• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.152-158
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• 2004

A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The designed frequency synthesizer consists of a 1.75 GHz master oscillator - which also operates as a harmonic generator - and a 10.5 GHz slave oscillator. A 1.75 GHz master oscillator based on PLL technique used two transistors - one constitutes the active part of VCO and the other operates as a buffer amplifier as well as harmonic generator. The first stage operates a fixed locked oscillator and using the BJT transistor whose cutoff frequency is 45 GHz, the second stage is designed, operating as a harmonic generator. The 6th harmonic which is produced from the harmonic generator is injected into the following slave oscillator which also behaves as an amplifier having about 45 dB gain. The realized frequency synthesizer has a 7.4 V/49 mA, -0.5 V/4 mA of the low DC power consumption, 4.53 dBm of output power, and a phase noise of -95.09 dBc/Hz and -108.90 dBc/Hz at the 10 kHz and 100 kHz offset frequency, respectively.

• Convergence Security Journal
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• v.20 no.4
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• pp.187-196
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• 2020

In order to manage information security risk, various information security level evaluation and information security management system certification have been conducted on a larger scale than ever. However, there are continuous cases of infringement of information protection for companies with excellent information security evaluation and companies with excellent information security management system certification. The existing information security risk management methodology identifies and analyzes risks by identifying information assets inside the information system. Existing information security risk management methodology lacks a review of where cyber threats come from and whether security devices are properly operated for each route. In order to improve the current risk management plan, it is necessary to look at where cyber threats come from and improve the containment level for each inflow section to absolutely reduce unnecessary cyber threats. In addition, it is essential to measure and improve the appropriate configuration and operational level of security equipment that is currently overlooked in the risk management methodology. It is necessary to block and enter cyber threats as much as possible, and to detect and respond to cyber threats that inevitably pass through open niches and use security devices. Therefore, this paper proposes additional evaluation items for evaluating the containment level against cyber threats in the ISMS-P authentication items and vulnerability analysis and evaluation items for major information and communication infrastructures, and evaluates the level of security equipment configuration for each inflow.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.409-414
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• 2021

Tightness performance that blocks compartments is important for surface ships to achieve superior mission performance and survivability in combat environments. To meet the above requirements, airtightness of the structural elements and the appropriate strength to specific areas are checked during a test run after ship construction. In particular, air tests of compartments adjacent to the water surface are performed. In an air test, air is injected into the compartment up to the test pressure of the test memo. The pressure drop value is checked after 10 minutes to determine if the requirements of the corresponding area are satisfied. In summer, however, when the influence of the outside temperature is large, a phenomenon in which the internal pressure increases during the air test was identified. This phenomenon reduces the reliability of the test result. Therefore, a system was designed to compensate for temperature changes in the compartments through this study. The developed system calculates the amount of pressure change caused by a temperature change in the compartment and outputs a correction value. The pressure change was calculated using the ideal gas equation, reflecting the maintenance, increase, and decrease in temperature during the test process. A comparison of the calculated pressure correction value with the database of NIST REFPROP revealed a difference of 0.126% to a maximum of 0.253%.

• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.157-173
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• 2011

