• 한국수산과학회지
• /
• 제51권1호
• /
• pp.8-14
• /
• 2018

We investigated the levels of microbial contaminants and microbial hazards during dried-laver processing. We analyzed 321 samples obtained from 18 dried-laver Pyropia spp. manufacturing facilities, including water, swab-, and processing samples as well as final products. The levels of microbial contaminants, including viable cell counts (VCC) and coliform bacteria, increased as processing progressed. The sanitary indicator bacterium, Escherichia coli, was not detected in the final products although VCC levels were high, generally exceeding 5 log CFU/g. We also investigated changes in microbial contaminants at each processing step. Both VCC and total coliform dramatically increased after 4 days of continuous processing, indicating that microbial contaminants originated, mainly, from cross contamination during processing.

• 한국전기전자재료학회논문지
• /
• 제30권9호
• /
• pp.535-540
• /
• 2017

The changes in the electrical characteristics of CMOS ICs due to coupling with a narrow-band electromagnetic wave were analyzed in this study. A magnetron (3 kW, 2.45 GHz) was used as the narrow-band electromagnetic source. The DUT was a CMOS logic IC and the gate output was in the ON state. The malfunction of the ICs was confirmed by monitoring the variation of the gate output voltage. It was observed that malfunction (self-reset) and destruction of the ICs occurred as the electric field increased. To confirm the variation of electrical characteristics of the ICs due to the narrow-band electromagnetic wave, the pin-to-pin resistances (Vcc-GND, Vcc-Input1, Input1-GND) and input capacitance of the ICs were measured. The pin-to-pin resistances and input capacitance of the ICs before exposure to the narrow-band electromagnetic waves were $8.57M{\Omega}$ (Vcc-GND), $14.14M{\Omega}$ (Vcc-Input1), $18.24M{\Omega}$ (Input1-GND), and 5 pF (input capacitance). The ICs exposed to narrow-band electromagnetic waves showed mostly similar values, but some error values were observed, such as $2.5{\Omega}$, $50M{\Omega}$, or 71 pF. This is attributed to the breakdown of the pn junction when latch-up in CMOS occurred. In order to confirm surface damage of the ICs, the epoxy molding compound was removed and then studied with an optical microscope. In general, there was severe deterioration in the PCB trace. It is considered that the current density of the trace increased due to the electromagnetic wave, resulting in the deterioration of the trace. The results of this study can be applied as basic data for the analysis of the effect of narrow-band high-power electromagnetic waves on ICs.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
• /
• pp.69-72
• /
• 2000

This paper describes an SRAM write driver circuit which dissipates small power. The write driver utilizes a dual sized transistor structure to reduce operating current in the write cycle. In the case of higher voltage comparing to Vcc, only one transistor is active, while in the case of low Vcc two transistors are active so as to deliver the current twice. Thus though with the high voltage operation, the power consumption is reduced with keeping the speed in a given specification. Simulation results have verified the functionality of the new circuit and write power is reduced by 7 % per bit.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제49권9호
• /
• pp.546-551
• /
• 2000

A micromechanical switch that can be used as a logic gate is described in this paper. This switch consists of fixed input electrodes an output electrode Vcc/GND electrodes and movable plates suspended by crab-leg flexures. for mechanical switching of an electrical signal a parallel plate actuator which comes in contact with output electrode was used. Provided that movable plates are connected to Vcc and a low input voltage(ground signal) is applied to the fixed input electrodes the movable plates are pulled by an electrostatic force between the fixed input electrodes and the movable plates. the proposed micromechanical switch was fabricated by surface micromachining technology with$2\mum$ -thick poly-Si and the measured threshold voltage for ON/OFF switching was 23.5V.

• 한국재료학회지
• /
• 제17권11호
• /
• pp.574-579
• /
• 2007

Amorphous $BaTi_4O_9$ ($BT_4$) film was deposited on Pt/Si substrate by RF magnetron sputter and their dielectric properties and electrical properties are investigated. A cross sectional SEM image and AFM image of the surface of the amorphous $BT_4$ film deposited at room temperature showed the film was grown well on the substrate. The amorphous $BT_4$ film had a large dielectric constant of 32, which is similar to that of the crystalline $BT_4$ film. The leakage current density of the $BT_4$ film was low and a Poole-Frenkel emission was suggested as the leakage current mechanism. A positive quadratic voltage coefficient of capacitance (VCC) was obtained for the $BT_4$ film with a thickness of <70 nm and it could be due to the free carrier relaxation. However, a negative quadratic VCC was obtained for the films with a thickness ${\geq}96nm$, possibly due to the dipolar relaxation. The 55 nm-thick $BT_4$ film had a high capacitance density of $5.1fF/{\mu}m^2$ with a low leakage current density of $11.6nA/cm^2$ at 2 V. Its quadratic and linear VCCs were $244ppm/V^2$ and -52 ppm/V, respectively, with a low temperature coefficient of capacitance of $961ppm/^{\circ}C$ at 100 kHz. These results confirmed the potential suitability of the amorphous $BT_4$ film for use as a high performance metal-insulator-metal (MIM) capacitor.

• 전기전자학회논문지
• /
• 제13권4호
• /
• pp.57-62
• /
• 2009

본 논문에서는 10GBASE-R 형식의 PCS (Physical Coding Sublayer) 구현을 위한 회로로써 표준 속도인 156.25MHz에서 동작하면서 2단 파이프라인 구조로 64b/66b 인코더/디코더를 설계하여 가능한 클록 지연을 최소화한 회로를 제시한다. 제안하는 PCS 회로는 Verilog 하드웨어 설계 언어를 기반으로 설계하여 FPGA를 통한 기능 검증을 위해 Xilinx사의 VertexII-1000fg456 칩에서 측정하였다. 측정한 게이트 수는 47,303이고, Vcc 3.3V에서 351mW의 전력 소모를 보였다.

