• Journal of the Korean Electrochemical Society
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• v.5 no.3
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• pp.153-158
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• 2002

The effects of leveler on the copper trench filling were investigated during damascene plating process. To investigate the trench filling effect with the addition of a leveler, a cross-section images of the electroplated trenches with the width of$0.37{\mu}m,\;and\;0.18{\mu}m$ were observed by field emission scanning electron microscope (FE-SEM). Polyethylene glycol(PEG), 3-mercapto-1-propanesulfonic acid and Janus Green B were used as a carrier, an accelerator and a leveler. $0.37{\mu}m$ trenches were superfilled without voids, but there was voids formation in $0.18{\mu}m$ trenches when the leveler was not added into the electrolyte. On the other hand $0.18{\mu}m$ trenches were superfilled without voids with the addition of the leveler due to the reduction growth rate of copper at protrusions and edges, which yield smooth final deposit surface. The leverer effect becomes more significant as the width of trenches becomes smaller when trenches are filed.

• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.14-20
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• 2016

Vanadium redox flow battery (VRFB) is an energy conversion device in which charging and discharging are alternatively carried out by oxidation and reduction reactions of vanadium ions with different oxidation states. VRFB consists of electrolyte, electrode, ion-exchange membrane, etc. The role of ion-exchange membranes in VRFB separates anolyte and catholyte and provides a high conductivity to hydrogen ions. Recently much attention has been devoted to develop ideal ion-exchange membranes for VRFB. A number of developed ion-exchange membranes should be evaluated to find out ideal ion-exchange membranes for VRFB. Long-term durability test is a crucial characterization of ion-exchange membranes for commercialization, but is very time-consuming. In this study, the life time prediction protocol of ion-exchange membranes in VRFB cell tests was developed through short-term single cell performance evaluation (real total operation time, 87.5 hrs) at three different current densities. We confirmed a decrease in test time up to 96.2% of real durability tests (expected total operation time, 2,296 hrs) and 5~6% of relative error discrepancy between the predicted and the real life time in a unit cell.

• Journal of architectural history
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• v.20 no.3
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• pp.7-22
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• 2011

With the accumulations of outcomes from archaeological excavations of mountain fortress of three kingdoms period, there have been studies about time-periodic territory range of mountain fortress, difference in the way(method) of construction, defence system and so on from various points of view. This is an empirical study on the construction method of the valley part of stone fortress. First of all, it is required to secure large quantity of fresh water for those who lived at mountain fortress. Especially when builders of fortress construct a fortification at the valley part of stone fortress, in advance they must sufficiently consider several options including the establishment of sustainable water resources. First, when it comes to build a fortification on a ridge[or a slope] of a mountain, you have only to consider a vertical stress. However, when it comes to build a fortification at the valley part of a mountain, You must have more sufficient preparations for the constructing process. Because there are not only a vertical stress but also a horizontal pressure simultaneously. Second, a fortification of mountain fortress built by using unit building stone is a structure of masonry construction like brick construction, and the valley part of it is where the construction of the fortification begins. Third, when it comes to build a fortification at the valley part of a mountain, it seems that they use a temporary method such as coffer dam in oder to prevent the collapse of the fortification due to heavy rain. Furthermore, in response to a horizontal pressure a fortification is built by the way of its plane make an arch, or by piling up the soil with the plate method(類似版築) and earthen wall harder method(敷葉) they increase cross-sectional area of the fortification and its cutoff capacity. In front direction they put the reservoir facility for the fear that the hydraulic pressure and earth pressure are directly transmitted to the fortification. The process of constructing the fortification at the valley part of a mountain is done in the same oder as follows; leveling of ground(整地) ${\Rightarrow}$ construction of coffer dam ${\Rightarrow}$ construction of the fortification between the both banks of the valley ${\Rightarrow}$ construction of the fortification at bottom part of spill way(餘水路) between the both banks of the valley ${\Rightarrow}$ construction of spill way(餘水路) & reservoir facility ${\Rightarrow}$ construction of the fortification at upper part of spill way between the both banks of the valley. Coffer dam facility seems to be not only the protection device on occasion of flood but also an important criterion to measure the proper height of spill way or tailrace(放水路). This study has a meaningful significance in that it empirically examines the method of reduction of the horizontal pressure which the fortification at the valley part of a mountain takes, the date the construction was done, and wether the changes in climate such as heavy rainfall influence the process of construction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.41-48
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• 2008