As the Internet use explodes recently, the malicious attacks and hacking for a system connected to network occur frequently. This means the fatal damage can be caused by these intrusions in the government agency, public office, and company operating various systems. For such reasons, there are growing interests and demand about the intrusion detection systems (IDS)-the security systems for detecting, identifying and responding to unauthorized or abnormal activities appropriately. The intrusion detection models that have been applied in conventional IDS are generally designed by modeling the experts' implicit knowledge on the network intrusions or the hackers' abnormal behaviors. These kinds of intrusion detection models perform well under the normal situations. However, they show poor performance when they meet a new or unknown pattern of the network attacks. For this reason, several recent studies try to adopt various artificial intelligence techniques, which can proactively respond to the unknown threats. Especially, artificial neural networks (ANNs) have popularly been applied in the prior studies because of its superior prediction accuracy. However, ANNs have some intrinsic limitations such as the risk of overfitting, the requirement of the large sample size, and the lack of understanding the prediction process (i.e. black box theory). As a result, the most recent studies on IDS have started to adopt support vector machine (SVM), the classification technique that is more stable and powerful compared to ANNs. SVM is known as a relatively high predictive power and generalization capability. Under this background, this study proposes a novel intelligent intrusion detection model that uses SVM as the classification model in order to improve the predictive ability of IDS. Also, our model is designed to consider the asymmetric error cost by optimizing the classification threshold. Generally, there are two common forms of errors in intrusion detection. The first error type is the False-Positive Error (FPE). In the case of FPE, the wrong judgment on it may result in the unnecessary fixation. The second error type is the False-Negative Error (FNE) that mainly misjudges the malware of the program as normal. Compared to FPE, FNE is more fatal. Thus, when considering total cost of misclassification in IDS, it is more reasonable to assign heavier weights on FNE rather than FPE. Therefore, we designed our proposed intrusion detection model to optimize the classification threshold in order to minimize the total misclassification cost. In this case, conventional SVM cannot be applied because it is designed to generate discrete output (i.e. a class). To resolve this problem, we used the revised SVM technique proposed by Platt(2000), which is able to generate the probability estimate. To validate the practical applicability of our model, we applied it to the real-world dataset for network intrusion detection. The experimental dataset was collected from the IDS sensor of an official institution in Korea from January to June 2010. We collected 15,000 log data in total, and selected 1,000 samples from them by using random sampling method. In addition, the SVM model was compared with the logistic regression (LOGIT), decision trees (DT), and ANN to confirm the superiority of the proposed model. LOGIT and DT was experimented using PASW Statistics v18.0, and ANN was experimented using Neuroshell 4.0. For SVM, LIBSVM v2.90-a freeware for training SVM classifier-was used. Empirical results showed that our proposed model based on SVM outperformed all the other comparative models in detecting network intrusions from the accuracy perspective. They also showed that our model reduced the total misclassification cost compared to the ANN-based intrusion detection model. As a result, it is expected that the intrusion detection model proposed in this paper would not only enhance the performance of IDS, but also lead to better management of FNE.

• Journal of the korean veterinary medical association
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• v.44 no.9
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• pp.803-818
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• 2008

