초록 ▼

○ 연구결과
- 분말식품의 마이크로파 유전특성 측정방법을 개발하고 밀가루, 커피, 분유의 수분함량, 산물밀도, 온도 등에 따른 마이크로파 유전특성을 구명하였다.
- 마이크로파 전파특성을 이용하여 분말식품의 수분측정에 적합한 주파수를 구명하였다.
- 분말식품의 수분측정에 적합한 마이크로파 패치 어레이 안테나, 발진기, 아이솔레이터, 디텍터 등을 개발하고 평가하였다.
- 마이크로파 투과법을 이용하여 2.0㎓, 7.0㎓, 10.5㎓ 마이크로파 다중주파수 측정시스템을 개발하여 시료이송이 가능한 컨베이어 시스템, 온도측

○ 연구결과
- 분말식품의 마이크로파 유전특성 측정방법을 개발하고 밀가루, 커피, 분유의 수분함량, 산물밀도, 온도 등에 따른 마이크로파 유전특성을 구명하였다.
- 마이크로파 전파특성을 이용하여 분말식품의 수분측정에 적합한 주파수를 구명하였다.
- 분말식품의 수분측정에 적합한 마이크로파 패치 어레이 안테나, 발진기, 아이솔레이터, 디텍터 등을 개발하고 평가하였다.
- 마이크로파 투과법을 이용하여 2.0㎓, 7.0㎓, 10.5㎓ 마이크로파 다중주파수 측정시스템을 개발하여 시료이송이 가능한 컨베이어 시스템, 온도측정부, 회전속도계로 구성된 온라인 측정 시스템에 적용하였다.
- 온라인 수분측정 시험 데이터를 이용하여 분말식품에 적합한 수분측정 모델을 개발하기 위하여 다중선형획귀분석, 주성분회귀분석, 인공신경망 모델을 개발하고 평가하였다.
- 분밀식품 수분함량 무선계측시스템을 개발하였으며 개발된 기술들을 활용하여 상업화를 시작품을 개발하였다.

Abstract ▼

Ⅳ. Results and Suggestions to the Practical Applications
[Dielectric property of powdered food and development of on-line measurement system for moisture content (Korea Research Institute of Standards and Science)]
1. Measurement of dielectric property of powdered food at microwave frequencies

