• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.425-432
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• 2003

The joint treatment of concrete is one of the technical problems in concrete constructions. Joints created with concrete constructions result in serious weakness in the aspects of both structural and water-barrier function. The radar and the infrared thermography method have been used for the non-destructive inspection of several construction joints of concrete structures in this study. The advantages and limitations of these methods are investigated for non-destructive inspection on construction joints of concrete columns. It can be shown that the detecting precision of construction joints using these methods is improved if radar analysis is carried out with a simulation analysis. In case of the infrared thermography method, the shape of construction joints can be also detected when heating is performed before testing. As the result, it has been verified that the construction joints, difficult to be detected by visual inspection, could be inspected effectively in broad areas at short period of time when these two methods are applied.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.4
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• pp.63-75
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• 2016

Aquaculture has historically delivered marine products because the country is surrounded by ocean on three sides. Surveys on production have been conducted recently to systematically manage aquaculture facilities. Based on survey results, pricing controls on marine products has been implemented to stabilize local fishery resources and to ensure minimum income for fishermen. Such surveys on aquaculture facilities depend on manual digitization of aerial photographs each year. These surveys that incorporate manual digitization using high-resolution aerial photographs can accurately evaluate aquaculture with the knowledge of experts, who are aware of each aquaculture facility's characteristics and deployment of those facilities. However, using aerial photographs has monetary and time limitations for monitoring aquaculture resources with different life cycles, and also requires a number of experts. Therefore, in this study, we investigated an automatic prototype system for detecting boundary information and monitoring aquaculture facilities based on satellite images. KOMPSAT-3 (13 Scene), a local high-resolution satellite provided the satellite imagery collected between October and April, a time period in which many aquaculture facilities were operating. The ANN classification method was used for automatic detecting such as cage, longline and buoy type. Furthermore, shape files were generated using a digitizing image processing method that incorporates polygon generation techniques. In this study, our newly developed prototype method detected aquaculture facilities at a rate of 93%. The suggested method overcomes the limits of existing monitoring method using aerial photographs, but also assists experts in detecting aquaculture facilities. Aquaculture facility detection systems must be developed in the future through application of image processing techniques and classification of aquaculture facilities. Such systems will assist in related decision-making through aquaculture facility monitoring.

• The Journal of the Acoustical Society of Korea
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• v.19 no.7
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• pp.34-41
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• 2000

This paper proposes a new double-talk detection algorithm which is based on the fuzzy rules, in the adaptive echo canceller of telecommunication system. In this method, the two inputs of the fuzzy inference for detecting double-talk condition are used. One is the cross-correlation coefficient between the error signal and the primary signal which is the summation of the real echo signal and the near-end signal. The other one is the cross-correlation coefficient between the estimation error signal and the primary signal. The fuzzy controller makes a fuzzification for two inputs by the membership functions of trapezoid does the max-min composition using if-then rules. The composed result is defuzzificated by the center gravity method. And by defuzzificated values, the double-talt the echo path variance, and the echo path variance during the double-talk are detected. It is confirmed by computer simulation that this fuzzy double-talk detector is able to estimate the double talk and the echo path variation condition, and even track echo path variation more accurately than the conventional algorithm during the double-talk period.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12B
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• pp.1058-1067
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• 2006

In this paper, we propose a inband/outband broadcast method for hidden incumbent system detection of medium access control layer for wireless regional area network systems using cognitive radio technology. Through some extra channels that are not currently used, a short message is broadcasted. The message allows CPE detecting an appearance of incumbent system to send sensing report to CR BS. For the hidden incumbent system report message, the BS needs a process or method for allocation of upstream resource to CPEs. And transmitting multiple out-band signals has a possibility to collide with out-band signals of other co-located WRAN BSs. To avoid out-band signal collision, BSs randomly select it out-band signal broadcasting time within the pre-defined explicit out-band signaling, period. And fractional Bandwidth Usage allows WRAN BSs to efficiently use bandwidth.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.71-85
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• 1993