동물의 결핵은 Mycobacterium bovis의 감염에 의한 만성 소모성 질병이며 인수공통전염병이다. 동물로부터 사람으로의 결핵 전염은 생유 섭취하던 시대에 상당히 많이 보고되었다. 우유의 살균처리와 소에서 피내진단에 의한 양성우 살처분 및 보상금 지급 정책을 전개하면서 M. bovis의 사람전염은 급격히 감소하였다. 소 결핵은 우리나라에서 연간 0.15% 내외의 발생을 보이고 있으며, 발생의 주원인으로는 외부입식소, 인근발생농장, 과거발생농장의 사후관리소홀 등이다. 사람 결핵의 주원인균인 M. tuberculosis와 M. bovis는 유전체가 99.9% 유사하며, M. bovis를 M. tuberculosis의 아종으로 분류하기도 한다. 두 세균은 M. tuberculosis complex에 속하며, M. tuberculosis와 M. bovis이외에도 M. africanum, M. canettii, M. microti, M. pinnipedii 등이 있다. M. bovis는 M. tuberculosis complex중에서 가장 넓은 숙주범위를 가진다. M. bovis의 대표적인 숙주는 종이름에도 나타나 있듯이 소이다. 소결핵 전파원으로서는 M. bovis에 감염된 소가 가장 중요하다. 소 이외에도 면양, 산양, 말, 돼지, 사슴, 엘크, 영양 (antelope, kudus, elands, sitatungas, oryxes, addaxes), 개, 고양이, 흰족제비 (ferrets), 낙타, 여우, 밍크, 오소리, 쥐, 영장류, 라마, 맥 (tapirs), 코끼리, 코뿔소 (rhinoceroses), 주머니쥐, 땅다람쥐 (ground squirrels), 수달 (otters), 물개, 산토끼 (hares), 두더쥐 (moles), 너구리 (raccoons), 코요테, 사자, 호랑이, 표범, 살쾡이 (lynx) 등에 감염될 수 있으나, 대부분 종결숙주 (spillover host)로 가축의 결핵방제가 유지되고 있는 국가에서는 야생동물 결핵의 가축 전염이 문제시되고 있다. M. bovis는 주로 호흡기와 소화기를 통하여 감염되며, 결핵결절이 형성되는 부위를 관찰하면 감염경로를 추정할 수 있다. 결핵에 감염되면, 초기에는 뚜렷한 임상증상을 보이지 않으나, 아침, 추운 날씨, 또는 운동 중에 심한 기침을 하며, 호흡곤란을 일으킬 수 있다. 결핵은 감염되어도 대부분 무증상이기 때문에 피내진단, 결핵결절 병리소견, 원인균 분리 등에 의해 진단하여야 한다. 감염된 결핵균은 탐식세포에 탐식되어 특징적인 육아종성 결절 병변으로 진행된다. 현재 결핵은 피내진단과 결핵결절 병리소견 등에 의해 판정하고 있다. 최신 진단법으로는 피내진단을 대체할 수 있는 인터페론 감마 검사법과 우군의 결핵 스크리닝과 말기 결핵 검사에 우수한 항체진단법이 개발되어 있다. 그러나, 소 결핵 근절을 위해서는 일관성있는 진단법과 진단기준을 적용하는 것이 중요한 성공요인중 하나이다. 소결핵 청정국인 호주와 캐나다에서는 피내진단과 도축장 결절검사를 결핵 양성우 색출방법의 근간으로 삼고 있으며, 소결핵 근절의 최종단계에 이르러서는 특이적인 검사법을 적용하였지만, 근절목적상 민감성이 높은 피내진단법을 사용하였다. 이와 더불어, 피내진단 양성우의 부검소견과 원인균 분리를 통해 결핵을 확진하여 출처농장의 역추적 검사를 통하여 결핵 양성소를 제거하였다. 한편, 결핵의 농장간 및 지역간 전파방지를 위해 결핵 청정농장과 결핵 오염농장, 결핵 청정지역과 결핵 오염지역 구분을 통하여 결핵 오염농장과 결핵 오염지역으로부터 결핵 청정농장과 결핵 청정지역으로의 이동전 결핵 검진을 통해 개체 이동에 따른 결핵 전파를 근본적으로 차단하는 시스템을 엄격히 적용한 것이 주요한 성공 요인중 하나였다. 호주 결핵 근절정책 성공요인을 요약하면, 일관성 있는 결핵진단법 적용, 양성우 출처농장의 철저한 역추적 검사, 개체 이동전 결핵 음성증명 확인, 농가단체의 경제적 및 방역상 적극적인 지원 및 협조 결핵의 지속적인 모니터 링과 현장요구에 부응하는 방제신기술의 지속적인 연구개발 등을 들 수 있다. 최근 들어 국내 동물 결핵은 소, 특히, 한우의 결핵발생이 증가하고 있으며, 사슴 결핵발생도 증가하고 있다. 농장간 및 지역간에 결핵 감수성 가축, 특히, 소와 사슴의 거래가 아주 복잡하게 이루어지고 있는 현실을 고려할 때, 결핵전파의 주원인인 결핵감염 소나 사슴의 농장내 반입을 철저히 차단해야 할 것이다. 이때, 개체 검사는 물론이고, 출처농장에 대한 결핵 음성을 확인한 후 입식하여야 할 것이며, 입식 후에도 60일정도 격리사육하면서 피내진단등 결핵검진 후 음성인 경우에만 합사하여야 할 것이다. M. bovis는 사람을 비롯한 거의 모든 온혈동물에서 결핵을 일으킬 수 있기 때문에, 결핵 감염소로 판정된 농장 종사자는 각 시도 보건소의 협조를 받아 결핵검진을 받도록 해야 한다. 농장 가축에 접촉할 수 있는 야생동물의 접촉을 차단하여야 하며, 특히, 농장 사료의 야생동물에 의한 오염을 방지할 수 있는 사료창고관리를 철저히 해야 한다. 결핵 감염소를 다룰 때는 분비물 또는 가검물에 의해 감염될 수 있기 때문에 개인방역장비 - 방역복, 마스크, 비닐장갑, 비닐장화 - 를 착용한 상태에서 다루어야 한다. 특히, 결핵 감염소를 매몰 또는 소각하는 과정에서 결핵 감염소의 배설물 및 분비물 처리를 철저히 하여야 한다. 모든 작업을 마친 후에는 개인방역장비, 매몰 또는 소각에 사용하였던 장비 등을 청소 및 소독하고 필요시 소각 또는 매몰하여야 하며, 개인감염위험과 타인 감염위험을 방지하기 위해 노출부위를 세척하여야 한다.