Enhanced machine reliability has dramatically reduced the rate and number of railway accidents but for further reduction human error should be considered together that accounts for about 20% of the accidents. Therefore, the objective of this study was to suggest a new taxonomy of performance shaping factors (PSFs) that could be utilized to identify the causes of a human error associated with railway accidents. Four categories of human factor, task factor, environment factor, and organization factor and 14 sub-categories of physical state, psychological state, knowledge/experience/ability, information/communication, regulation/procedure, specific character of task, infrastructure, device/MMI, working environment, external environment, education, direction/management, system/atmosphere, and welfare/opportunity along with 131 specific factors was suggested by carefully reviewing 8 representative published taxonomy of Casualty Analysis Methodology for Maritime Operations (CASMET), Cognitive Reliability and Error Analysis Method (CREAM), Human Factors Analysis and Classification System (HFACS), Integrated Safety Investigation Methodology (ISIM), Korea-Human Performance Enhancement System (K-HPES), Rail safety and Standards Board (RSSB), $TapRoot^{(R)}$, and Technique for Retrospective and Predictive Analysis of Cognitive Errors (TRACEr). Then these were applied to the case of the railway accident occurred between Komo and Kyungsan stations in 2003 for verification. Both cause decision chart and why-because tree were developed and modified to aid the analyst to find causal factors from the suggested taxonomy. The taxonomy was well suited so that eight causes were found to explain the driver's error in the accident. The taxonomy of PSFs suggested in this study could cover from latent factors to direct causes of human errors related with railway accidents with systematic categorization.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.211-211
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• 1999

Titanium nitride (TiN) thin films have useful properties including high hardness, good electrical conductivity, high melting point, and chemical inertness. The applications have included wear-resistant hard coatings on machine tools and bearings, decorative coating making use of the golden color, thermal control coatings for widows, and erosion resistant coatings for spacecraft plasma probes. For all these applications as feature sizes shrink and aspect ratios grow, the issue of good step coverage becomes increasingly important. It is therefore essential to manufacture conformal coatings of TiN. The growth of TiN thin films by chemical vapor deposition (CVD) is of great interest for achieving conformal deposition. The most widely used precursor for TiN is TiCl4 and NH3. However, chlorine impurity in the as-grown films and relatively high deposition temperature (>$600^{\circ}C$) are considered major drawbacks from actual device fabrication. To overcome these problems, recently, MOCVD processes including plasma assisted have been suggested. In this study, therefore, we have doposited Ti(C, N) thin films on Si(100) and D2 steel substrates in the temperature range of 150-30$0^{\circ}C$ using tetrakis diethylamido titanium (TDEAT) and titanium isopropoxide (TIP) by pulsed DC plamsa enhanced metal-organic chemical vapor deposition (PEMOCVD) method. Polycrystalline Ti(C, N) thin films were successfully grown on either D2 steel or Si(100) surfaces at temperature as low as 15$0^{\circ}C$. Compositions of the as-grown films were determined with XPS and RBS. From XPS analysis, thin films of Ti(C, N) with low oxygen concentration were obtained. RBS data were also confirmed the changes of stoichiometry and microhardness of our films. Radical formation and ionization behaviors in plasma are analyzed by optical emission spectroscopy (OES) at various pulsed bias and gases conditions. H2 and He+H2 gases are used as carrier gases to compare plasma parameter and the effect of N2 and NH3 gases as reactive gas is also evaluated in reduction of C content of the films. In this study, we fond that He and H2 mixture gas is very effective in enhancing ionization of radicals, especially N resulting is high hardness. The higher hardness of film is obtained to be ca. 1700 HK 0.01 but it depends on gas species and bias voltage. The proper process is evident for H and N2 gas atmosphere and bias voltage of 600V. However, NH3 gas highly reduces formation of CN radical, thereby decreasing C content of Ti(C, N) thin films in a great deal. Compared to PVD TiN films, the Ti(C, N) film grown by PEMOCVD has very good conformability; the step coverage exceeds 85% with an aspect ratio of more than 3.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.3
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• pp.311-326
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• 2013

For providing a basic data concerning with a fishing deck layout design of a trawler the authors conducted the video observations about the working activities of crews on the deck in the different layout of two Korean coastal large stern trawlers (gross tonnage: 139). The winch of the trawler-A was installed on the aft of the fishing deck and the trawler-B, on the forward of the fishing deck. The work and activities of the deck hands on both trawlers were observed using the CCD (charge coupled device) camera installed on each trawler's deck for one month from August 3, 2010. The video data was analyzed by the hierarchical task analysis (HTA) method. In results, numbers of tasks to require deck hands during the hauling net and the casting net were 25 and 28 for the trawler-A and 27 and 48 for the trawler-B, respectively. The working processes were represented a same in both of the trawlers. Location for controlling the deck machineries, the location installed trawl winch, kinds of deck machineries, crew's custom for using deck machineries were the factor affecting to the number of the task. In the case of the improvement suggested in the results is carried out, the reduction percentages of the number of task in the trawler-A and trawler-B were estimated as 24.5% and 51.3%, respectively. Through this study it was found that the quantitative analysis is possible for the work processes, work methods and the work contents in the trawler. Also the suggestion for improving the fishing deck layout design of the trawler was possible by finding out the factors increasing the number of tasks and removing the tasks. We expect that the results of this paper are used as a basic data for designing the layout of deck machineries in the trawler in the future.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.111-121
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• 2012