The Cycloconverter that the author is going to treat in this paper, has strong advantages over the D.C. Link Inverter in points of chattering torque problem and natural commutation. Thus, the Cycloconverter is expected to be well applied to large and low-speed machines which require better speed control at low frequency. But the control circuit of Cycloconverter has two weak points described as follows. 1) Because of its rather complicated control circuit, it is likely to be illoperating due to unexpected noise signals, thus the higher the accuracy and reliability of the circuit is required to be, the more the circuit may cost. 2) Because the load current is not purely sinusoidal, the Cycloconverter may possibly be destroyed in case of inaccurate convert switching resulted from the difficulties in detecting the load current-zero and the current direction at the moment. In this paper, the author first of all intends to design and build a modified VVVF-type Noncirculating Current Cycloconverter to which recently proposed control methods are applied for improving the circuit simplicity, the control performance, and the system reliability. And then, experiments for observing the output waveforms of the Cycloconverter which is controlled by Singled-Board Computer using 8086 16-bit microprocesser are carried out. Finally the author concludes the result of this study as follows. 1) By replacing the conventional analog control circuits such as Reference Wave Generator, Cosine Timing Wave Generator, and Comparator with softwares, a great circuit simplicity is achieved. 2) The output of the designed Cycloconverter changes its frequency very fast without showing discontinuity of its waveform, and this waveform characteristics enables the smooth speed control of Induction Motor. 3) The design control circuit of Cycloconverter can be applied to the systems of 12 or 24 pulses because of its short processing period.

• Journal of Conservation Science
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• v.29 no.4
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• pp.367-378
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• 2013

Microstructures and nonmetallic inclusions of five forged iron axes and one cast iron axe were analyzed. The axes were excavated from the Proto-Three Kingdom Period site located in Yangchon, Gimpo. The forging objects were made of almost pure iron and low carbon steel, and only one among five were quenched after its figuration. Malleable cast iron structures showing on the casting suggest that the decarbonized casting method were applied. According to the results of nonmetallic inclusion analysis, the axes were produced by hammering the iron bloom which was attained with low-temperature -solid-reduction-method. Showing higher Fe content over $SiO_2$, it is assumed that the re-collecting rate of Fe was low because of the insufficient forging temperature and the impurities were included during the smelting process. It is assumed that the lime was used as a preparation because of detecting high Ca contents.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.6
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• pp.1-8
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• 2009

Detecting entry and exit zones in a view covered by multiple cameras is an essential step to determine the topology of the camera setup, which is critical for achieving and sustaining the accuracy and efficiency of multi-camera surveillance system. In this paper, a graph theoretic clustering method is proposed to detect zones using data points which correspond to entry and exit events of objects in the camera view. The minimum spanning tree (MST) is constructed by associating the data points. Then a set of well-formed clusters is sought by removing inconsistent edges of the MST, based on the concepts of the cluster balance and the cluster density defined in the paper. Experimental results suggest that the proposed method is effective, even for sparsely elongated clusters which could be problematic for expectation-maximization (EM). In addition, comparing to the EM-based approaches, the number of data required to obtain stable outcome is relatively small, hence shorter learning period.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.827-832
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• 2012

In this paper, we will design the speed measurement board of LEO Satellite's reaction wheel which has two speed measuring methods as M-Method type and T-Method type. therefore we can use the advantage of two methods. and we will verify the availability of design on the on-board computer at the real LEO Satellite(KOMPSAT-3). In the reaction wheels satellite that can change the satellite's attitude is one of the leading drivers by the rotational inertia of the motor will perform attitude control. Reaction methods for detecting wheel rotation speed generated during a certain period T internal reaction wheel tacho pulse counting M-Method to detect wheel speed and wheel tacho pulses are generated by measuring the time between the detection rate can be divided into T-Method. M-method is simple to implement and benefit measurement time is constant, but slow fall in the velocity measurement accuracy is a disadvantage. In contrast, the time between tacho pulses to measure the T-Method to measure the precise speed at low speed and to measure the time delay is small, has the advantage. However, this method also in the actual implementation and the complexity of the operation at different speeds depending on the speed of operation has the disadvantage.

