• Title/Summary/Keyword: Ground mode

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The micro-tensile bond strength of two-step self-etch adhesive to ground enamel with and without prior acid-etching (산부식 전처리에 따른 2단계 자가부식 접착제의 연마 법랑질에 대한 미세인장결합강도)

  • Kim, You-Lee;Kim, Jee-Hwan;Shim, June-Sung;Kim, Kwang-Mahn;Lee, Keun-Woo
    • The Journal of Korean Academy of Prosthodontics
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    • v.46 no.2
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    • pp.148-156
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    • 2008
  • Statement of problems: Self-etch adhesives exhibit some clinical benefits such as ease of manipulation and reduced technique-sensitivity. Nevertheless, some concern remains regarding the bonding effectiveness of self-etch adhesives to enamel, in particular when so-called 'mild' self-etch adhesives are employed. This study compared the microtensile bond strengths to ground enamel of the two-step self-etch adhesive Clearfil SE Bond (Kuraray) to the three-step etch-and- rinse adhesive Scotchbond Multi-Purpose (3M ESPE) and the one-step self-etch adhesive iBond (Heraeus Kulzer). Purpose: The purpose of this study was to determine the effect of a preceding phosphoric acid conditioning step on the bonding effectiveness of a two-step self-etch adhesive to ground enamel. Material and methods: The two-step self-etch adhesive Clearfil SE Bond non-etch group, Clearfil SE Bond etch group with prior 35% phosphoric acid etching, and the one-step self-etch adhesive iBond group were used as experimental groups. The three-step etch-and-rinse adhesive Scotchbond Multi-Purpose was used as a control group. The facial surfaces of bovine incisors were divided in four equal parts cruciformly, and randomly distributed into each group. The facial surface of each incisor was ground with 800-grit silicon carbide paper. Each adhesive group was applied according to the manufacturer's instructions to ground enamel, after which the surface was built up using Light-Core (Bisco). After storage in distilled water at $37^{\circ}C$ for 1 week, the restored teeth were sectioned into enamel beams approximately 0.8*0.8mm in cross section using a low speed precision diamond saw (TOPMET Metsaw-LS). After storage in distilled water at $37^{\circ}C$ for 1 month, 3 months, microtensile bond strength evaluations were performed using microspecimens. The microtensile bond strength (MPa) was derived by dividing the imposed force (N) at time of fracture by the bond area ($mm^2$). The mode of failure at the interface was determined with a microscope (Microscope-B nocular, Nikon). The data of microtensile bond strength were statistically analyzed using a one-way ANOVA, followed by Least Significant Difference Post Hoc Test at a significance level of 5%. Results: The mean microtensile bond strength after 1 month of storage showed no statistically significant difference between all adhesive groups (P>0.05). After 3 months of storage, adhesion to ground enamel of iBond was not significantly different from Clearfil SE Bond etch (P>>0.05), while Clearfil SE Bond non-etch and Scotchbond Multi-Purpose demonstrated significantly lower bond strengths (P<0.05), with no significant differences between the two adhesives. Conclusion: In this study the microtensile bond strength to ground enamel of two-step self-etch adhesive Clearfil SE Bond was not significantly different from three-step etch-and-rinse adhesive Scotchbond Multi-Purpose, and prior etching with 35% phosphoric acid significantly increased the bonding effectiveness of Clearfil SE Bond to enamel at 3 months.

A Study on the Field Application of Automatic Grouting System (자동화 그라우팅 기법의 현장적용성에 관한 연구)

  • Do, Jongnam;Park, Junghwan;Choi, Dongchan;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.1
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    • pp.63-74
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    • 2012
  • In Korea, grouting has been mostly designed and constructed by experiences without expert knowledge and theoretical study. So there are a lot of problems related to the quality and safty of grouting. Therefor, in this paper the quality management skills and method were discussed through out by using the auto-grouting method and field test of grouting for the construction. Through the limit water injection test of the soil, it make the optimum injection pressure and injection speed of grouting, and through the lugeon test of the rock, it make assess the permeability of before and after grouting. In order to prevent the hydraulic fracture of soil and break away from the grouts if it apply four kinds of mode of grouting stop criteria, injection effects can be improved. From the above characteristcs designers evalute the fitness values of injection pressure(p), injection speed(q) and grouting penetration time(t). So far, to record and manage pressure(p) and speed(q) of grouting autographic devices such as intergation flow-meter usually record data in a roll of paper. Intergration flow-meter can record grouting flow quantity exactly, but the recorded pressures differ from the any basis such as intitial, intermediate and final point. Therefore, it has been argued that is a need of reliable method to describe the connection between the pressure recorded by an intergration flow-meter and the special properties of the grouting target ground. auto-grouting method can describe the reliable connection between the grouting pressure and the special properties of the grouting target ground. So, in this paper by using auto-grouting method, it is expected that to secure basis of quality control techniques construction.

