• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.313-318
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• 1999

This study is aim to evaluate of the flexure toughness of fiber reinforced concrete with ring type steel fiber. The experiment proceeding ASTM C 78 is performed to make a comparision between the ring type flber and the double-hook type fiber which is recently come in to use. The size of the test specimen is 10$\times$10$\times$35mm and the flexture test is proceeded by third-point loading method. The test lasts until 2mm deflection and the loading speed is 0.01mm/min by deflection control. From the experimental results, the specimens with ring type fiber of 30kg/㎥ and 30mm diameter of ring circle show much higher toughness indices than those of the double-hook type fiber of 30kg/㎥ and 30mm long.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.581-584
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• 2008

In this study, it is willing to present that fundamental data for proposing quantitatively shrinkage cracking evaluation method such as plat-ring type restrained test method. To examine suitable size of specimen of plat-ring type restrained test method, Evaluated concrete about restrained shrinkage crack properties of numerical analysis of 3D solid element using the MIDAS program, drying shrinkage deformation, restrained shrinkage stress, crack area and crack point with inside ring diameter of specimen in 100mm, 150mm, 200mm and high of Specimen in 30mm, 50mm after curing in condition of constant temperature and usual habit of temperature 20${\pm}$3$^{\circ}$C, humidity 60${\pm}$5%. As a result, it was available about suitable estimation with inside ring diameter of specimen in more than 150mm and high of Specimen in 50mm. Hereafter, it is considered that the study concerning environmental condition and mixing factor in plat-ring type restrained test method is need.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.3
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• pp.197-213
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• 2012

Disc cutter is a key cutting tool for rock excavation by TBMs. This study aimed to characterize the deformation of a cutter ring by strain measurement as well as infrared thermal camera measurement during a series of linear cutting tests for a hard rock. The strain measurement results indicated that the cutter ring clearly showed a linear elastic behavior. The data obtained from the infrared thermal camera measurement demonstrated that the maximum temperature increase in the cutter ring was below $14.4^{\circ}C$. The deformation and temperature increase of the cutter ring during rock cutting were insignificant in a given cutting test condition of this study.

• Tribology and Lubricants
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• v.13 no.4
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• pp.33-39
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• 1997

In order to establish a new temperature criterion to prevent the pistons from ring sticking due to deposit formation, bench test and engine test were performed. The effects of oil degradation and temperature on deposit formation was studied by a modified panel coking test. Oil degradation was analyzed by FTIR. Oil oxidation and nitration were selected as a factors to evaluate oil degradation. Bench test results show that oil oxidation is more effective to the deposit formation than oil nitration. And the temperature increase accelerates deposit formation and deposit formation increase rapidly above 26$0^{\circ}C$. Especially, in case of degraded oil, the deposit formation increases so rapidly that ring sticking can occur. The effect of piston temperature on the deposit formation was confirmed by engine test.

• Transactions of Materials Processing
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• v.17 no.5
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• pp.343-349
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• 2008

The wear between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. This study will discuss characteristics of wear between hard and soft piston ring coatings with running surface of cylinder liner. Detailed tribological analysis by using Pin-on-Disk(POD) testing machine describes the lubricity mechanism between piston ring coatings and cylinder liner at different temperature with and without oil. The effect of surface roughness of the cylinder liner on the friction coefficient and wear amount of piston ring coatings will also be analyzed. To simulate scuffing mechanism between piston ring and cylinder liner, accelerated lab testing was performed. This study will provide the data from tribological testing of hard and soft piston ring coatings against cylinder liner. Furthermore, the microstructures and morphological features of the surface and the near-surface materials during wear will be investigated. From the scuffing test by using POD testing machine, scuffing mechanisms for the soft and hard coating will be analyzed and experimentally confirmed.

• KSTLE International Journal
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• v.6 no.2
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• pp.58-64
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• 2005

An OEM driven working group started in January 2004 to elaborate the philosophies, concepts and test procedures for testing piston ring and cylinder liner materials as well as engine oils outside the engine using the $SRV^{(R)}$ test equipment. The different $SRV^{(R)}$ test philosophies in use by OEMs are compiled. The working group focuses on a.) ASTM sequence VIB (Fuel economy by aging oils), b.) friction and wear in the top dead region under mixed/boundary lubrication, c.) extreme pressure load under mixed/boundary lubrication and d.) hydrodynamic friction. Tribological test result and precision data are presented.

