• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.687-695
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• 2007

Statement of problem: The proper contact relation between adjacent teeth in each arch plays an important role in the stability and maintenance of the integrity of the dental arches. Proximal contact has been defined as the area of a tooth that is in close association, connection, or touch with an adjacent tooth in the same arch. Purpose: The aim of this study was to develop a digital device for measuring the proximal tooth contact tightness by pulling a thin stainless steel strip (2mm wide, 0.03mm thick) inserted between proximal tooth contact. Material and method: This device consists of measuring part, sensor part, motor part and body part. The stainless steel strip was connected to a stain gauge. The strain gauge was designed to convert the frictional force into a compressive force. This compressive force was detected as a electrical signal and the electrical signal was digitalized by a A/D converter. The digital signals were displayed by a micro-processor. The pulling speed was 8mm/s. Results: For testing reliability of the device in vivo, two healthy young adults (A, B) participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of mandible (subject A) and maxilla (subject B) was measured fifteen times for three days at rest. We double-checked the accuracy of the device with a Universal Testing Machine. Output signals from the Universal Testing Machine and the measuring device were compared. Regression analysis showed high linearity between these two signals. In vivo test, no significant differences were found between measurements. Conclusion: This device has shown to he capable of producing reliable and reproducible results in measuring proximal tooth contact. Therefore, it was considered that this device was appropriate to apply clinically.

• The Korean Journal of Mycology
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• v.28 no.2
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• pp.121-122
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• 2000

A destructive collar rot of Doonggulle (Polygonatum odoratum var. pluriflorum) occurred in an experimental farm at Hamyang Medicinal Plant Experiment Station, Kyonguam ARES in 1999. The disease also observed in farmer's fileds in Hamyang and the infection rate reached up to 12.3%. Upper parts of the infected plants were mostly blighted and white mycelial mats were formed on the lesions or soil lines near the stem. The fungus readily formed sclerotia on PDA and then shapes were globoid or irregular, and sized $0.9{\sim}6.8{\times}0.6{\sim}5.2\;mm$ (av. $2.7{\sim}2.3\;mm$). Although the fungus showed wide range of mycelial growth temperature, the optimum temperature was about $30^{\circ}C$. The typical sclerotium type and clamp connections of hyphae were found in the fungus grown in PDA. The causal fungus was identified as Sclerotium rolfsii on the basis of mycological characteristics and pathogenicity that on the host plants. This is the first report on the collar rot of Polygonatum odoratum caused by Sclerotium rolfsii in Korea.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.382-387
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• 2008

Current global construction market has grown at a dramatic expansion rate every year in connection with more market accessibility by foreign contractors. The market openness is largely due to globalization of world construction markets, rapid development of world-wide telecommunication technologies, the formation of collaborative acquisitions and joint ventures among contractors, development of regional Free Trade Blocks, and just name a few. This paper focuses on the formation of collaborative networks when expanding into new foreign markets. The social network analysis (SNA) is introduced to investigate a variety of the collaboration patterns and also their impacts on the performance. To this end, the collaboration cases of 600 international construction projects performed by Korean contractors since 1990 were collected and classified into firm's size, project types, collaboration modes, and performance levels using social network analysis. The results showed a direction in establishing business strategy associated with experienced or inexperienced contractors in international construction projects.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.97-103
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• 2009

Improving TCP performance has long been the focus of many research efforts in 802.11 wireless networks study. Hop count and Round Trip Time (RTT) are the critical sources which serious affect the TCP performance on end to end connection. In this paper, we analytical derived the affection and based on the analysis we propose TCP should Change its Expected Value (TCP-CEV) when hop count and RTT change by setting a reasonable CWND change rate to improve the performance. The proposed scheme is applicable to a wide range of transport protocols using the basic TCP mechanism, and the protocol behavior is analytically tractable. We show that our simple strategy improves TCP performance at least over 12% in a chain topology, 4.9% in a grid topology and improve the TCP convergence.

• Steel and Composite Structures
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• v.27 no.6
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• pp.727-745
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• 2018

The design criteria and the corresponding performance levels characterize the response of extended stiffened end-plate beam-to-column joints. In order to guarantee a ductile behavior, hierarchy criteria should be adopted to enforce the plastic deformations in the ductile components of the joint. However, the effectiveness of thesecriteria can be impaired if the actual resistance of the end-plate material largely differs from the design value due to the potential activation of brittle failure modes of the bolt rows (e.g., occurrence of failure mode 3 in the place of mode 1 per bolt row). Also the number and the position of bolt rows directly affect the joint response. The presence of a bolt row in the center of the connection does not improve the strength of the joint under both gravity, wind and seismic loading, but it can modify the damage pattern of ductile connections, reducing the gap opening between the end-plate and the column face. On the other hand, the presence of a central bolt row can influence the capacity of the joint to resist the catenary actions developing under a column loss scenario, thus improving the joint robustness. Aiming at investigating the influence of these features on both the cyclic behavior and the response under column loss, a wide range of finite element analyses (FEAs) were performed and the main results are described and discussed in this paper.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.37-44
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• 2004

