• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2227-2232
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• 2009

Novel polythiol materials of urethane lens series for plastic optical lens were synthesized from polyol materials via thioisouronium of thiourea with c-HCl in refluxing aqueous solution, in which polythiol material was carried out from hydrolysis of thioisouronium by ammonia water. Their structure properties were identified by EA, EI-MS, FT-IR, $^1H\;and\;^{13}C$ NMR spectroscopies and TGA. Their ophthalmic lenses as polythiourethane material were prepared by thermal curing to an injected glass mold using the evenly solutions of diisocyanates series (TDI, XDI, HDI or IPDI) with polythiols. Polythiourethane shows that the strong stretching mode for SH group of polythiol disappeared in FT-IR spectra after thermosetting polymerization. Thermal deformation starting temperature of ophthalmic lenses was determined by TMA. Ophthalmic lenses made from characteristic polythiol and diisocyanate series have transparency, colorless and good impact strength, in which thermal resistance and impact strength of ophthalmic lenses were influenced by diisocyanate series. Physical properties of ophthalmic lens have contrast thermal resistance with impact strength. The property of thermal resistance and impact strength for respective ophthalmic lenses was examined by TMA and drop ball test.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권4호
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• pp.331-342
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• 2011

The transmission of tracked vehicles performs complex functions as steering, shifting, braking, etc. and the system level life time has been a key influenced by the number of sub-parts like as gear assembly, torque converter, clutches, bearings and so on. In particular, the mechanical type steering system in tracked vehicle has impact shock torques in steering shift and those kind of shock torques can effect on the durability of many sub-parts in power train system. The field failure modes of gear assembly, steering assembly and the bearings of output shaft appear as a very complex phenomenon. In this study, the actual failure, which may occur in field, of the transmission was investigated comprehensively and that the endurance test on the resulting output shaft bearing failure analysis and life assessment was performed. Life time test method used in this study, developed for the purpose of the internal usage, and under these testing techniques the impact of the each bearing damage, which used in tracked vehicle transmission left / right outputs of different structures, was analyzed.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.35-41
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• 2011

Recently, board level solder joint reliability performance of IC packages during drop impact becomes a great concern to semiconductor and electronic product manufacturers. The handheld electronic products are prone to being dropped during their useful service life because of their size and weight. The IC packages are susceptible to solder joint failures, induced by a combination of printed circuit board (PCB) bending and mechanical shock during impact. The board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this paper, applying the JEDEC (JESD22-B111) standard present a finite element modeling of the FBGA. The simulation results revealed that maximum stress was located at the outermost solder ball in the PCB or IC package side, which consisted well with the location of crack initiation observed in the failure analysis after drop reliability tests.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.784-789
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• 2001

In order to investigate the fracture behaviors(penetration modes) and the resistance to penetration during ballistic impact of cold-rolled Al 5052 H34 alloy laminates, anodized Al 5052 H34 alloy laminates, and Al 5052 H34 alloy after cold-rolling, ballistic testing was conducted. In general, superior armor material is brittle materials which have a high hardness. Ballistic resistance of these materials was measured by protection ballistic limit(V50), a statical velocity with 50% probability for incomplete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are observed respectfully, resulting from V50 test and Projectile Through Plate(PTP) test at velocities greater than V50. PTP tests were conducted with 0$^{\circ}$obliquity at room temperature using 5.56mm ball projectile. V50 tests with 0$^{\circ}$obliquity at room temperature were also conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface Hardness, resistance to penetration, and penetration modes of Al 5052 H34 alloy laminates compared to those of cold-rolled Al 5052 H34 alloy laminates and anodized Al 5052 H34 alloy laminates anodized Al 5052 H34 alloy after cold-rolling.

• 한국안전학회지
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• 제31권6호
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• pp.6-11
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• 2016

CFRP composite laminates are widely used as structural materials for airplanes, automobile and aerospace vehicles because of their high strength and stiffness. This study aims to examine an effect of curvature on the penetration fracture characteristic of an orthotropic composite laminated shell. For the purpose, we manufactured orthotropic CFRP shell specimen with different curvatures, and conducted a penetration test using an air-gun. Those specimens were prepared to varied curvature radius(${\infty}$, 200mm, 150mm and 100mm)and were stacked to $[O^{\circ}{_3}/90^{\circ}{_3}]_s$. When the specimen is subjected to transverse impact by a steel sphere(${\Phi}10$), the velocity of steel sphere was measured both before and after impact by determining the time for it to pass two ball-screen sensors located a known distance apart. As the curvature increases, the absorption energy and the critical penetration energy increased linearly because the resistance to the bending moment. Patterns of cracks caused by the penetration of CFRP laminated shells included fiber breakage, lamina fracture, matrix crack interlaminar crack and intralaminar crack.

• 한국안전학회지
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• 제7권1호
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• pp.39-45
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• 1992

강구에 의한 횡방향 저속 충격을 받게 되는 복합재의 충격 응력 및 파동 전파에 관한 이론적 및 실험적 연구가 행하여 진다. 이론적 해석을 위해서는 실험적 접촉 법칙과 연계된 Whitney와 Pagano의 이론에 근거한 판 유한 요소 모델이 사용되며, 실험적 해석을 위해서는 직접적인 충격실험이 수행된다. 이러한 해석을 위한 시험편은 ［0/45/0/­45/0］$_{2s}$와 (90/45/90/­45/90)$_{2s}$ 적층 순서를 가지는 유리/에폭시 적층 복합재이며 경계 조건은 clamped-simply support이다. 결과적으로 이러한 두 해석 결과들이 비교 검토되며, 적층 복합재의 충격 응력 및 파동 전파 특성이 규명된다.명된다.