• Women's Health Nursing
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• v.7 no.4
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• pp.419-431
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• 2001

The purpose of this study was to provide the correct knowledge on GDM(Gestational Diabetes Mellitus) to nurses for effective care of pregnant women with GDM by investigating the knowledge of nurses about GDM. The subjects of this study were 557 nurses who work at six general hospitals in Seoul and Gyung-Gi province of Korea. The data were collected from November, 2000 to December, 2000, using a 30-item knowledge questionnaire about GDM consisted of eight areas developed by Choi et al. (2000): characteristics and diagnosis, influence on pregnancy, goal and method of management, diet therapy, exercise therapy, insulin therapy, hypoglycemia and hyperglycemia and postpartum care of GDM. The data were analyzed by SAS program for t-test, ANOVA and Scheffe test. The results were as follows: 1. The mean score of knowledge on GDM was 23.18. 2. There were significant differences according to age(p= 0.002), education background (p= 0.045). working period(p= 0.000), working unit(p= 0000), working experience of obstetric and gynecologic (OS & GY) units(p= 0.000), experience of pregnancy (p=0.003) and experience of delivery (p=0.014) in GDM knowledge. 3. The level of each area on GDM knowledge was as follows; 1) Area of characteristics and diagnosis of GDM The mean score of this area was 0.79. Nurses' knowledges were significantly different by age(p=0.003), marital status (p=0.018), working period(p=0.002) working unit(p=0.007), working experience of OB & GY units(p=0.005), experience of pregnancy(p=0.034) and experience of delivery(p=0.033). 2) Area of influence on pregnancy The mean score of this area was 0.93. Nurses' knowledges were significantly different by age(p=0.006), working unit (p=0.000) and working experience of OB & GY units(p= 0.000). 3) Area of goal and method of management The mean score of this area was 0.70. Nurses' knowledges were significantly different by age(p=0.004), region(p=0.006), education background(p=0.013), marital status(p=0.007), working period(p=0.000), working unit(p=0.011), working experience of OB & GY units(p=0.002), experience of pregnancy(p=0.025) and experience of delivery(p=0.043). 4) Area of diet therapy. The mean score of this area was 0.74. Nurses' knowledges were significantly different by age(p=0.002), region(p=0.011), marital status (p=0.001). working period (p=0.007). working unit(p=0.002), working experience of OB & GY units(p=0.001), experience of pregnancy(p=0.001), experience of delivery(p=0.011) and diabetes patients in family members(p=0.032). 5) Area of exercise therapy. The mean score of this area was 0.83. There were not significant differences in all general characteristics. 6) Area of insulin therapy The mean score of this area was 0.61. Nurses' knowledges were significant differences by age (p=0.024), marital status (p=0.048), working period(p=0.027), working unit(p=0.002), working experience of OB & GY units(p=0.000), experience of pregnancy (p=0.047) and experience of delivery(p=0.040). 7) Area of hypoglycemia and hyperglycemia. The mean score of this area was 0.83. Nurses' knowledges were significantly different by marital status (p=0.027), working period(p=0.001). experience of pregnancy(p=0.020) and experience of delivery(p=0.010). 8) Area of postpartum care The mean score of this area was 0.69. Nurses' knowledges were significantly different by working unit(p=0.000), working experience of OB & GY units (p=0.000) and working experience of medical unit(p=0.047). The results of this study are suggested that nurses might be taught systemically and individually about GDM so that they can become more proficient in detecting and preventing GDM, and therefore they will feel confident to teach GDM to women.

• Journal of Internet Computing and Services
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• v.12 no.2
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• pp.85-101
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• 2011

The recommender system analyzes users' preference and predicts the users' preference to items in order to recommend various items such as book, movie and music for the users. The collaborative filtering method is used most widely in the recommender system. The method uses rating information of similar users when recommending items for the target users. Performance of the collaborative filtering-based recommendation is lowered when attacker maliciously manipulates the rating information on items. This kind of malicious act on a recommender system is called 'Recommendation Attack'. When the evaluation data that are in continuous change are analyzed in the perspective of data stream, it is possible to predict attack on the recommender system. In this paper, we will suggest the method to detect attack on the recommender system by using the stream trend of the item evaluation in the collaborative filtering-based recommender system. Since the information on item evaluation included in the evaluation data tends to change frequently according to passage of time, the measurement of changes in item evaluation in a fixed period of time can enable detection of attack on the recommender system. The method suggested in this paper is to compare the evaluation stream that is entered continuously with the normal stream trend in the test cycle for attack detection with a view to detecting the abnormal stream trend. The proposed method can enhance operability of the recommender system and re-usability of the evaluation data. The effectiveness of the method was verified in various experiments.