• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.10a
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• pp.56-56
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• 1999

For advanced TFT-LCD manufacturing processes, dry etching of thin-film layers(a-Si, $SiN_x$, SID & gate electrodes, ITO etc.) is increasingly preferred instead of conventional wet etching processes. To dry etch Al gate electrode which is advantageous for reducing propagation delay time of scan signals, high etch rate, slope angle control, and etch uniformity are required. For the Al gate electrode, some metals such as Ti and Nd are added in Al to prevent hillocks during post-annealing processes in addition to gaining low-resistivity($<10u{\Omega}{\cdot}cm$), high performance to heat tolerance and corrosion tolerance of Al thin films. In the case of AI-Nd alloy films, however, low etch rate and poor selectivity over photoresist are remained as a problem. In this study, to enhance the etch rates together with etch uniformity of AI-Nd alloys, magnetized inductively coupled plasma(MICP) have been used instead of conventional ICP and the effects of various magnets and processes conditions have been studied. MICP was consisted of fourteen pairs of permanent magnets arranged along the inside of chamber wall and also a Helmholtz type axial electromagnets was located outside the chamber. Gas combinations of $Cl_2,{\;}BCl_3$, and HBr were used with pressures between 5mTorr and 30mTorr, rf-bias voltages from -50Vto -200V, and inductive powers from 400W to 800W. In the case of $Cl_2/BCl_3$ plasma chemistry, the etch rate of AI-Nd films and etch selectivity over photoresist increased with $BCl_3$ rich etch chemistries for both with and without the magnets. The highest etch rate of $1,000{\AA}/min$, however, could be obtained with the magnets(both the multi-dipole magnets and the electromagnets). Under an optimized electromagnetic strength, etch uniformity of less than 5% also could be obtained under the above conditions.

• Transactions of Materials Processing
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• v.29 no.4
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• pp.194-202
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• 2020

In this paper, experimental and numerical study on a combined sheet metal forming and plate forging of a seal part of a passenger car's hub bearing is conducted to develop the new process of which target is to remove machining process by plate forging and to achieve near-net shape manufacturing. The previous process of a sheet metal forming inevitably needed a machining process for making stepped sheet after conventional sheet metal forming in a progressive way. The stepped sheet is intended to be formed by plate forging in this study. Through the systematic way of developing the combined forming process using solid elements based-elastoplastic finite element method (FEM), several conceptual designs are made and an optimized process design in terms of geometric dimensioning and tolerance of straightness of the thin part is found, which is exposed to bending in metal forming of axisymmetric part. The predicted straightness measured by the slope angle of the tilted thin region is compared with the experimental straightness, showing that they are in a good agreement with each other. Through this study, a systematic approach to optimal process design, based on elastoplastic FEM with solid elements, is established, which will contribute to innovating the conventional small-scaled sheet metal forming processes which can be dealt with by solid elements.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1194-1205
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• 2005

The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to a high pressure common-rail type fuel injection system for the control capability of the high pressure injector's needle and firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector's needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector, both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For the evaluation of the needle response of the above two injectors, we indirectly estimated the needle's behavior with an accelerometer and injection rate measurement employing Bosch's method was conducted. The experimental results show that the spray tip penetrations of piezo­driven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope in piezo-driven injector by altering the induced current.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.265-272
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• 2019

Purpose : Excessive computer use frequently results in musculoskeletal disorders of the neck and shoulder such as forward head posture (FHP). The purpose of this study was to investigate effects of neck and shoulder exercise program on spino-pelvic alignment and the correlation between change in head and neck posture and spino-pelvic alignment in FHP. Methods : The study included 44 participants with FHP. The participants performed the exercise for correction of FHP 2-3 times a week for 4 weeks. We examined whole spine X-ray images in the lateral standing position with both arms crossed. We measured anterior head translation distance (AHT), craniovertebral angle (CVA), cervical lordosis (CL), thoracic kyphosis (TK), lumbosacral lordosis (LSL), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI) of the subjects. The association between change in AHT and each spino-pelvic parameter was also subjected to Pearson's correlation coefficient analysis. Results : There were statistically significant differences before and after exercise in the parameters of AHT, CVA, and SS (p<.05). Significant negative correlation was observed between the change in AHT and CVA (r=-.768, p<.001), and CL (r=-.388, p<.05). There was significant positive correlation between the change in AHT and SS (r=.328, p<.05), and PI (r=.333, p<.05). However, no significant correlation was observed in change in AHT with that of TK, LSL, and PT. Conclusion : Based on the above results, we conclude that there is a relationship between change in AHT, which is a parameter associated with forward displacement of the head, and that of CVA, CL, SS, and PI after exercise in cases of FHP.