• Journal of Korea Water Resources Association
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• v.52 no.1
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• pp.51-60
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• 2019

The major purpose of this study is to construct an in-situ soil moisture verification network employing Frequency Domain Reflectometry (FDR) sensors for Cosmic-ray soil moisture observation system operation as well as long-term field-scale soil moisture monitoring. The test bed of Cosmic-ray and FDR verification network system was established at the Sulma Catchment, in connection with the existing instrumentations for integrated data provision of various hydrologic variables. This test bed includes one Cosmic-ray Neutron Probe (CRNP) and ten FDR stations with four different measurement depths (10 cm, 20 cm, 30 cm, and 40 cm) at each station, and has been operating since July 2018. Furthermore, to assess the reliability of the in-situ verification network, the volumetric water content data measured by FDR sensors were compared to those calculated through the core sampling method. The evaluation results of FDR sensors- measured soil moisture against sampling method during the study period indicated a reasonable agreement, with average values of $bias=-0.03m^3/m^3$ and RMSE $0.03m^3/m^3$, revealing that this FDR network is adequate to provide long-term reliable field-scale soil moisture monitoring at Sulmacheon basin. In addition, soil moisture time series observed at all FDR stations during the study period generally respond well to the rainfall events; and at some locations, the characteristics of rainfall water intercepted by canopy were also identified. The Temporal Stability Analysis (TSA) was performed for all FDR stations located within the CRNP footprint at each measurement depth to determine the representative locations for field-average soil moisture at different soil profiles of the verification network. The TSA results showed that superior performances were obtained at FDR 5 for 10 cm depth, FDR 8 for 20 cm depth, FDR2 for 30 cm depth, and FDR1 for 40 cm depth, respectively; demonstrating that those aforementioned stations can be regarded as temporal stable locations to represent field mean soil moisture measurements at their corresponding measurement depths. Although the limit on study duration has been presented, the analysis results of this study can provide useful knowledge on soil moisture variability and stability at the test bed, as well as supporting the utilization of the Cosmic-ray observation system for long-term field-scale soil moisture monitoring.

• Journal of agriculture & life science
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• v.50 no.3
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• pp.119-127
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• 2016

The current disinfection method of vehicles being applied in South Korea has various shortcomings. So, the epidemic has generated continuously at livestock farms. It is very important to develop an effective disinfection system for reduction of the epidemic. And various basic data is required for this development. Therefore, this study was performed to identify the nozzle type and proper discharge pressure of sprayers. The experiment was conducted from January 10, 2012 until February 28, 2012. All the performance measurement experiments were repeated five times. The subjects of experiment were the A, B and C company's products. The sprayed capacity, angle of spray and the covering area ratio were measured for each product. As a result, the sprayed capacity, angle of spray and the covering area ratio were increased as the discharge pressure of the sprayer was increased. In conclusion, the conical shaped of the nozzle is considered more appropriate than V-shaped, and the proper discharge pressure is expected to be at least 20kg/㎠.

