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A Study on Aerobic Composting of Food Waste with Controlling Temperature by Air Flow Rate (온도를 공기량으로 제어한 음식물 쓰레기 호기성 퇴비화에 관한 연구)

  • Hwang, Seon-Hyeon;Sin, Chang-Ho;Sin, Bu-Yeong;Jo, Mu-Hwan
    • KSBB Journal
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    • v.14 no.5
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    • pp.621-627
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    • 1999
  • A food waste composting apparatus of 450 L was designed for and tested with changing conditions of inlet air flow rate, agitation and inoculation. Agitation was done twice per day for 5 min and inlet air flow rate was set as 22.7 L/min for RUN 1. For RUN 2 and RUN 3, agitation was continuous, and inlet air flow rate was changed frequently as 10 L/min, 15 L/min and 20 L/min in order to maintain temp. above 5$0^{\circ}C$, and the concentration of $O_2$over 7 mol%. The compost of RUN3 was inoculated with 10 wt% of accomplished compost, and it was compared with RUN 1 and 2 to show the effect of inoculation. The composting rates of RUN 2 and RUN 3 were faster than that of RUN 1, because agitation was continuous and temperature was controlled in RUN 2 and RUN 3. Inoculated RUN 3 was better than RUN 1 and RUN 2 in the concentrations of $CO_2$and reduction of volatile solids. while the effect of inoculation on C/N ratios, pH change and the numbers of microoragnisms was not clearly appeared.

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A Study on the Manufacturing Processability of Automatic Winding Device for Manufacturing Strand Specimens (스트랜드 시편 제작 장치의 제작 공정성 연구)

  • Cha, Jae Ho;Jang, Jeong Keun;Lee, Bo Mi;Yoon, Sung Ho
    • Composites Research
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    • v.33 no.5
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    • pp.315-320
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    • 2020
  • In this study, when strand specimens were manufactured using an automatic winding device to obtain uniform strand specimens, analysis and test were conducted to investigate the effect of thermal expansion of the mandrel on strand specimens. Also, necessity of changing materials and mandrel configuration was checked. According to the results, strand specimen received unintended tension that was created by thermal expansion of the mandrel and this unintended tension depended on the curing temperature and position of specimens. Tensile test was conducted to check that initial tension affected on the performance of carbon fiber tow prepreg. All other conditions were fixed and only the initial tension was controlled at 40 N, 60 N, and 80 N. From the results of analysis and test, neither additional tension and tension deviation due to the thermal expansion of the mandrel and the initial tension difference had a significant effect on tensile test results, because carbon fiber had sufficiently high strength compared with tension. Therefore, it was confirmed that the change of the mandrel material and configuration of the automatic winding device was unnecessary.

Current Research Trends on Surface Modification of Pressure-driven Membranes for Fouling Mitigation (압력 구동 기반 분리막의 막 오염 저감을 위한 표면 개질 방법 최신 연구 동향)

  • Jun, Byung-Moon;Lee, Hyung Kae;Kim, Woo Jeong;Park, Jihun;Kim, Jong Hyeok;Kwon, Young-Nam
    • Membrane Journal
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    • v.28 no.1
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    • pp.1-20
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    • 2018
  • Fresh water is an important resource for humans, and pressure-driven membrane technology has been widely known as an energy-efficient method to obtain water resource. However, membrane fouling phenomenon, which is one of the major issue during operation, deteriorates membrane permeability. These fouling is usually affected by interaction between surface of membrane and various foulants, therefore, modification of membrane's surface is one of the methods to improve fouling-resistance. This review focuses on the method to modify surface of pressure-driven membranes such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Specifically, there are two different surface modification methods: (1) adsorption and coating as the physical modification methods, (2) cross-linker, free radical polymerization (FRP), atom transfer radical polymerization (ATRP), plasma/UV-induced polymerization as the chemical modification methods. This review introduces the physico - chemical surface modification methods reported in recent papers and suggests research directions for membrane separation which can increase membrane fouling resistance.

