재와의 접착 길이, CFRP 강도 변화를 매개변수로 사용하여 이 매개변수에 변화에 따른 이음부의 응력분포를 분 석하였다. 또한 CFRP를 여러 층으로 접착할 경우 각 층의 강도를 다르게 변화시켜 맞대기 이음부에 유리한 응력분 포를 나타내는 CFRP의 강도를 제시하였다. 본 연구를 위해 빠른 수렴성을 가지며 왜곡된 요소형상에서도 정확한 응력결과를 보이는 강화변형률장(Enhanced Assumed Strain Field)을 사용한 평면변형률 유한요소에 대한 프로그램을 작성하였다.

As the performance of microelectronic devices is improved, the use of copper as a heat dissipation member is increasing due to its good thermal conductivity. The high thermal conductivity of copper, however, leads to difficulties in the joining process. Satisfactory bonding with copper is known to be difficult, especially if high shear and peel strengths are desired. The primary reason is that a copper oxide layer develops rapidly and is weakly attached to the base metal under typical conditions. Thus, when a clean copper substrate is bonded, the initial strength of the joint is high, but upon environmental exposure, an oxide layer may develop, which will reduce the durability of the joint. In this study, an epoxy adhesive formulation was investigated to improve the strength and reliability of a copper to copper joint. Epoxy hardeners such as anhydride, dihydrazide, and dicyandiamide and catalysts such as triphenylphosphine and imidazole were added to an epoxy resin mixture of DGEBA and DGEBF. Differential scanning calorimetry (DSC) analyses revealed that the curing temperatures were dependent on the type of hardener rather than on the catalyst, and higher heat of curing resulted in a higher Tg. The reliability of the copper joint against a high temperature and high humidity environment was found to be the lowest in the case of dihydrazide addition. This is attributed to its high water permeability, which led to the formation of a weak boundary layer of copper oxide. It was also found that dicyandiamide provided the highest initial joint strength and reliability while anhydride yielded intermediate performance between dicyandiamide and dihydrazide.