• Korean Journal of Construction Engineering and Management
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• v.19 no.2
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• pp.117-125
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• 2018

The primary objectives of this study are to develop a detail design of automated PHC pile head cutting machine and structural stability analysis of detail design that improves the conventional head cutting work in safety, quality, and productivity. For this, the following research works are conducted sequentially; 1)literature review and field study, 2)expert survey and interview, 3)selection of core technology using AHP analysis, 4)deduction of detail design 5) verification of structural stability. As an outcome, it is analyzed that gripper and gripper bearing shaft are structurally stable. Their maximum stresses are shown as 15.93%, 10.58% compared to their yield strength respectively. The results of detail design and structural stability analysis in this study will be utilized for the actual development of the automated PHC pile cutting machine prototype.

• Journal of Bio-Environment Control
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• v.27 no.2
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• pp.103-110
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• 2018

This study was conducted to investigate the optimum irrigation method for propagation of cutting strawberry ($Fragaria{\times}ananassa$ Duch. cv. Maehyang) plantlet in summer season. The cutting strawberry plantlets were planted in 24-cell tray ($60{\times}34{\times}10cm$) filled with commercial mixed medium (Tosilee) and placed in semi closed-type small plastic tunnel. Each semi closed-type small plastic tunnel was treated as follows; control (non-treatment), over head irrigation (twice a day), capillary mats irrigation (twice a day), or fog irrigation (30 minutes turn on and 10 minutes off from 8:00 to 18:00). The strawberry plantlets were rooted during 8 days in the semi closed-type small plastic tunnel, and then plastic film was removed. Growth parameters, such as plant height, root length, number of primary roots, petiole length, leaf length, leaf width, crown diameter, SPAD, leaf area, fresh and dry weights of the shoot and root, were measured at 61 days after cutting. Relative humidity in tunnel was high in the order by fog irrigation, over head irrigation, capillary mats, and the control as 72.5, 56.3, 45.8, and 29% on average, respectively. However, the air temperature was similar in all treatments. On the 4 and 8 days, the rooting rate of strawberry plantlet was significantly higher in the over head irrigation and fog irrigation treatments. Plant height, petiole length, crown diameter, and leaf area were highest in the over head irrigation and fog irrigation treatments. In addition, fresh and dry weights of shoot were greater in over head irrigation and fog irrigation treatments than the others. Dry weight of root was differed significantly heaviest in the fog irrigation treatment. However, root length, no. of primary roots, SPAD value, and fresh weight of root were not significantly different in all treatments. These results indicated that growth and rooting for propagation of cutting strawberry plantlet 'Maehyang' were best achievement in the over head irrigation and fog irrigation treatments.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.11
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• pp.45-54
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• 2018

The primary objective of this study is to develop a conceptual design of all-in-one attachment based steel pipe pile cutting robot that improves the conventional work in safety, quality, convenience and productivity. For this, the following research works are conducted sequentially; 1)literature review, 2)field investigation, 3)selection of element technology for conceptual design, 4)deduction of conceptual design and its work process, 5)technical feasibility analysis of the conceptual design and its work process. As a result, leveling laser and laser detector, plasma cutter, rotary grapple are selected as core technologies. Futhermore, a conceptual design and work process of an all-in-one attachment based steel pipe pile cutting robot are developed based on the core technologies. According to the technical feasibility analysis result, at least 76.8% of the respondents are selected positive answer about each device of the all-in-one attachment based steel pipe cutting robot. It is expected that the application range and impact on the construction industry will be enormous due to the increasing trend of the steel pipe pile market.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1566-1570
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• 2005

The aspherical lenses are used as optical lens of HMD optical system. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, the diamond tool nose radius, the cutting speed, the feed rate, the depth of cut, and cutting fluid type are found. The demanded surface roughness 10 nm Ra, aspherical form error $1.0\;\mu{m}$ P-V for aspherical lens of optical data storage device are satisfied.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.29-35
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• 2001

The cutting characteristics of Ti-6Al-4V alloy and total wear when machining Ti-6Al-4V alloy was studied to understand the machining characteristics. This material is one of the strong candidate materials present and future aerospace or met ical applications. Nowadays their usage has already been broaden to commercial applications such as golf club head, finger rings and many decorative items. Anticipating the general use of this material and development of the titanium alloy in domestic facilities, the review and the study of the machining parameters far those alloys are deemed necessary. This study is concentrated to the machining parameters of the Ti-6Al-4V alloy due to their dominant position in the production of tita mum alloys.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_3
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• pp.1197-1204
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• 2023