Analysis of Trial Test for ATP On-board Equipment of Tilting Train (틸팅열차 ATP 차상장치의 시운전시험 분석)

  • Baek, Jong-Hyen
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.10
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    • pp.3911-3916
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    • 2010
  • In this paper we describe contents and results on running test for ATP on-board equipment, which has propelled as one of the research projects, so called, "Reliability assessment and operation technology development for Korean-type tilting trains" in order to ensure the safety and operation efficiency of tilting trains. We developed tilting trains for the speed-up of conventional lines and for the passenger service improvement where the KTX is not available. And we made progress the operation trial test in the 120,000 km distance with the use of ATS equipment, used in existing lines, for the purpose of the reliability assessment of the developed tilting trains. We decided to accelerate the speed for more than 200km/h with respect to the 6 existing lines including Jungang-line and Chungbuk-line where KTX has not operated. According to this decision, Train control system is to be changed from ATS to ATP. We should have installed an ATP on-board unit in tilting trains and verified the operational suitability, therefore we installed the same ATP on-board unit on tilting trains as that used in the ATP construction project on Gyeongbu-line and Honam-line, and verified that the function and performance of the installed ATP on-board unit conformed to the tilting trains operation.

Construction Methods of Switching Network for a Small and a Large Capacity AMT Switching System (소용량 및 대용량의 ATM시스템에 적합한 스위칭 망의 구성 방안)

  • Yang, Chung-Ryeol;Kim, Jin-Tae
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.4
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    • pp.947-960
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    • 1996
  • The primary goal for developing high performance ATM switching systems is to minimized the probability of cell loss, cell delay and deterioration of throughput. ATM switching element that is the most suitable for this purpose is the shared buffer memory switch executed by common random access memory and control logic. Since it is difficult to manufacture VLIS(Very Large Scale Integrated circuit) as the number of input ports increased, the used of switching module method the realizes 32$\times$32, 150 Mb/s switch utilizing 8$\times$8, 600Mb/s os 16$\times$16, 150Mb/s unit switch is latest ATM switching technology for small and large scale. In this paper, buffer capacity satisfying total-memory-reduction effect by buffer sharing in a shared buffer memory switch are analytically evalu ated and simulated by computer with cell loss level at traffic conditions, and also features of switching network utilizing the switching module methods in small and large-capacity ATM switching system is analized. Based on this results, the structure in outline of 32$\times$32(4.9Gb/s throughput), 150Mb/s switches under research in many countries is proposed, and eventually, switching-network structure for ATM switching system of small and large and capacity satisfying with above primary goals is suggested.

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The Design of Messaging System for Prescription Data Interchange (처방전달을 위한 메시징시스템의 설계)

