• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.2 s.314
• /
• pp.39-45
• /
• 2007

This paper presents a novel scheme that quickly searches for the sweet spot of multiple array antennas, and locks on to it for high-speed millimeter wavelength transmissions, when communications to another antenna array are disconnected. The proposed method utilizes a modified genetic algorithm, which selects a superior initial group through preprocessing in order to solve the local solution in agenetic algorithm. TDD (Time Division Duplex) is utilized as the transfer method and data controller for the antenna. Once the initial communication is completed for the specific number of individuals, no longer antenna's data will be transmitted until each station processes GA in order to produce the next generation. After reproduction, individuals of the next generation become the data, and communication between each station is made again. Simulation results of 1:1, 1:2, 1:5 array antennas confirmed the efficiency of the proposed method. The 16bit split is 8bit, but it has similar performance as 16bit gene.

• Tribology and Lubricants
• /
• v.36 no.5
• /
• pp.253-261
• /
• 2020

In this paper, we present an experimental investigation of the frequency characteristics and a visual inspection of an oxidizer pump with a modified rear-floating ring seal for a 7-tonf turbopump. An oxidizer pump typically operates at high rotational speeds and under cryogenic conditions. Despite its low hydraulic efficiency, the floating ring seal is frequently employed as a leakage control solution for turbomachinery because it effectively reduces abrasion by friction. When the oxidizer pump starts up, the floating ring moves excursively but locks up stably against the pump casing when the contact pressure increases. The compressive force on the floating ring depends on the hydrodynamic forces induced by the flow through the floating ring. This force is controlled by the nose position of the floating ring. Based on a validation test for a 7-tonf turbopump with two types of floating rings, we concluded that the floating ring with a small diameter nose can move easily with a low contact pressure in the cooling path. This leads to instability of the pressure fluctuation around the floating ring. In contrast, a floating ring with a large diameter nose has a high contact pressure and attaches strongly to the casing, which causes wear and frictional oxidation between the contact surfaces of the impeller and the floating ring.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.10
• /
• pp.1147-1158
• /
• 2008

In this paper, we designed a phase-looking circuit that locks the 16.8 GHz VTDRO to a 700 MHz SAW oscillator using SPD as a phase detector Direct phase locking with loop filter alone causes the problem of lock time, so VTDRO is phase leered by loop filter with the aid of time varying square wave current generator. The current generator is related to the loop filter and needs the systematic toning. In this paper, a systematic design of the current generator and loop filter is presented. The fabricated PLDRO shows a stabilized frequency of 16.8 GHz, a output power 6.3 dBm, and a phase noise of -101 dBc/Hz at the 100 kHz offset.

• Journal of KIISE:Databases
• /
• v.28 no.3
• /
• pp.458-467
• /
• 2001

Optimistic Two-Phase Locking(O2PL) performs as well as or better than the other approaches because it exploits client caching well and also has relatively lower network bandwidth requirements. However, O2PL leads to unnecessary waits, because, it can not be commit a transaction until the transaction obtains all requested locks. In addition, Optimistic Concurrency Control(OCC) tends to make needless aborts. This paper suggests an efficient optimistic cache consistency protocol that overcomes such shortcomings. Our scheme decides whether to commit or abort a transaction without wait and it adopts transaction re-ordering in order to minimize the abort rate. Our scheme needs only one version for each data item in spite of the re-ordering mechanism used. Finally, this paper presents a simulation-based analysis that shows superiority in performance of out scheme to O2PL and OCC.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.13 no.4
• /
• pp.2471-2478
• /
• 1971

Go Cong Water Control Project was conducted on its preliminary survey and design by Agricultural development Corporation for the Korean Government, an Executing Agency, and Directorate of Irrigation and Rural Engineering of the Ministry of Land Reform, Agriculture and Fishery Development for the Vietnamese Government, a cooperation Agency, under Korean and Vietnamese Economic and Technical Cooperation Program. The main purposes of the project are aimed at the improvements of irrigation and drainage, and salt water prevention of the Go Cong area located at northern part of the Mekong Delta. All the works from field survey through design to preparing reports were carried out by ADC alone and recently Korean Government submitted the relevant reports to vietnamese Government through official channel. The contents of the project are summarized as following: 1. The project comprises irrigation, drainage and salt water prevention facilities on the benefited area of about 55,000 hectares, covering Go Cong and Dinh Tuong(My Tho) Provinces and it will be possible to cultivate rice cropping twice a year, irrigating all the area in the dry season; 2. With completion of this project, annual production of rough rice and vegetables are anticipated to increase by 222,600 .T. and 142,600 M.T. respectively and the internal rateof return stants at 26 per cent, applying for the exchange rate of US $ 1 to VN $ 275. 3. Total investments required for the project are estimated at US $ 56,394,000 of which actual construction cost is estimated at US $ 39,183,000. The project has planned to be d to be developed by four stages, taking bout 7 years. 4. The project needs for three places of pumping plants. 57Km of feed and main irrigation canals, 81Km of drainage channels, 97Km of dike, 23 places of sluices and navigation locks, etc.

