• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.8
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• pp.847-852
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• 2014

As the scaling trend becomes accelerated in process technology for cost reduction in semiconductor chip manufacturing, the requirement for shrink technology has increased. Hot Carrier Injection (HCI) degradation for I/O transistors is most concerning part when shrink. To solve this, the effective channel length (Leff) was increased using liner oxide before Light Doped Drain (LDD) implants and optimized the tilt angle to increase Leff without E-field degradation in LDD region, satisfying the HCI specification.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.6
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• pp.10-21
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• 2010

In the cluster-tree network which covers wide area network and has many nodes for monitoring purpose traffic is concentrated around the sink. There are long transmit delay and high data loss due to the intensive traffic when IEEE 802.15.4 is adapted to the cluster-tree network. In this paper we propose Dynamic Channel Allocation algorithm which dynamically allocates channels to increase the channel usage and the transmission success rate. To evaluate the performance of DCA, we assumed the monitoring network that consists of a cluster-tree in which sensing data is transmitted to the sink. Analysis uses the traffic data which is generated around the sink. As a result, DCA is superior when much traffic is generated. During the experiment assuming the least amount of traffic, IEEE 802.15.4, has the minimum length of active period and 90% data transmission success rate. However DCA maintains 11.8ms of active period length and results in 98.9% data transmission success rate.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1085-1087
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• 1995

A large leakage current may be one of the critical issues for poly-silicon thin film transistors(poly-Si TFTs) for LCD applications. In order to reduce the leakage current of poly-Si TFTs, several offset gated structures have been reported. However, those devices, where the offset length in the source region is not same as that in the drain region, exhibit the asymmetric electrical performances such as the threshold voltage shift and the variation of the subthreshold slope. The different offset length is caused by the additional mask step for the conventional offset structures. Also the self-aligned implantation may not be applicable due to the mis-alignment problem. In this paper, we propose a new fabrication method for poly-Si TFTs with a self-aligned offset gated structure by employing a photo resistor reflow process. Compared with the conventional poly-Si TFTs, the device is consist of two gate electrodes, of which one is the entitled main gate where the gate bias is employed and the other is the entitled subgate which is separate from both sides of the main gate. The poly-Si channel layer below the offset oxide is protected from the injected ion impurities for the source/drain implantation and acts as an offset region of the proposed device. The key feature of our new device is the offset lesion due to the offset oxide. Our experimental results show that the offset region, due to the photo resistor reflow process, has been successfully obtained in order to fabricate the offset gated poly-Si TFTs. The advantages of the proposed device are that the offset length in the source region is the same as that in the drain region because of the self-aligned implantation and the proposed device does not require any additional mask process step.

• Journal of Korea Water Resources Association
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• v.46 no.9
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• pp.947-956
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• 2013

Most of flood protection walls built on the impingement in mountain rivers have been made of concrete. It may cause flood disasters because the smooth wall surface could increase flow velocity. In this study the hydraulic experiments was carried out to evaluate the effect of one side wall with rectangular vertical ribs on flow resistance in open channel. The ratio of the pitch between vertical ribs to its depth, ${\lambda}_{nv}$, was designed so that it include the so-called d type and k type roughness. The range of Froude number, $F_r$, based on hydraulic radius is 0.81~1.12. Flow resistance in the open channel with a rib sidewall depends on the interval length of each ribs and the flow discharge. Maximum flow resistance occurred when ${\lambda}_{nv}$ is 9. In the d type roughness which ${\lambda}_{nv}$ is less than 3, the flow resistance decreases with increase of flow discharge. In the k type roughness which ${\lambda}_{nv}$ is greater than 3, the flow resistance increases with increase of flow discharge. The increments of flow resistance are especially great when ${\lambda}_{nv}$ are 9 and 12. The resistance due to vertical rib is mostly by the shape resistance and the vertical rib on one sidewall of open channel affects on the flow resistance so that the equivalent roughness heights of vertical rib may occur in scale of flow depth. Therefore the vertical ribs may be used to reduce the flow velocity and to move the location of maximum flow velocity from the rib sidewall to the centerward in a cross section of channels.

• Journal of Korea Water Resources Association
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• v.42 no.5
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• pp.397-406
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• 2009

River is able to change by various environmental factors. In order to conduct restoration design of abandoned river channels, it is necessary to evaluate the river through the analysis of past and present river channels. River evaluation requires various data, such as geometry, hydraulic and hydrology, but there is a lot of difficulty to understand topographical information of river change on time and space due to a lack of past data by domestic conditions. This study analyzes the changes in past and present river channels and examines the applicability of river channel evaluation through image analysis using aerial photographs and 1918 year's map. Aerial photograph analysis was conducted by applying the image analysis method and GIS analysis method on Cheongmicheon. As a result of this analysis, we have quantitatively identified the form and size of abandoned channels, changes in the vertical-section and cross-section length of rivers, and micro-landform changes. More importantly, we verified that morphological changes in sandbars due to artificial straightening are important data in identifying the state of current river channels. In these results, although image analysis technique has limitations in two-dimensional information from aerial photographs, we were able to evaluate the changes in river channel morphology after artificial maintenance of the river.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5A
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• pp.473-483
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• 2004

