• Journal of the Korean Society of Manufacturing Process Engineers
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• 제16권3호
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• pp.45-53
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• 2017

Disc harrow-type composite working implements of tractors are able to work almost 15km/hr. Soil reversing and plowing of agricultural fields are thereby faster than the existing rotavator speed of 2.5 km/h. In Korea, its supply process is being delayed because of the traditional tillage method of rotavator plowing operations. To develop products suitable for the domestic environment, an analysis and inspection was performed on the products of advanced specifications. 3D modeling was performed on main parts and frames using 3D scanner.

• Transactions of the Korean Society of Automotive Engineers
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• 제4권4호
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• pp.46-57
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• 1996

The direct injection stratified charge(DISC) engine enhances the fuel tolerance and the antiknock tendency. This enhanc3d antiknock tendency allows use of a higher compression ratio which results in higher thermal efficiency. But its actual utilization is prevented by high emission combustion time and wall quenching will be the main causes of increasing unburned hydrocarbons in DISC system. In order to solve this problem, small aount of hydrogen was added to the charging air or injected fuel. The effects of hydrogen addition were examined experimentally by radial fuel injection using a pancake-type constant volume bomb. In case of the hydrogen addition to the charge of air, the combustion the amount of hydrogen. In case of the hydrogen addition to the fuel, the combustion pressure was significantly increased.

• Journal of the Semiconductor & Display Technology
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• 제16권3호
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• pp.25-30
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• 2017

Arago's disk system consists of a speed controller of the DC motor (inner loop controller) and a position controller of the magnetic bar angle (main controller), which are implemented by the design of the PI and PID controller, respectively. First, we analyzed the nonlinear characteristics of the Arago disk system and found the operating point range of three locations as a result. In this paper, a gain scheduler method was applied to guarantee a constant control performance in the range of $0{\sim}130^{\circ}C$, and a structure to change the controller according to the control reference value based on the previously obtained operating points was experimentally implemented. The Distributed Control Systems (DCS) configuration using the Controller Area Network (CAN) was used to verify the proposed method by improving the operational efficiency of the entire experimental system. So, simplicity of the circuit and easy diagnosis were achieved through a single CAN bus communication.

• Journal of the Korea Institute of Building Construction
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• 제9권1호
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• pp.103-109
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• 2009

Strong winds according to global warming cause the increase of the frequency and the repair cost of damaged roofs. In the United States, Factory Mutual Insurance Company(FMIC) promotes the roofing design that resists heavy wind-load, as the means of strict criteria. This fact reveals that more durable roofing system will be also required in Korea. Therefore, this study aims at developing such a system with high wind-resistance performance using Thermoplastic polyolefin(TPO) and Electromagnetic induction technology(EIT) than the previous systems. The system presented in this study consists of 4 main devices as follow; 1) a disc to fix sheets for TPO & EIT method, which can conduct structural design according to site condition, such as region, building height, and wind load. 2) a nail to have about 30% stronger lifting-up capacity than that of the previous nail. 3) a disc to fix sheets, which has triangle protuberance not to damage sheets in the repeatable wind load, and 4) a electromagnetic induction device to combine a disc and a sheet by heating uniformly and quickly adhesive agent on the disc. The results of mock-up test illustrate that the system provides wind-resistant performance to achieve satisfactorily the structural design criteria of FMIC. In addition, the system is faster, chipper, and easier than the existing system, and is expected that this roofing system can be applied to the rehabilitations of an existing as well as a new building.

• Journal of Korean Neurosurgical Society
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• 제64권1호
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• pp.69-77
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• 2021

Objective : Classification systems for cervical ossification of the posterior longitudinal ligament (OPLL) have traditionally focused on the morphological characteristics of ossification. Although the classification describes many clinical features associated with the shape of the ossification, including the concept of spondylosis seems necessary because of the similarity in age distribution. Methods : Patients diagnosed with OPLL who presented with increase signal intensity (ISI) on magnetic resonance imaging were surgically treated in our department. The patients were divided into two groups (pure versus degenerative) according to the presence of disc degeneration. Results : Of 141 patients enrolled in this study, more than half (61%) were classified into the degenerative group. The pure group showed a profound male predominance, early presentation of myelopathy, and a different predilection for ISI compared to the degenerative group. The mean canal compromise ratio (CC) of the ISI was 47% in the degenerative group versus 61% in the pure group (p<0.0000). On the contrary, the global and segment motions were significantly larger in the degenerative group (p<0.0000 and p=0.003, respectively). The canal diameters and global angles did not differ between groups. Conclusion : Classifying cervical OPLL based on the presence of combined disc degeneration is beneficial for understanding the disorder's behavior. CC appears to be the main factor in the development of myelopathy in the pure group, whereas additional dynamic factors appear to affect its development in the degenerative group.