• Journal of the Korean Electrochemical Society
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• v.12 no.4
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• pp.329-334
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• 2009

This study is to develop a fuel cell system applicable to an in situ NMR (Nuclear magnetic resonance) diagnosis. The in situ NMR can be used in real time monitoring of various reactions occurring in the fuel cell, such as oxidation of fuel, reduction of oxygen, transport phenomena, and component degradation. The fuel cell for this purpose is, however, to be operated in a specifically designed tubular shape toroid cavity detector (TCD), which constrains the fuel cell to have a tubular shape. This may cause difficulties in effective mass transport of reactants/products and uniform distribution of assembly pressure. Therefore, a new flow field designed in a particular way is necessary to enhance the mass transport in the tubular fuel cell. In this study, a tubular-shaped close-type flow field made of non-magnetic material is developed. With this flow field, oxygen is effectively delivered to the cathode surface and the produced water is readily removed from the membrane-electrode assembly to prevent flooding. The resulting DMFC (direct methanol fuel cell) outperforms the open-type flow field and exhibits $36\;mW/cm^2$ even at room temperature.

• Korean Journal of Organic Agriculture
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• v.15 no.3
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• pp.319-330
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• 2007

This study analyzed physical and chemical characteristics of peat soil to use peat soil as the materials fur pot media and investigated seedling quality of horticultural plants in order to use peat soil as the raw materials fur pot media. The summary of the results is as follows; The chemical characteristics of peat soil, which is main ingredient of pot media are as follows; pH was 4.9, EC was less than $2.0ds{\cdot}m^{-1}$, which interferes the growth of the plant and organic ingredient was 33%. When looking into the germination characteristics of plants according to the mixture of pot media, red pepper showed 54.2% speed of germination and 97% germination rate in peat soil single treatment. Therefore the peatsoil was appropriate for the pot media for red pepper. In case of cucumbers, in the 50 : 50 treatment of main ingredient (peat soil) and auxiliary ingredients (vermiculite, peat moss and perlite) they showed 100% speed of germination and 100% germination rate. Therefore 50 : 50 treatment was appropriate fur the pot media for cucumbers. In case of chinese cabbage, peat soil, perlite and peat moss mixture (50 : 25 : 25) treatment showed the highest speed of germination (77.5%), while the germination rate was a little lower (92.15%) than comparative soil. However, it was appropriate for the pot media for chinese cabbage. In case of watermelon, germination was bad because of the influence of EC when the teat soil ingredient is over 80%. However, in the mixture of peat soil and vermiculite (50:50) treatment, they showed 91.6% speed of germination and 100% germination rate. Therefore it was appropriate for the pot media for watermelon. When looking into the growth of the plants according to the mixture of ingredients, peat soil and perlite (50:50) mixture showed excellent seedling quality for cucumbers, peat soil and perlite (50:50) mixture showed excellent seedling quality and it was proven to be appropriate for the pot media for cucumbers. In case of watermelon, peat soil, peat moss and perlite (80 : 10 : 10) mixture showed excellent seedling quality and it was proven to be appropriate for the pot media for watermelon.

• Korean Journal of Poultry Science
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• v.33 no.1
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• pp.57-63
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• 2006

This study was conducted to investigate the effect of ventilating system of environmental controlled broiler house on broiler production. Three hundred eighty four broiler chicks (Hubbard, mean live weight of $44.5{\pm}2.0g/bird$) were reared for 2 wk. The results of the present study were summarized as follows : 1. Ammonia gas production was lower in the second and the third floors of cages compared with first floor of cages 13.5 and 13.5 vs 14.6 ppm, respectively). The observations of ammonia production in the morning and afternoon were similar. The production of carbon dioxide was not different between morning and afternoon, but it was tended to decrease in the forth floor of cages due to a fresh air 2. A wind velocity in the enclosed house was similar across lower, middle and upper section (0.57m/sec, 0.22m/sec and 0.04msec, respectively). In order to maintain an optimal air flow velocity in the cages, the duct entrance was punched, and then the air flow was full-round in the overall space in the cage. 3. Daily liveweight gain, feed intakes, and feed efficiency were not significant differences among treatments during whole experimental period (P>0.05). Therefore, the present results showed that temperature, moisture and atmosphere controlling were desirable, and air flew evenly in the cage.