This paper describes a new GaAs-based surface-micromachined microstrip line supported by dielectric post and air-gapped signal line with ground metal. This new type of dielectric-supported air-gapped microstripline(DAML) structure is developed using surface micromachining techniques to provide easy means of airbridge connection between the signal lines and to archive low losses at millimeter-wave frequency band with wide impedance range. Each DAMLs with the length of 5 mm are fabricated and the measured characteristics are compared with those of the conventional microstrip transmission line. These transmission lines are composed of 10 ${\mu}{\textrm}{m}$ height of signal line, post size of 10 ${\mu}{\textrm}{m}$ ${\times}$ 10 ${\mu}{\textrm}{m}$ and post height of 9 ${\mu}{\textrm}{m}$. By elevating the signal lines from the substrate using the micromachining technology, the substrate dielectric loss can be reduced Compared with of the conventional microstrip transmission line showing 7.5 dB/cm loss at 50 GHz, the loss can be reduced to 1.1 dB/cm loss at 50 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.307-314
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• 2010

In this paper, a novel ultra-wideband microstrip-to-suspended stripline(SSL) transition is proposed, and SSL filters with low-loss and high selectivity have been realized using this transition. Since the proposed transition has low-loss and wide bandwidth characteristic, the design procedure of SSL filters become simplified. Additionally, the designed filters do not require extra time-consuming tuning. As design examples, SSL low-pass and high-pass filters have been implemented, and a implemented bandpass filter with connection of the low and high-pass filters performs 2.3~10.5 GHz bandwidth with less than 1.2 dB insertion loss and high selectivity.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.865-874
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• 2002

HTTP (HyperText Transfer Protocol) is a transfer protocol used by the World Wide Web distributed hypermedia system to retrieve the objects. Because HTTP is a connection oriented protocol, it uses TCP (Transmission control Protocol) as a transport layer. But it is known that HTTP interacts with TCP badly. it is discussed about factors affecting the performance or HTTP over TCP, the transaction time obtained by the per-transaction TCP connections for HTTP access and the TCP slow-start overheads, and the transaction time for T-TCP (Transaction TCP) which is one or methods improving the performance or HTTP over TCP. Average waiting time and average turnaround time are important parameters to satisfy QoS (Quality of Service) of end users. Formulas for calculating two parameters are derived. Such formulas can be used for the environment in which each TCP or T-TCP transaction time is same or different. Some experiments and computational experiences indicate that the proposed formulas are well acted, can be applied to the environment which the extension of bandwidth is necessary, and time characteristics of T-TCP are superior to that of TCP. Also, the load distribution method of web server based on the combination of bandwidths is discussed to reduce average waiting time and average turnaround time.

• Journal of the Korea Furniture Society
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• v.19 no.4
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• pp.260-272
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• 2008

The recent concept of kitchen is likely defined as "Kitchen Culture" including the function of living room where all families make a conversation as well as a dinner, and it is becoming another type of the residential environment, deviating from the stereotype as only cooking area. Particularly the comfortableness of living room is closely associated with a receipt function of kitchen, and the sort & dimension & size of furniture and diversity of shapes playa more meaningful role for improving our life standard & comfortableness compared with the past, nevertheless this receipt study is carelessly handled in the first phase of construction. This Study is focusing on understanding the modern concept of kitchen where the open space concept is being introduced as more reasonable space concept, and on suggesting a solution for receipt-function of the modern kitchen concept connected with "L-D-K (Living room - Dining room- Kitchen)" space idea. In the Chapter 2 the concept of receipt and function of kitchen, the wide variety of kitchen utensils was checked up, and in the Chapter 3 the change of trends of kitchen area & receipt space was considered, and finally in the Chapter 4 the modern concept of kitchen was presented, by instancing overseas examples with receipt planning. As a consequence, the alternative of the receipt in the modern kitchen is to install an Ireland table or another type of receipt-available table (lower furniture) in the dead space between kitchen & living room for motivating smooth communication and convenient receipt, and that is the trend nowadays. Kitchen desires a rapid change. Through this kind of study it should be more researched that kitchen is not an independent space any more and lies in the mutual connection of L-D-K.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.440-447
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• 2011

This paper deals with supercapacitor energy storage system for the compensation of the slow response characteristics of a fuel cell generation system for grid connection. A bidirectional dc/dc converter is used for the charging and discharging of the supercapacitor. The conventional converters use additional clamping circuit, etc. to reduce a voltage spike at the instant of switching and to provide wide range of soft switching. The proposed method provides simplified hardware implementation without any clamping circuit, and soft switching condition for both charging and discharging mode with proper switching patterns. The usefulness of the proposed scheme is verified through simulation and experimental results with 1 kW system.