  • 김동호;류근호;손현준
    • Proceedings of the Korea Society for Industrial Systems Conference
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    • 1999.12a
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    • pp.209-218
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    • 1999
  • 처방전달시스템은 처방의 수행은 의사가, 그에 따른 의약품조제는 약사가 수행함으로써 의약품의 오․남용을 방지하기 위한 의약분업의 실시에 따른 국민불편의 최소화와 약화사고에 따른 인증문제 등을 지원하기 위한 정보시스템이다. 처방전달시스템은 환자 개인정보의 허용된 범위 내에서의 공유와 공유를 위한 각종 개인정보 보호장치, 처방의 안전한 전달을 위한 내용의 비밀보장과 위변조방지 및 송신자와 수신자의 인증을 위한 장치가 필수적으로 필요하다. 또한 자료의 생명주기 측면에서 본다면, 처방전의 생성은 병․의원에서 이루어지며 소멸은 약국 및 환자에의해 이루어진다. 자료의 유통과정에 살펴보면 처방전달시스템의 주요성공요인은 정보의 생산자인 병․의원(의사)의 적극적인 정보제공의지와 이를 지원하는 편리한 정보시스템의 구축이라고 할 수 있다. 정보의 생산자인 병․의원 정보시스템 환경은 다양하고 복잡하기 때문에 기존의 애플리케이션을 이용하면서 처방의 전송을 위해서는 기존 애플리케이션 및 플랫폼에 독립적이며 자료의 적합한 취합과 통합이 가능하도록 지원하는 시스템이 필요하다. 처방전달 메시징시스템은 이러한 복합적인 정보시스템 환경을 지원하며 동시에 처방정보의 안전한 전달을 위해 플랫폼으로 실행될 수 있는 시스템을 말한다. 또한 처방의 비교적 짧은 생명주기와 지역적 생산, 유통구조를 적합하게 지원하기 위해 지역별 독립시스템의 구축과 공통정보 활용을 위한 중앙시스템과의 역할분담 모델에 근거한 분산시스템의 구축이 요구된다. 본 연구에서의 처방전달 메시징시스템은 일반적인 메시지서비스의 특성을 기본으로 자료전달을 위해 자료 암호화와 복호화, 송신자와 수신자에 대한 인증 및 자료접근 제한기능을 제공하며 각 클라이언트와 서버간의 실시간 연결 혹은 지연연결을 지원하는 독립적인 애플리케이션이다. 이러한 처방전달 메시징시스템을 구성하는 각 요소에 대해 정의하고 개념적 모델을 설계하고자 한다.에게 청구되며, 소비자에게 전송 되는 청구서는 사용자DB를 참조하여 사용자가 미리 정의한 원하는 형태로 변환되어 전달되며, 필요시 암호화 과정을 거치는 것이 가능해야 한다. 전송된 청구서는 전자우편의 경우, 암호해독이 가능한 전용 브라우저를 통해 열람 되며, 이는 다시 전용 브라우저를 통해 지불인증이 승인되어 청구 제시서버에게 전송된다. EBPP 시스템의 제어 흐름은 크게 기업이 청구 정보를 소비자에게 제시하는 흐름과 소비자의 지불 승인으로 인해 기업이 은행에 지불을 요구하는 흐름으로 구분할 수 있다. 본 논문에서는 통합 청구서버 및 정구 제시서버의 역할 및 구성 요소들에 대해 서술하고, EBPP 시스템과 연동하여야 하는 메일 서버와의 상호 작용에 대해 서술할 것이다. 본 시스템을 아직 구현이 되지 않은 관계로 시스템의 성능 등의 수치적 결과를 제시할 수 없는 상태다., 취약계층을 위한 일차의료, 의약관리), ${\circled}2$ 보건소 조직 개편 및 민간의료기관과 협력체계 확립, ${\circled}3$ 전문인력 확보 및 인력구성 조정, 그리고 ${\circled}4$ 방문보건사업의 강화 등이다., 대사(代謝)와 관계(關係)있음을 시사(示唆)해 주고 있다.ble nutrient (TDN) was highest in booting stage (59.7%); however no significant difference was found among other stages. The concentrations of Ca and P were not different among mature stages. According to these results, the yellow ripe period is appropriate to harvest the whole crop rice for forage considering dry matter yields,

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Cracking Behavior of RC Tension Members Reinforced with Amorphous Steel Fibers (비정질 강섬유로 보강된 철근콘크리트 인장부재의 균열거동)

  • Park, Kyoung-Woo;Lee, Jun-Seok;Kim, Woo;Kim, Dae-Joong;Lee, Gi-Yeol
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.475-482
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    • 2014
  • This paper presents the experimental results concentrically reinforced concrete tension members and compares cracking behavior of amorphous steel fiber and normal steel fiber reinforced concrete members. Two kind of steel fibers were included as a major experimental parameter together with the six cover thickness to bar diameter ratio ($c/d_b$). The presence of amorphous steel fibers effectively controlled the splitting cracks initation and propagation. In the amorphous steel fiber reinforced specimens, no splitting cracks were observed that becomes higher with cover thickness to bar diameter ratio is 2.0. Crack spacing of the each specimens reinforced with amorphous steel fibers and normal steel fibers becomes larger with the increase in cover thickness, and also measured maximum and average crack spacing are significantly smaller than current design code provision. Based on the measured crack spacings, a relationships for predicting the crack spacing is proposed using the measured average crack spacing in amorphous steel fiber reinforced concrete tension members.