Compensation Analysis of Cell Delay Variation for ATM Transmission in the TDMA Method (TDMA 방식에서 ATM 전송을 위한 셀 지연 변이의 보상 해석)

  • Kim, Jeong-Ho;Choe, Gyeong-Su
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.2
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    • pp.295-304
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    • 1996
  • Toprovide economical BISDN service, with which integration process of many types of media is possible, it is necessary to construct a system with ground network and satellite network combined. The method for this type of transmission using satellite is TDMA that can provide services to many users in various area. However, the most difficult task to connect TDMA which uses synchronous method to ATM which used asynchronous transfer mode is the deterioration n of ATM transmission quality such as cell delay variation. Therefore, it is necessary to develop delay variation compensation method which can confront to the ATM. Efficient ways to use satellite links under the conditions such that maximum efficiency of the delay variation is limited under the required value, and the burst characteristic of transmission cell does not increase are being researched for translation between in ATM and TDMA. This paper points out the problems when time stamp method, reviewd in ground network, is applied to the satellite links to compensate the delay variation .To solve the problem, discrete cell count method is introduced along with the calculation of transmission capacity and error rate.Also, from the observation of stab-ility of the system and verification of reliability even when singal error occurred in the cell transmission timing information, the proposed compensation method appeared to be excellent.

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A numerical study on the 3-Dimensional shape characteristics of small underground cavities (소규모 지하공동 3차원 형상 특성을 반영한 수치해석에 관한 연구)

  • An, Joon-Sang;Kang, Kyung-Nam;Son, Ki-Il;Kim, Woo-Seok;Kim, Byung-Chan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.20 no.5
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    • pp.787-807
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    • 2018
  • When conducting the underground safety impact assessment under the special law in Korea, it is essential to investigate the occurrence of underground cavities. When underground cavities were discovered, the underground safety was assessed through numerical analysis. The previous study has suggested the stability evaluation based on the factor of safety by changing the 2D shape of the small underground cavity. In this study, the effects of small underground cavities considering 3D shapes were examined using a continuum analysis program and compared with the 2D results presented in previous study. If the 3-Dimensional shape of the underground cavity is found close to the sphere type, it would be reasonable to evaluate the factor of safety by the shear strength reduction method regardless of the size and position of the cavity. If a high-aspect ratio underground cavity with a depth of 2 m or more from the ground surface and an aspect ratio (a/b) of 2.0 or more is in the vertical direction, not only the factor of safety but the failure mode shape should be cautions in the stability evaluation using the shear strength reduction method. The results of this study are expected to be basic data on underground safety impact assessment.

Analysis of Vertical Profiles and Optical Characteristics of the Asian Dust Using Ground-based Measurements (지상관측장비를 이용하여 관측한 봄철 황사의 연직분포와 광학적 특성 분석)

  • Lee, Byung-Il;Yoon, Soon-Chang;Kim, Yoonjae
    • Atmosphere
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    • v.18 no.4
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    • pp.287-297
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    • 2008
  • The vertical profiles and optical properties of Asian dust are investigated using ground-based measurements from 1998 to 2002. Vertical profiles of aerosol extinction coefficient are evaluated using MPL (Micro Pulse Lidar) data. Optical parameters such as aerosol optical thickness ($\tau$), ${\AA}ngstr\ddot{o}m$ exponent ($\alpha$), single scattering albedo ($\omega$), refractive index, and volume size distribution are analyzed with sun/sky radiometer data for the same period. We can separate aerosol vertical profiles into three categories. First category named as 'Asian dust case', which aerosol extinction coefficient is larger than $0.15km^{-1}$ and dust layer exists from surface up to 3-4km. Second category named as 'Elevated aerosol case', which aerosol layer exists between 2 and 6km with 1-2.5km thickness, and extinction coefficient is smaller than $0.15km^{-1}$. Third category named as 'Clear sky case', which aerosol extinction coefficient appears smaller than $0.15km^{-1}$. and shows that diurnal variation of background aerosol in urban area. While optical parameters for first category indicate that $\tau$ and $\alpha$ are $0.63{\pm}0.14$, $0.48{\pm}0.19$, respectively. Also, aerosol volume concentration is increased for range of 1 and $4{\mu}m$, in coarse mode. Optical parameters for second category can be separated into two different types. Optical properties of first type are very close to Asian dust cases. Also, dust reports of source region and backward trajectory analyses assure that these type is much related with Asian dust event. However, optical properties of the other type are similar to those of urban aerosol. For clear sky case, $\tau$ is relatively smaller and $\alpha$ is larger compare with other cases. Each case shows distinct characteristics in aerosol optical parameters.