• Journal of Korea Water Resources Association
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• v.38 no.3 s.152
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• pp.189-198
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• 2005

This study showed that numerical simulation can be effectively used to analyze discharge capacity according to the form and arrangement of the lock gate of a tidal power plant. For the numerical simulation, FLOW-3D with Reynolds-averaged Navier-Stokes equation as a governing equation was used. This study found that improvement of apron length and approach angle of guide wall of the lock gate causes differences in discharge capacity of $10\%$ or more. In addition, there was a difference of discharge capacity caused by the connecting structures of the drainage gate and hydraulic turbine structure and the side slope at the end of apron. This study also showed that hydraulic investigation to enhance a discharge capacity is needed when the lock gate is designed and that numerical model experiments can be a useful analysis tool to design the drainage structure, as well as the hydraulic model experiment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.5
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• pp.425-433
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• 2012

Dijkstra's algorithm is one of well-known methods to find shortest paths over a network. However, more research on $A^*$ algorithm is necessary to discover the shortest route to a goal point with the heuristic information rather than Dijkstra's algorithm which aims to find a path considering only the shortest distance to any point for an optimal path search. Therefore, in this paper, we compared Dijkstra's algorithm and $A^*$ algorithm for bicycle route selection. For this purpose, the horizontal distance according to slope angle and average speed were calculated based on factors which influence bicycle route selection. And bicycle routes were selected considering the shortest distance or time-dependent shortest path using Dijkstra's or $A^*$ algorithm. The result indicated that the $A^*$ algorithm performs faster than Dijkstra's algorithm on processing time in large study areas. For the future, optimal path selection algorithm can be used for bicycle route plan or a real-time mobile services.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.231-237
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• 2007

The torque ripple of the hydraulic pumps for the Electro-hydrostatic Actuators can disturb the cylinder position control under slewing speed operation condition. In principle, the periodic change of the reaction torque generated by a piston type pump is highly dependent on the waveform of its cylinder chamber pressure. In case of uni-directional pumps operating at constant speed, the transient overshoot and rising slope of the cylinder pressure can be adjusted by the precompression angle and notch shape of their valve plates. Therefore, the influence of the valve plate geometry on the torque ripple magnitude of a bent-axis type piston pump for EHA application was investigated in this study. The results showed that any improvement of the torque ripple of such a bi-directional pump can not be achieved by modifying the valve plate geometry, regardless of its operation speed.

• The Journal of the Korea Contents Association
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• v.13 no.4
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• pp.418-426
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• 2013

This study aims to analyze the formativeness of zzaim (traditional craft techniques to combine two or more materials to make an angle or to weave them to make a slope side) and systematically classified these techniques to help furniture manufacturers effectively utilize them in the design of contemporary furniture. From this data, furniture manufacturers can have benefits to understand which type of zzaim techniques will be appropriate to their plan of building furniture, and practically use relevant techniques in the field. This study classified four different applications of zzaim techniques depending on sites, such as (1) the top, (2) middle body, (3) lower body, and (4) legs of furniture. In summary, zzaim techniques are differently applied depending on the application sites and formative types of furniture. This feature makes general furniture manufacturers who want to apply zzaim techniques for the first time have hard time to understand which kind of technique should be applied to which part. Recognizing this problem, this study expects general manufacturers as well as master artisans to more effectively utilize zzaim techniques by providing the systematic data on the formative analysis of types of furniture and application sites.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.873-884
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• 2013

This study was carried out to establish the conservation plan of specific plants by surveying and analyse the individuals and the environment of habitats on specific plants designated by Juwangsan national park office. The specific plants were 14 species including Berchemia berchemiaefolia, Hylotelephium ussuriense, Aristolochia manshuriensis, Lilium cernuum, Thalictrum coreanum, Exochorda serratifolia, Lilium distichum, Aristolochia contorta, Jeffersonia dubia, Eleutherococcus senticosus, Salix chaenomeloids, Eranthis stellata, Scopolia japonica, and Paeonia japonica. The habitats of specific plants were 40 sites including Berchemia berchemiaefolia of 11 sites, Hylotelephium ussuriense of 8 sites, Lilium cernuum and Thalictrum coreanum of each 3 sites, Exochorda serratifolia of 2 sites, and Lilium distichum, Aristolochia contorta, Jeffersonia dubia, Eleutherococcus senticosus, Salix chaenomeloids, Eranthis stellata, Scopolia japonica and Paeonia japonica of each 1 site. The altitude was the most in 300~400 m. In direction, NW was the most, and it showed SW in that order. The slope angle was the most in 0~10%, and the cliff showed in that order. In the results of species composition by stratum layer, Berchemia berchemiaefolia had the most, 15 species, in tree layer. In shrub and herb layer, this had the most as 20 species and 29 species, too. The species that occupied the largest size was Salix chaenomeloids in 2,500 $m^2$, and Jeffersonia dubia showed 1,500 $m^2$ in that order. The conservation of specific plants is to accomplish the ex situ and in situ conservation at the same time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.681-688
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• 2000

In this paper, a planar antenna that is small and light, is designed and analyzed aiming handset antenna of IMT-2000. Employing the Ensemble simulator based on a MoM, design-parameters are found to determine a resonant frequency. Therefore, it is analyzed with the Ensemble simulation and FDTD numerical for resonating at the allocated frequency for IMT-2000 in the fixed antenna dimension of 21$^{\circ}$wing angle that is a design parameter. Analyzing with FDTD method, Though the results of FDTD are very exact, this analysis introduces errors due to the staircasing approximation in the slope of bowtie. To reduce this error, it is divided to 4-ranges where the cell contains the boundary of perfect conductor/free space. Then, each range is calculated by different by different equation, which modify the H-field to add the component of the area and length of the cell filled with free space. Therefore, the modified FDTD algorithm provided with a narrow bandwidth of return loss calculated with a standard FDTD algorithm that can be extended to the desired ranges.