• 한국농공학회지
• /
• 제42권5호
• /
• pp.133-143
• /
• 2000

A large scale field test of prefabricated vertical drains was performed to anayze the effect of parameters of the very soft clay at a test site. compression index and the coefficient of horizontal consolidation obtained by back-analysis of settlement data were compared with those obtained by means of laboratory tests. Hyperbolic method, Asaoka meoth and curve fitting method were used to compute final settlement of coefficient of consolidation. The relationships of settlement measurement(Sm) versus design settlement(St) and the measurement consolidation ratio(Um) versus design consolidation (Ut) were shown as Sm=(1.0~1.1) St , Um=(1.13~1.17) Ut at 1.0m spacing of drain and Sm=(0.7~0.8)St, Um= (0.92~0.99) Ut at 1.5 m spacing of drain, respectively . The relationships of the field compression index(CcField) and virgin compression index(vcc lab) were shown as Ccfield =(1.0~1.2)vcc lab . But it was nearly within the same range when considering the error factor with the determination method of virgin compression index and the prediction back-analysis of the settlement data was larger than the coefficient of vertical consolidation, and the ratio of consolidation coefficient (Ch/Cv) was Ch =(2.4~2.9) Cv , Ch=(3.4~4.2) Cv at 1.0m and 1.5m spacing of drain, respectively.

• 한국수소및신에너지학회논문집
• /
• 제23권5호
• /
• pp.521-529
• /
• 2012

Since the energy demand for refrigeration and air-conditioning has greatly increased all over the world, thermally activated refrigeration cycle has attracted much attention. This study carries out a performance analysis of a vapor compression cycle (VCC) driven by organic Rankine cycle (ORC) utilizing low-temperature heat source in the form of sensible heat. The ORC is assumed to produce minimum net work which is required to drive the VCC without generating an excess electricity. Effects of important system parameters such as turbine inlet pressure, condensing temperature, and evaporating temperature on the system variables such as mass flow ratio, net work production, and coefficient of performance (COP) are thoroughly investigated. The effect of choice of working fluid on COP is also considered. Results show that net work production and COP increase with increasing turbine inlet pressure or decreasing condensing temperature. Out of the five kinds of organic fluids considered $C_4H_{10}$ gives a relatively high COP in the range of low turbine inlet pressure.

• 대한기계학회논문집B
• /
• 제37권12호
• /
• pp.1137-1145
• /
• 2013

본 연구에서는 열 구동 냉동사이클로서 유기 랭킨사이클 (ORC)과 증기 압축 냉동사이클(VCC)의 복합 사이클에 대한 엑서지 해석을 수행하였다. 시스템의 열원으로는 다양한 재생 에너지 열원이나 산업체에서의 폐열 등 현열 형태의 저온 열원을 고려하였으며 작동유체로서 R143a, R22, R134a, 프로판, 이소부탄, 부탄, R245fa 및 R123 등 여덟가지 작동유체들을 고려하였다. 터빈 입구 압력의 변화나 작동유체의 종류에 따라 시스템의 COP 나 엑서지 효율은 물론 시스템의 각 요소에서의 엑서지 파괴 (아너지)에 미치는 다양한 영향에 대해 분석하고 논의하였다. 해석 결과는 주어진 열원 온도에 대해 시스템에서 가장 엑서지 파괴가 큰 구성 요소는 터빈 입구 압력과 작동유체에 따라 민감하게 변화하는 사실을 보여준다.

• 한국HCI학회:학술대회논문집
• /
• 한국HCI학회 2008년도 학술대회 2부
• /
• pp.629-633
• /
• 2008

한국 사회에서 동영상 컨텐츠와 UCC 는 새로운 문화 현상이면서 광고 도구로써 많은 기대를 받고 있는 동시에 한편으로 수익성 모델 부재 및 저작권 등의 문제를 안고 있다. 이에 본 연구는 동영상 컨텐츠 및 UCC 사용자들의 유형을 파악함으로써 UCC 서비스의 성격이 무엇인가를 확인하면서, UCC 서비스가 소비자 에게 유의미한 상품의 하나로 수용되는 기제를 설명하고자 한다. 연구 대상이 된 사이트는 국내 대표적인 UCC 사이트이자 개인 방송국 서비스 제공하는 포탈이다. 연구방법은 사용자들이 보이는 활동을 기준으로 사용자들을 구분하고, 이를 통해서 각 사용자 유형이 보이는 주요 이용 행동 특성과 핵심 가치를 탐색하였다. 총 96개의 사용 행동 문항을 사용하였으며 연구참여자는 39명이었다. 분석 결과 라이브 동영상 서비스의 특성을 가진 UCC 서비스의 경우, '깍쟁이', 'B급 연예인', '시청자', '야심가', '휴머니스트', '패리스 힐튼' 총 6유형의 사용자집단이 있다는 것을 확인하였다. 각각의 사용자유형은 동영상 컨텐츠를 각기 다른 방식으로 활용할 뿐 아니라 동영상 서비스에 부여하는 가치도 달랐다. 본 연구는 동영상 컨텐츠나 UCC 시장에서 핵심 소비자이 누구이며, 이것을 기반으로 유의미한 비즈니스 모델을 설정할 수 있는 전략 포인트를 제공할 수 있을 것이다.