• 한국정밀공학회지
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• 제20권3호
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• pp.178-186
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• 2003

In order to investigate the fracture behaviors (penetration modes) and the resistance to penetration during ballistic impact of Al 5052-H34 alloy laminates, cold-rolled Al 5052-H34 alloy laminates, anodized Al 5052-H34 alloy laminates, and anodized Al 5052-H34 alloy after cold-rolling, a ballistic testing was conducted. In general, superior armor materials are brittle materials which have a high hardness. Ballistic resistance of these materials was measured by a protection ballistic limit (V$_{50}$), a statistical velocity with 50% probability fur incompletete penetration. Fracture begaviors and ballistic tolerance, described by penetration modes, ate observed from the results from the results of V$_{50}$ test and Projectile Through Plates (PTP) test at velocities greater than V$_{50}$, respectively. PTP tests were conducted with 0$_{\circ}$obliquity at room temperature using 5.56mm ball projectile. V$_{50}$ tests with 0$_{\circ}$obliquity at room temperature were concucted with projectiles that could achieve neat or complete penetration during PTP tests. Surface hardness, resistance to penetration, and penetration modes of Al 5052-H34 alloy laminates are compared to those of cold-rolled Al 5052-H34 alloy laminates and anodized Al 5052-H34 alloy laminates and anodized Al 5052-H34 cold-rolled alloy.

• 한국소음진동공학회논문집
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• 제20권7호
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• pp.658-664
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• 2010

A control element drive mechanism(CEDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod containing a neutron absorbing material within a reactor core to control the reactivity of the core. The ball-screw type CEDM for the integral reactor has a spring-damper system to reduce the impact force due to the scram of the CEDM. This paper describes the experimental results to obtain the drop and damping characteristics of the CEDM. The drop tests are performed by using a drop test rig and a facility. A drop time and a displacement after an impact are measured using a LVDT. The influences of the rod weight, the drop height and the flow area of hydraulic damper on the drop and damping behavior are also estimated on the basis of test results. The drop time of the control element is within 4.5s to meet the design requirement, and the maximum displacement is measured as 15.6 mm. It is also found that the damping system using a spring-hydraulic damper plays a good damper role in the CEDM.

• Advances in nano research
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• 제16권2호
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• pp.155-164
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• 2024

The rapid evolution of intelligent sports equipment and gadgets has led to the transformation of smartphones into personalized coaching devices. This transformative role is central in today's technologically advanced landscape, addressing the needs of individuals with contemporary lifestyles. The development of intelligent sports gadgets is geared towards elevating overall quality of life by facilitating sports activities, workouts, and promoting health preservation. This categorization yields two primary types of devices: smart sports devices for exercise and smart health control devices, which encompass functionalities such as blood pressure monitoring and muscle volume measurement. Illustrative examples include smart headbands, smart socks, smart wristbands, and smart shoe soles. Significantly, the global market for smart sports devices has garnered substantial popularity among enthusiasts. Moreover, the integration of sensors within these devices has instigated a revolution in group and professional sports, facilitating the calculation of impact intensity and ball speed. The utilization of various types of smart sports equipment has proliferated, encompassing applications in both sports' performance and health monitoring across diverse demographics. This article conducts an assessment of the application of nanotechnology in the continuous modeling of the magnetic electromechanical sensor integrated within smart shoe soles, with a specific emphasis on its implementation in soccer training. The exploration delves into the nuanced intersection of nanotechnology and sports equipment, elucidating the intricate mechanisms that underlie the transformative impact of these advancements.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.49-55
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• 2011

전자기기에서의 고장 중 대부분은 작동 중 발생하는 열과 충격에 기인한다. 이 열과 충격은 PCB(Printed Board) 부품의 접합부 계면에 균열을 야기 시키고, 이 균열은 금속간 화합물(Intermetallic Compound: IMC)의 형성과 밀접한 관계를 가진다. 본 연구에서는 Sn-Ag-Cu계의 Ag함량을 변화한 Sn-1.0Ag-0.5Cu와 Sn-1.2Ag-0.5Cu 및 Sn-3.0Ag-0.5Cu의 3가지 조성의 솔더로 접합한 소재를 대상으로 1000시간 까지 등온시효(Isothermal Aging) 하였다. 등온시효 동 안 솔더(Solder)의 계면에 발생하는 IMC(Intermetallic Compound) 성장이 관찰되었으며, solder 접합부의 기계적 특성은 굽힘충격 시험법을 이용하여 평가되었다. 그 결과 시효처리 전에는 Ag 함량이 낮은 solder의 굽힘충격 특성이 우수하게 나타났으나, 시효처리 후에는 반대의 결과를 나타내었다. 이 결과는 IMC layer 주변에 생성된 미세한 $Ag_3Sn$ 및 조대한 $Cu_6Sn_5$와 관련되어, 미세한 $Ag_3Sn$이 충격을 완화한 것으로 나타나 이에 따라 굽힘충격 특성에 차이가 나타남을 알 수 있었다.