In this paper, we numerically investigated the optimum pump light power best compensating for pulse distortion due to both chromatic dispersion and self phase modulation (SPM) as a function of channel input power in 8 channel ${\times}$ 40 Gbps wavelength division multiplexing (WDM systems. Also we investigated the allowable maximum channel input power dependence on modulation format and fiber dispersion coefficient in the various pump light power of OPC. The considered WDM transmission system is based on path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) compensation method, which has highly-nonlinear dispersion shifted fiber (HNL-SDF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that optimal pump light power of HNL-DSF OPC depend on modulation format, initial channel input power, total transmission length and fiber dispersion. But optimal pump light power of HNL-DSF OPC must be selected to make power conversion ratio to almost unity. And we confirmed that, if we allow a 1 dB eye opening penalty (EOP), the tolerable maximum channel input power is increased by using RZ than NRZ as modulation format when pump light power of HNL-DSF OPC is not optimal value but another values.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.7
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• pp.109-116
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• 1998

In this work was produced and analyzed a z-cut Ti:LiNbO$_{3}$ optical waveguide which applies for various optical devices.A waveguide channel with a thickness 8 .mu.m and a length 66,000.mu.m and a mach-zehnder interferometer type waveguide were fabricated at a diffusion temperature 1050.deg. C for 6-8hours in a wet $O_{2}$ environment. The resulting Ti:LiNbO$_{3}$ optical waveguide was measured to have a Ti-strip thickness of 950.angs. and low loss. Surfaces and cross-sections of a fabricated waveguide were analysed. The mode pattern anaysis revealed that the waveguide showed a single mode at a 1550nm wavelength. The effective dimension of the waveguide was calculated by measuring a gaussian profile; Wx=10.95.mu. and Wy=9.14.mu.m. a propagation loss, of 0.50dB/cm for a TM mode and 0.45dB/cm for a TE mode, was low enough to be accepatable for optical devices.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.297-303
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• 1979

Early morphological changes of Omobranchus slogans (STEINDACHNER) (Family Blennidae) were studied based on the samples of 125 individuals collected from Changseon channel of Nam-hae in June 1973 and May 1979. Descriptions were made with particular emphasis on developmental changes of supraorbital region, fin rays, development of chromatophores and the preopercular spine. In the early stages the lateral profile of the supraorbital region is perpendicular to tile sagittal plane, however, in the later stages it becomes curved. In the early stage of 5.55 mm in total length the number of soft rays of dorsal fin is 18, and that of the anal fin 15. Ventral fin first appears as a premoidal proturberance. It fully developes into a fin composed of two soft rays in the stages of 12.9 mm in total length. The caudal fin rays first appear in the ventral part and in the stages of 6.15 mm in total length it gets one or two soft rays which bear 1-2 segments. In the later stages each ray bears more than 5 segments. Melanophores first appear as two black spots on the central part of the head. They are distributed on the opercle and the antero-dorsal surface of the trunk in the stage of 18mm in total length. At this stage the general chromatophore. pattern is identical to the adult stage. The anal fin bears melanophores at the basal part of the rays, and it is one of the remarkable morphological characters of this species. In early stages the preopercular spine develops reaching the basal part of the pectoral fin. In the later stages of 15 mm in total length relative length of the spine decreases to total length, and ie reaches only the distal margin of the opercular.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.101-112
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• 2013

Large eddy simulation was performed to investigate the effect of linearly increasing wall disturbance on the modification of turbulent characteristics of temperature field in the vicinity of the wall. It was noted that temperature variance increased monotonically whereas temperature dissipation decreased significantly, resulting in a noticeable reduction in both time and length-scales. A sudden drop in turbulent Prandtl number down to around 0.25 in the near-wall region indicated that the similarity between velocity and temperature fields decreases near the wall as a result of linear wall disturbance.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.143-153
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• 2005

Recently, the concern of groynes that provide us with various ecological environment and improvement of scenary near river as well as hydraulic improvement has greatly increased for naturalized river and ecological river restoration. However there is no adequate design guidelines in Korea. Furthermore there is lack of research for installation of groynes in Korea. Thus, in this study, we have conducted hydraulic modeling test for kinds of groyne and changes of permeability and made a study of the analysis for installation factor of groyne. Experimental conditions were the fixed bed model for flow pattern of groyne tip and separation length about changes of groyne length and permeability. The Experiments were conducted to measure velocity and drift angle at groyne tip. The main study kas measured the groyne tip velocity for a factor of scour and drift angle for velocity increase at center of channel. We have suggested the equation about groyne tip velocity rate(tip velocity/ approach velocity) and area rate(groyne area/ flow area). And In recirculation zone of groyne downstream, To study the basic data of groyne about installation interval has analyzed the change of separation length and incidence angle. We have suggested the equation about separation length rate(separation length/ groyne length), changes of permeability and installation angle.