A Study on the Dynamic Amplification Characteristics of the Domestic Seismic Observation Sites using Shear- and Coda-Wave (S파 및 Coda파를 이용한 국내 관측소지반의 동적 증폭특성에 관한 연구)

  • Kim, Jun-Kyoung
    • Tunnel and Underground Space
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    • v.19 no.5
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    • pp.432-439
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    • 2009
  • For more reliable estimation of seismic source, attenuation properties and dynamic ground property, site amplification function should be considered. Among various estimation methods, this study used the Nakamura's method (1989) for estimating site amplification characteristics. This method was originally applied to the surface waves of background noise and therefore there are some limitations in applying to general wave energy. However, recently this method has been extended and applied to the S wave energy successfully. This study applied the method to S wave and Coda wave energy, which is equivalent to the backscattered S wave energy. We used more than 60 observed ground motions from 5 earthquakes which were occurred recently, with magnitude range from 3.6 to 5.1. Each station showed characteristic site amplification property in low-, high- and resonance frequencies. Some of the stations showed as high as 4 times of site amplification in the range of specific frequencies, which may imply abnormal small scale geologic strata below the station or development of various trapped modes in the basin structure. Moreover, removal of site amplification can give us more reliable seismic source and attenuation parameters, addition to the seismic hazard estimation.

Pin Distribute Method of Twist Cable at Military Unmanned Vehicle Wiring Unit Connector (군용 무인 이동체 배선장치 커넥터에서 트위스트 케이블 핀 배치 최적화 방안)

  • Eun, Hee-hyun;Roh, Dong-gyu;Kwak, Gyu-min;Kim, Jae-seung;Lee, Chul
    • Journal of Advanced Navigation Technology
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    • v.24 no.4
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    • pp.245-250
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    • 2020
  • Currently, unmanned military vehicles under development in Korea have more devices to carry out various missions, and interface cables between them are also increasing. In addition, due to a small space problem inside the unmanned vehicle, devices are required to be miniaturized and integrated. For two reasons, connectors also need to be selected, which makes them vulnerable to noise due to the closer distance between the pins. In this paper, we analyzed how much the magnetic field produced by noise at the connector pin where cable twist is released affects the surrounding pin and presented the guide for optimal pin placement. First, the effect of magnetic field is greater than the crosstalk between pin and pin. Second, the magnetic field on both sides between + and - is strong when approaching one step with noise source. Third, the magnetic field strength is improved when setting the ground pin as the ground pin between the noise and the original signal when approaching the A noise source and the two steps. Fourth, in the case of a differential mode communication, the optimal placement area of the sensitive signal was presented according to positions Tx± and Rx±.

Transponder and Ground Station Systems for Drones

  • Kim, Ki-Su;Ha, Heon-Seong;Lee, Jong-Chan
    • Journal of the Korea Society of Computer and Information
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    • v.25 no.6
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    • pp.9-15
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    • 2020
  • In this paper, we propose a case that drone (unmanned aerial vehicle), one of the representative technologies of the 4th Industrial Revolution, threatens airport safety and privacy infringement, and describes a drone control system proposal to solve the problem. Unmanned aerial vehicle (Drone) is creating a serious problem recently, In Korea, on May 21, 19, according to the Jeju Regional Aviation Administration, drones flew over Jeju Jeongseok Airfield twice in the same month, causing problems in aircraft operation. In overseas cases, two drones near the runway of Gatwick International Airport in the UK There has been a disturbance in which the takeoff and landing of the aircraft flies for a while, and various problems have occurred, such as voyeuring the private life of an individual using a drone. This paper is equipped with an Acess Point transponder mounted on a drone (unmanned aerial vehicle), and unspecified many who want to receive flight information (coordinates, altitude, and obstacles) of the drone access the drone AP, receive and receive the flight information of the drone, and receive unspecified multiple Drone AP flight information is collected and collected to provide the information of the drone currently floating on one user interface screen. In addition, an AP transponder is proposed to operate a safe drone (unmanned aerial vehicle) and the drone's flight information is transmitted., To receive and collect and collect data.