Developement of Planar Active Array Antenna System for Radar (평면형 능동 위상 배열 레이더용 안테나 시스템 개발)

  • Chon, Sang-Mi;Na, Hyung-Gi;Kim, Soo-Bum;Lee, Jeong-Won;Kim, Dong-Yoon;Kim, Seon-Joo;Ahn, Chang-Soo;Lee, Chang-Hee
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.12
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    • pp.1340-1350
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    • 2009
  • The design and implementation of planar Active Phased Array Antenna System are described in this paper. This Antenna system operates at X-band with its bandwidth 10 % and dual polarization is realized using dual slot feeding microstrip patch antenna and SPDT(Single Pole Double Through) switch. Array Structure is $16\times16$ triangular lattice structure and each array is composed of TR(Transmit & Receive) module with more than 40 dBm power. Each TR module includes digital attenuator and phase shifter so that antenna beam can be electronically steered over a scan angle$({\pm}60^{\circ})$. Measurement of antenna pattern is conducted using a near field chamber and the results coincide with the expected beam pattern. From these results, it can be convinced that this antenna can be used with control of beam steering and beam shaping.

Cybertrap : Unknown Attack Detection System based on Virtual Honeynet (Cybertrap : 가상 허니넷 기반 신종공격 탐지시스템)

  • Kang, Dae-Kwon;Hyun, Mu-Yong;Kim, Chun-Suk
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.6
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    • pp.863-871
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    • 2013
  • Recently application of open protocols and external network linkage to the national critical infrastructure has been growing with the development of information and communication technologies. This trend could mean that the national critical infrastructure is exposed to cyber attacks and can be seriously jeopardized when it gets remotely operated or controlled by viruses, crackers, or cyber terrorists. In this paper virtual Honeynet model which can reduce installation and operation resource problems of Honeynet system is proposed. It maintains the merits of Honeynet system and adapts the virtualization technology. Also, virtual Honeynet model that can minimize operating cost is proposed with data analysis and collecting technique based on the verification of attack intention and focus-oriented analysis technique. With the proposed model, new type of attack detection system based on virtual Honeynet, that is Cybertrap, is designed and implemented with the host and data collecting technique based on the verification of attack intention and the network attack pattern visualization technique. To test proposed system we establish test-bed and evaluate the functionality and performance through series of experiments.

Identification of Motor Parameters and Improvement of Voltage Error for Improvement of Back-emf Estimation in Sensorless Control of Low Speed Operation (저속 센서리스 제어의 역기전력 추정 성능 향상을 위한 모터 파라미터 추정과 전압 오차의 개선)

  • Kim, Kyung-Hoon;Yun, Chul;Cho, Nae-Soo;Jang, Min-Ho;Kwon, Woo-Hyen
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.5
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    • pp.635-643
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    • 2018
  • This paper propose a method to identify the motor parameters and improve input voltage error which affect the low speed position error of the back-emf(back electromotive force) based sensorless algorithm and to secure the operation reliability and stability even in the case where the load fluctuation is severe and the start and low speed operation frequently occurs. In the model-based observer used in this paper, stator resistance, inductance, and input voltage are particularly influential factors on low speed performance. Stator resistance can cause resistance value fluctuation which may occur in mass production process, and fluctuation of resistance value due to heat generated during operation. The inductance is influenced by the fluctuation due to the manufacturing dispersion and at a low speed where the change of the current is severe. In order to find stator resistance and inductance which have different initial values and fluctuate during operation and have a large influence on sensorless performance at low speed, they are commonly measured through 2-point calculation method by 2-step align current injection. The effect of voltage error is minimized by offsetting the voltage error. In addition, when the command voltage is used, it is difficult to estimate the back-emf due to the relatively large distortion voltage due to the dead time and the voltage drop of the power device. In this paper, we propose a simple circuit and method to detect the voltage by measuring the PWM(Pulse Width Modulation) pulse width and compensate the voltage drop of the power device with the table, thereby minimizing the position error due to the exact estimation of the back-emf at low speed. The suitability of the proposed algorithm is verified through experiment.