In this paper, a poly-Si thin film transistor with ${\sim}0.5{\mu}m$ gate length was fabricated and its electrical characteristics are optimized. From the results, it was verified that making active region with larger grain size using low temperature annealing is an efficient way to enhance the subthreshold swing, drain-induced barrier lowering and on-current characteristics. A SONOS flash memory was fabricated using this poly-Si channel process and its performances are analyzed. It was necessary to optimize O/N/O thickness for the reduction of electron back tunneling and the enhancement of its memory operation. The optimized device showed 2.24 V of threshold voltage memory windows which coincided with a well operating flash memory.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.170-178
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• 2008

A high performance object recognition algorithm using Fourier description of the 3D information of the objects is proposed. Object boundaries contain sufficient information for recognition in most of objects. However, it is not well utilized as the key solution of the object recognition since obtaining the accurate boundary information is not easy. Also, object boundaries vary highly depending on the size or orientation of object. The proposed object recognition algorithm is based on 1) the accurate object boundaries extracted from the 3D shape which is obtained by the laser scan device, and 2) reduction of the required database using the size and rotational invariant feature of the Fourier Descriptor. Such Fourier information is compared with the database and the recognition is done by selecting the best matching object. The experiments have been done on the rich database of MPEG 7 Part B.

• Journal of the HCI Society of Korea
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• v.1 no.1
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• pp.21-28
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• 2006

Most of the commercialized wearable text input devices are wrist-worn keyboards that have adopted the minimization method of reducing keys. Generally, a drastic key reduction in order to achieve sufficient wearability increases KSPC(Keystrokes per Character), decreases text entry performance, and requires additional effort to learn a new typing method. We are faced with wearability-usability tradeoff problems in designing a good wearable keyboard. To address this problem, we introduced a new keyboard minimization method of reducing key pitch. From a series of empirical studies, we found the potential of a new method which has a keyboard with a 7mm key pitch, good wearability and social acceptance in terms of physical form factors, and allows users to type 15.0WPM in 3 session trials. However, participants point out that a lack of passive haptic feedback in keying action and visual feedback on users' input deteriorate the text entry performance. We have developed the One-key Keyboard that addresses this problem. The traditional desktop keyboard has one key per character, but the One-key Keyboard has only one key ($70mm{\times}35mm$) on which a 10*5 QWERTY key array is printed. The One-key Keyboard detects the position of the fingertip at the time of the keying event and figures out the character entered. We conducted a text entry performance test comprised of 5 sessions. The participants typed 18.9WPM with a 6.7% error rate over all sessions and achieved up to 24.5WPM. From the experiment's results, the One-key Keyboard was evaluated as a potential text input device for wearable computing, balancing wearability, social acceptance, input speed, and learnability.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.477-482
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• 2010

In a case of multiple posterior teeth loss, antagonistic teeth extrude to the edentulous space and compensatory occlusion on the remained anterior teeth leads to occlusal trauma. Extrusion of antagonistic teeth breaks down occlusion plane and loss of posterior support bring about severe wear of remained teeth. In this situation, it is needed to restore remained teeth and edentulous space by increasing vertical dimension to obtain prosthodontic rehabilitation space and to correct occlusion plane. In this case report, the patient had a masticatory problem with loss of posterior teeth support and an esthetic problem of shortened anterior teeth. Before the tooth preparation for the prosthodontic restoration, the patient used removable device for 2 months to increase vertical dimension reversibly. After that, he got provisional fixed restoration with irreversible tooth reduction and used it for 3 months. It had spent 5 month to evaluate the adaptation state on final restoration with incresed vertical dimension. The increasing amount was 3 mm, which was relatively in less degree and masticatory system adapted to the increased vertical dimension without any pathologic changes. Final restoration was made to have equal-intensity contacts on all teeth in a verifiable centric relations and immediate disclusion of all posterior contacts the moment the mandible moves in any direction from centric relation. In addition, metal occlusion surface on posterior teeth was applied to prevent excessive muscle activation, occlusal trauma and the porcelain fracture.