• Journal of Korean Neurosurgical Society
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• 제29권2호
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• pp.180-187
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• 2000

Objective : A number of evidence have suggested a pivotal role of matrix metalloproteinases(MMP) on the degeneration of intervertebral disc. Proteins of intervertebral disc mainly consist of collagen and proteoglycan. These proteins can be destructed by MMP, resulting in changes of main collagen type and degeneration of matrix proteins. The present study was to determine the different effects of MMP-1 and MMP-2 on the degenerative spinal diseases, resulting from aging process. Clinical Materials & Methods : Thirty-one patients were randomly selected among 350 patients whose discs were resected during operation from March 1997 to February 1999. Patients were divided into two groups: group I with spinal stenosis and group II with herniated intervertebral disc. Group II was subdivided into the ruptured(Group Iia) and unruptured(Group Iib). Increases in MMP-1 immunopositive cells were observed in both groups, as evidenced by immunocytochemical staining. However, in marked contrast, the number of MMP-2 immunopositive cells were only seen in group II. There was no significant difference between Group IIa and Group IIb. The MMP-2 immunopositive cells were increased in the anulus fibrosus of ruptured(Group Iia) more than unruptured(Group Iib), but statistically it was not significant. In addition, the immunopositivity of MMP-1 and MMP-2 was proportional to patients's age. Conclusion : These results strongly suggests the possible involvement of MMP-2, but not MMP-1 in progressive herniated intervertevral disc.

• Bulletin of the Korean Mathematical Society
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• 제47권6호
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• pp.1213-1224
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• 2010

Using Ahlfors' covering surface method, some properties on the strong Borel direction of algebroid function of finite order are obtained. The main object of this paper is to prove existence theorem of a strong Borel direction and the existence of filling discs in such direction which briefly extends some results of meromorphic function.

• Communications of the Korean Mathematical Society
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• 제37권3호
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• pp.723-734
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• 2022

In this work, we introduce a new subclass of analytic functions of complex order involving the (p, q)-derivative operator defined in the open unit disc. For this class, several Fekete-Szegö type coefficient inequalities are derived. We obtain the results of Srivastava et al. [22] as consequences of the main theorem in this study.

• Journal of the Health Care and Life Science
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• 제9권1호
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• pp.103-115
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• 2021

The purpose of this study is to understand the annual trend of patients with cervical vertebrae disability and improve their health service utilization in the general description (200 TABLE) of patients with cervical vertebrae disability.The main results of this study are as follows. All patients with cervical vertebrae disability were women aged 50 to 59. Compared to 2010, the proportion of patients with disease increased year by year in all subjects in 2018, with men under 30-39 years of age and women under 19 years of age increasing the highest.

• Tribology and Lubricants
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• 제30권5호
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• pp.295-302
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• 2014

The tribological behavior of an Fe-based bulk amorphous alloy while sliding against a AISI 304 disc is investigated using a unidirectional pin-on-disc type tribometer in dry and distilled water environments. The rod-shaped bulk pins are fabricated by suction casting. The crystallinities of the bulk amorphous alloys before and after the friction tests are determined by X-ray diffraction. The friction coefficient and specific wear rate of the amorphous pin in the water environment are found to be twice and thrice as much as in the dry environment at a low applied pressure, respectively. However, at a higher pressure, the friction coefficient and specific wear rate are 0.4 and 1.02 mg/(Nm/s), respectively, in the water environment. A microstructure analysis shows that the worn surface of the alloy is characterized by delamination from the smooth friction surface, and thus delamination is the main wear mechanism during the friction test in dry sliding environment. In contrast, brittle fracture morphologies are apparent on the friction surface formed in distilled water environment. For the sample tested at a lower sliding speed, the XPS data from the oxide layer are similar to those of the pure element with weak suboxide peaks. For higher sliding speeds, all the main sharp peaks representing the core level binding energies are shifted to the oxide region.