• Journal of the Korean Ceramic Society
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• v.37 no.9
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• pp.856-863
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• 2000

상압 소결법과 통전활성 소결(Plasma Activated Sintering; PAS)법으로 120$0^{\circ}C$부터 150$0^{\circ}C$의 온도범위에서 제조된 지르코니아의 기계적 특성을 ring on ring disk 굽힘시험으로 비교하여 고찰하였다. 모든 소결온도범위에서 PAS법으로 제조된 소결체의 밀도와 경도는 상압 소결법에 의해 제조된 소결체 보다 높게 나타났다. 결정립의 크기는 두 소결법에 의해 제조된 소결체 모두에서 소결온도 증가에 따라 증가하였으나, PAS법으로 제조된 소결체가 상압 소결법으로 제조된 소결체 보다는 결정립 성장이 억제되었다. 파괴인성은 PAS법으로 제조된 소결체의 경우 130$0^{\circ}C$에서 최고값을 나타낸 후 소결온도 증가에 따라 미세하게 감소하였으며, 상압 소결법으로 제조된 소결체의 경우 소결온도 증가에 따라 증가되었다. 소결체의 상분율 변화는 PAS법으로 제조된 경우 전 온도범위 (1200~150$0^{\circ}C$)에서 정방정상만 관찰되었으며, 상압 소결법의 경우 단사정상과 정방정상의 혼합상을 나타내었고, 소결온도 증가에 따라 정방정상의 비율이 증가하였다. 결과적으로 PAS법의 경우 지르코니아의 최적 소결온도는 130$0^{\circ}C$이며, 상압 소결법의 경우 150$0^{\circ}C$임을 알 수 있었으며, 소결체의 파괴인성에 미치는 영향은 결정립 크기 및 정방정상의 분율임을 확인할 수 있었다.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.6
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• pp.337-341
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• 2004

In this paper the effect of chaos induced instability in Brillouin-active fiber-ring sensor is described. The inherent optical feedback by the backscattered Stokes wave in optical fiber leads to instabilities in the form of optical chaos. The paradigm of optical chaos in fiber serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in communication and sensing. At weak power, the nature of the Brillouin instability can occur at before threshold. At strong power, the temporal evolution above threshold is periodic and at higher intensity can become chaotic. The threshold for the Brillouin instability in fiber-ring sensor is much lower than the threshold of the normal Brillouin instability process.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.65-70
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• 2018

Computed tomography system is widely used on various fields because section image of an object can be acquired. During several step to obtain section image, artifacts by many error factors can be added on the image. Ring artifact induced by the CT system is examined in this study. A test phantom of $512{\times}512$ size was constructed numerically, and the ring artifact was investigated by the algebraic reconstruction technique. The computer program was realized using Visual C++ under the fan beam geometry with projections of 720 and detector pixel of 1,280. The generation of ring artifact was verified by applying different detection efficiency on detector pixels. The ring intensity became large as increasing the ring value, and the ring artifacts were strongly emphasized near the center of the reconstructed image. The ring artifact may be eliminated by tracking the position of ring artifact on the reconstructed image and by calibrating the detector pixel.

• Journal of the Korean Society of Safety
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• v.31 no.6
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• pp.25-31
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• 2016

This paper has analyzed the structure, applicable regulations and the resistance characteristics of insulation ring type of CSST (Corrugated Stainless Steel Tubing for Gas). With the flammability test conducted in accordance with KS C IEC 60811-1-1, the evaluation of insulation resistance, temperature characteristics, and reliability has been conducted. An insulation ring type CSST consists of protective coating, tube, nut, insulation ring, packing, socket, and ball valve. Connecting an insulation ring type CSST to gas tubings for gas appliance is not permitted, moreover, the product shall be installed inside a sleeve pipe in case of buried installation such as the ceiling. Damages on protective coating and tube were detected when fire was applied to the test sample with a portable torch for 60 seconds. The insulation resistance of a normal product was $49.59M{\Omega}$, while that of the product completed the flammability test reduced to $9.21M{\Omega}$. The mean insulation resistance within the confidence Interval of 95% using the mini tap program 17 was $49.59M{\Omega}$ and the mean insulation resistance within the confidence interval reduced to $9.21M{\Omega}$. In the normal distribution analysis of 95% confidence interval, the value-P of the normal product was stable at 0.075 and AD(Anderson-Darling) statistic value was turned out to be 0.063, which is very normal, and the standard deviation was analyzed as 0.2586. The value P of the product completed the flammability test resulted in 0.005, the AD was 1.355 and the standard deviation reduced to 0.07908.