Ti-alloy, a high-strength alloy material among the materials used in aircraft that are trending toward lighter weight, is classified as a difficult-to-cut material that requires a lot of energy for cutting. Cutting in a high-temperature environment is considered one means of making this possible, and various studies have been conducted on it. In particular, research on LAM (Laser Assisted Machining (LAM)), which utilizes laser heating of the cutting area, is being actively conducted. Before processing of the milling cutter begins, the temperature is raised locally by the laser irradiated through the laser head carrier, and the resistance during milling is reduced. Therefore, in this paper, in order to derive such conditions, we performed heat transfer analysis according to transfer conditions and compared it with actually applied test data to use it to establish appropriate processing conditions.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.508-517
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• 2011

The linear cutting test is the most reliable and accurate approach to measuring cutting forces and cutting efficiency using full-size disc cutter in various rock types. The result of linear cutting tests can be used to obtain the key parameters of cutter-head design (i.e. optimum cutter spacing, cutter forces). In Korea, LCM (Linear Cutting Machine) tests have been performed for typical Korean rock types, but these studies focused on the isotropic rocktypes. For prediction of TBM (Tunnel Boring Machine) performances in complex geological conditions including a bedded and schistose rockmass, it is important to consider the effects of anisotropy of rockmass on cutting performances and cutting efficiency. This study discusses a series of LCM tests that were performed for Asan Gneiss having two types of anisotropy angles to assess the effect of the anisotropy angle on rock-cutting performances of TBM. The result shows that the rock-cutting performances and optimum cutting conditions are affected by anisotropy angle and the effect of anisotropy on rock strength should be considered in a prediction of the cutting performances and efficiency of TBM.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.04b
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• pp.6-6
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• 1998

In 1957, the first magnetic disk drive compatible with a movable head was introduced as an external file memory device for computer system. Since then, magnetic disks have been improved by increasing the recording density, which has brought about the development of a high performance thin film magnetic head. The thin film magnetic head has a magnetic circuit on a ceramic substrate using IC technology. The physical property of the substrate material is very important because it influences the tribology of head/disk interface and also manufacturing process of the head. $Al_{2}O_{3}$-TiC ceramics, so called ALTIC, is known to be one of the best substrate materials which satisfies this property requirement. Even though the head is not in direct contact with the disk, frequent instantaneous contacts are unavoidable due to its high rotating speed and the close gap between them. This may cause damage in the magnetic recording media and, thus, it is very important that the magnetic head has a good wear resistance. $Al_{2}O_{3}$-TiC ceramics has an excellent tribological property in head/disk interface. Manufacturing process of thin film head is similar to that of IC, which requires extremely smooth and flat surface of the substrate. The substrate must be readily sliced into the heads without chipping. $Al_{2}O_{3}$-TiC ceramics has excellent machineability and mechanical properties. $Al_{2}O_{3}$-TiC ceramics was first developed at Nippon Tungsten Co. as cutting tool materials in 1968, which was further developed to be used as the substrate materials for thin film head in collaboration with Sumitomo Special Metals Co., Ltd. in 1981. Today, we supply more than 60% of the substrates for thin film head market in the world. In this paper, we would like to present the sintering process of $Al_{2}O_{3}$-TiC ceramics and its property in detail.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.985-993
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• 2006

The use of prefabricated concrete piles have been gradually increased in many construction sites. One of main works for building a concrete pile foundation is to crush a part of pile head which is compressed with more than $800kg/cm^2$. A pile cutting work is usually performed by a crusher and three to four skilled workers. Recent reports on the pile cutting work reveal that a lot of cracks which significantly reduce the strength of the pile and are frequently made during pile cutting operations and it is very repetitive and labor intensive work. To improve productivity, safety, and quality of the conventional concrete pile cutting work, the research on developing an automated concrete pile cutter has been performed. In this paper, sensing methods for detecting a pile cutting line are suggested with operation process algorithms. The suggested methods are very important to develop the automated pile cutter. A pilot-type of the automated pile cutter that adopt one of the suggested sensing methods, is developed and tested in a construction site.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.535-540
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• 2011

It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.