• The KIPS Transactions:PartC
• /
• v.13C no.4 s.107
• /
• pp.511-520
• /
• 2006

WebDAV is a protocol which supports web-based distributed authoring and versioning, providing a standard infrastructure for asynchronous collaboration on various contents through the Internet. Current WebDAV-enabled authoring applications that support WebDAV, such as Microsoft office, Photoshop, or Dreamweaver, work by integrating WebDAV capabilities into the application. While this approach provides solid support for collaborative authoring, it has a drawback that each of the applications needs to support WebDAV capabilities in its own way. We developed a WebDAV client named DAView running on Linux KDE, which enables WebDAV-unaware authoring tools to have effective remote authoring capabilities. DAView provides a GUI view of a WebDAV server, similar to existing WebDAV-enabled file managers such as DAVExplorer. Unique among WebDAV file managers, it also provides the ability to launch the authoring application associated to a WebDAV server resource, automatically managing the locks on the resource.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.5
• /
• pp.613-621
• /
• 2019

In the case of door locks most widely used in the market, the most used area as a one-dimensional problem is worn out, and a worn area which does not use a special attack method enables password guessing. To solve this problem, various methods such as a keypad for randomly displaying numbers are introduced, but this is also not completely safe. The common feature of all the solutions so far is that the keypad area is fixed. In this paper, we consider that point in reverse and create a new area smaller than the entire area in the entire area of the keypad, making the keypad of the new area move randomly, thereby preventing the password from being deduced. When using this technique, a new type of keypad is proposed for the first time because of the impossibility of a shoulder surfing attack even though the number of keypad is left as it is.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.6
• /
• pp.115-121
• /
• 2020

With the spread of IoT technology, various IoT applications using facial recognition are emerging. This paper describes the design and implementation of a remote control system using deep learning-based face recognition and hand gesture recognition. In general, an application system using face recognition consists of a part that takes an image in real time from a camera, a part that recognizes a face from the image, and a part that utilizes the recognized result. Raspberry PI, a single board computer that can be mounted anywhere, has been used to shoot images in real time, and face recognition software has been developed using tensorflow's FaceNet model for server computers and hand gesture recognition software using OpenCV. We classified users into three groups: Known users, Danger users, and Unknown users, and designed and implemented an application that opens automatic door locks only for Known users who have passed both face recognition and hand gestures.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.6
• /
• pp.890-896
• /
• 2022

In this paper, gimbal camera control through smart gloves was implemented to increase convenience and accessibility to the control of drones used in various fields. Smart gloves identify human gestures and transmit signals through Bluetooth. The received signal is converted into a signal suitable for the drone through a GCS (Gound Control Station). Signals from smart gloves are expressed in a quaternion method to prevent gimbal locks, but for gimbal cameras, conversion is required to use Roll, Pitch, and Yaw methods. The data conversion mission is performed in the GCS. The GCS transmits an input signal to the control board of the drone through Wi-Fi. The control board generates and outputs the transmitted signal in a PWM manner. The output signal is input to the gimbal camera through the SBUS method and controlled. The input signal of the smart glove averaged 0.093 s and up to 0.099 s to output to the gimbal camera, showing that there was no problem in real-time use.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.6
• /
• pp.7-12
• /
• 2022

This paper introduces the implementation of the AWS IoT service and MQTT based smart home system. The smart home system implemented in this study can monitor temperature and humidity, and can manually adjust the air conditioner heating, and can check the visitors with the camera and remotely control the door lock. The implemented smart home system controls door locks, heating and air conditioners using Arduino, and manages the collected data and control information using the AWS IoT service. In this study, the Android app has been developed to allow users to control IoT devices remotely, and the MQTT protocol was used for data communication and control between the app and the AWS IoT server and Arduino. The implemented smart home system has been implemented based on AWS IoT service, which has scalability to add sensors and devices.