Field Test for Estimation of Acting Force on the Drum Cutter Attachment (드럼커터 어태치먼트의 작용력에 대한 현장시험)

  • Soon-Wook, Choi;Chulho, Lee;Tae-Ho, Kang;Soo-Ho, Chang
    • Tunnel and Underground Space
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    • v.32 no.6
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    • pp.373-385
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    • 2022
  • The drum cutter, which is used in the form of an attachment of a excavator, is very useful in that it can be used in connection with a excavator that can perform various tasks in the field. This study estimated the load and torque acting on the drum cutter attachment by measuring the hydraulic pressure and strain that appear during excavation on the exposed rock slope using the drum cutter installed in the excavator. Working conditions such as the operation angle between the boom and arm of the excavator were divided into eight working modes. And as a result of analyzing the variations in hydraulic pressure and action force according to the working mode, it was confirmed that the hydraulic pressure and flow rate can be driven without any problems within the range considered in the manufacturing specifications of the drum cutter. The average load and torque acting on the drum cutter were within the range of the manufacturing specifications, but the maximum load was up to four times the specification. Because sumping was not properly performed due to the high ground strength and the ground included discontinuous surfaces in some locations, no trend of load and torque was found depending on the angle between the boom and arm of the excavator. However, it is believed that this result can be used to determine the range of loads and torques that appear on the drum cutter when excavating a high-intensity rock.

A Study on the Cooking in 'The Kosa-sibi Jip' (2) ("고사십이집(攷事十二集)"의 조리가공에 관한 분석적 연구(2))

  • 김성미
    • Journal of the East Asian Society of Dietary Life
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    • v.4 no.3
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    • pp.1-19
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    • 1994
  • In this paper, twenty-five kinds of food presented in Sooljip(戌集) 5 and 6 of Food collections of 'Kosa-sibi Jip(攷事十二集)' have been classified into four : Staple food, subsidiary food, Tuck(rice cake) and Han-gwa(Korean confectionery), and Tang-jng and tea. Cooking processes have been examined and scientifically analyzed in terms of cooking, Fourteen kinds of Jook (thick gruel with cereal) as well as Urak-Jook were presented among the methods of making Jook, one of staple foods. Milk and ground rice were boiled together into Urak-Jook, which was nutritious because of carbohydrate, added to milk. Hong-sa Myun was mode of ground shrimps, ground bean, ground rice and flour which were kneaded together. It was a nutritiously balanced food. Nineteen kinds of Kimchi presented in this book were classified by the recipes. The five of Jook-soon Ja, U-so Ja, Tam-bok Ja and Jo-gang were made by adding red malt and cereals(boiled rice or candies). Jo-gang, Jo-ga and Jo-gwa-chae were made by adding salt and rice wine. With salt and fermenters added, eight were made. Chim-jup-jeo-ga was made by adding Jang(soy-bean sauce) and the inner chaff of wheat instead of salt. The four of Ka-za-san, Hwang-gwa-san, Tong-gwa-san and Jo-gang were made by adding salt and vinegar. Jo-gang was made by adding salt, rice wine, residue of rice wine and candies. The four of Kae-mal-ga, Ku-cho-chim-chae, Un-gu-hwa and Suk-hwa-chim-chim-chae were made by adding salt and spices. San-got-Kimchi was made without salt. San-got-Kimchi and Suk-hwa-chim-chae were made originally in Korea. Suk-hwa-chim-chae, in particular, was first classified as a kind of Kimchi in this book and oysters were added, which is notable. Pork could be preserved longer when smoked oven the weak fire of thatch ten days and nights. Dog meat was sauced and placed on the bones in a pot. A porcelain was put on the top of the pot. Flour paste sealed the gap between the porcelain and the pot. Some water was poured into the porcelain, and the meat was steamed, with two or three thatched sacks burned, which was a distilled dry steaming. This process has been in use up to now. Various cooking methods of chicken were presented from in Umsik-dimi-bang to in Chosun Musang Sinsik Yori Jebup. These methods were ever present regardless of ages. Such measuring units as Guin(斤) and Nyang(兩) were most frequently used in cooking processes of this book, except in case of Jang(soy bean sauce), vinegar and liquor. Twenty eight kinds of kitchenware and cookers were used, of which porcelains wee most used and pans and sieves followed. The scientific eight cooking methods were as follows. First, salt was refined through saturated solution. Next, it was recommended Hong-sa Myun containing shrimps should not be taken along with pork, which is thought to be a proper diet in terms of cholesterol contained by shrimps and pork. Third, meat was coated with thin gruel and quickly roasted and cleared of the dried gruel membrane, which prevented nutrients from exuding and helped to make the meat well-done. Fourth, The fruit of paper mulberry trees has the protease which can soften meat. Therefore when meat was boiled with th fruit of paper mulberry trees, it can be softened easily. Fifth, pork was smoked over the weak fire of thatch. Sixth, in cooking dog meat, distilled dry steaming raised the boiling point and made it possible to preserve meat longer. Seventh, in boiling the sole of a bear, lime was added, which made meat tender by making the pH lower or higher than that of raw meat. Finally, in boiling down rice gluten, a porcelain in the pot prevented boiling over the brim, which is applied to pots in which to boil medical herbs.

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