Ⅳ. Results and Suggestions to the Practical Applications
[Dielectric property of powdered food and development of on-line measurement system for moisture content (Korea Research Institute of Standards and Science)]
1. Measurement of dielectric property of powdered food at microwave frequencies
1) Microwave free-space transmission technique was used to measure the dielectric property of powdered food at microwave frequencies. The sample holder at which microwaves ranging from 1 to 15 GHz can transmit was designed and fabricated. From the microwave propagation theory the equation expressing the dielectric property of powdered food was derived and validated by standard dielectrics.
2) The dielectric property of powdered food such as wheat flour, coffee powder and milk powder was measured and analyzed. In the uniform range of bulk density of material, the real parts of permittivity of the food samples increased with the increased of moisture content, bulk density and temperature of the food sample.
3) The propagation properties such as attenuation and phase shift increased linearly as the moisture density of the food samples increased. As a measuring frequency, the X-band was recommended.
2. On-line measurement system for moisture content of powdered food
1) The microwave multiple frequencies system with 2.5 GHz, 7.0 GHz, and 10.5 GHz frequencies was developed. That microwave system consisted of oscillators, isolators, transmitting and receiving patch antennas, detectors, power amplifies. The output voltage of microwave measurement system due to the change of moisture content in food samples was measured and analyzed.
2) The on-line measurement system consisting of microwave system, conveying system, inlet and outlet devices of food sample, plate to control the thickness of food sample, temperature sensing unit, taco-meter, and central processing unit having analog to digital converter and microprocessor was constructed.
3. Development of measurement model for moisture content of powdered food
1) As powdered food samples, wheat flour, coffee powder and milk powder were used and their ranges of moisture content were 7 to 15%w.b., 1 to 8%w.b. and 1 to 16%w.b., respectively. The output voltages of microwave measurement system due to the moisture content, sample temperature and sample moving speed were measured and analyzed.
2) The coefficients of correlation between moisture content of food samples and output voltage of microwave measurement system were higher than 0.9. The output voltage of microwave measurement system increased as the sample temperature increased.
3) Various calibration models for moisture content of powdered food were developed by using multiple linear regression, principal component regression, and artificial neural network. The artificial neural network model showed best results but the multiple linear regression model also showed good results. The developed artificial neural network consisted of 3 layers having input, hidden and output layers and the optimal node number of hidden layer was obtained. Considering the construction of commercial type moisture, we selected the multiple linear regression equation with three independent variables such as sample temperature, frequencies as a calibration equation for moisture content of powdered food.
4. Development of wireless measurement system for moisture content
The wireless measurement system for moisture content of powdered food was developed. That system consisted of data processing unit with 4-sensor input channels and analog to digital converter, transmitting unit with micro-controller, and receiving unit. The received moisture content of powdered food by receiving unit was transferred to the main computer via RS232C serialcommunication port and hence the real time monitoring of the moisture content is possible. Finally the commercial type moisture meters including wireless measurement system were developed.
[Development of microwave sensor and circuits (Kwangun University)]
1. Development and evaluation of microwave antenna for moisture content measurement
As a moisture sensor, the microstrip 2×2 patch array antennas were developed and evaluated at 7.0 and 10.5 GH. The patch antenna was developed on the Teflon substrate of which permittivity, hight and thickness of copper are 2.6, 0.54mm, and 0.018 respectively. The beam patterns of the developed patch array antenna were measured. The half beamwidths of two patch array antennas were higher than 50 degree and hence it is useful for applying to microwave type moisture meter.
2. Development and evaluation of circuits for moisture content measurement
1) The 7.0 GHz and 10.5 GHz dielectric resonator type oscillators for microwave type moisture meter were designed and fabricated. The output powers of the fabricated oscillators at 7.0 GHz and 10.5GHz are 11dBm and 10dBm, respectively and hence it was concluded that the fabricated oscillators were good for microwave type moisture meter
2) As relating circuits, the isolators with circulator to protect the oscillator, power amplifiers to amplify the output power of the oscillator, detector to convert the RF signal to d-c level were developed at 7.0 GHz and 10.5 GHz.
With the combinations of the developed all microwave circuit components, the microwave free-space transmission type measurement system was finally constructed.

목차 Contents

• 표지 ... 1
• 제출문 ... 2
• 요약문 ... 3
• SUMMARY ... 8
• CONTENTS ... 14
• 목차 ... 16
• 제 1 장 연구개발과제의 개요 ... 18
• 제 1 절 연구개발의 필요성 ... 18
• 제 2 절 연구개발의 목표 및 내용 ... 20
• 제 2 장 국내외 기술개발 현황 ... 21
• 제 3 장 연구개발 수행내용 및 결과 ... 23
• 제 1 절 분말식품의 마이크로파 유전특성 측정 ... 23
• 1. 분말식품 제조공정 분석 ... 23
• 2. 상용화된 수분함량 측정장치 장단점 분석 ... 25
• 3. 분말식품의 마이크로파 유전특성 측정 ... 26
• 4. 요약 및 결론 ... 52
• 제 2 절 수분측정용 마이크로파 장치 개발 ... 54
• 1. 마이크로파 능동소자 ... 54
• 2. 회로설계·제작 및 측정결과 ... 104
• 3. 요약 및 결론 ... 136
• 제 3 절 온라인 수분측정장치 개발 및 수분측정 모델 개발 ... 137
• 1. 서론 ... 137
• 2. 마이크로파 다중주파수 측정시스템 개발 ... 138
• 3. 온라인 수분측정 실험 및 결과분석 ... 154
• 4. 수분측정 모델 개발 ... 159
• 5. 요약 및 결론 ... 184
• 제 4 절 무선 계측시스템 및 상용화 제품 개발 ... 187
• 1. 무선 계측시스템 제작 ... 187
• 2. 상용화를 위한 시작품 개발 ... 190
• 3. 요약 및 결론 ... 194
• 제 4 장 목표달성도 및 관련분야에의 기여도 ... 195
• 제 1 절 연구개발 목표 달성도 ... 195
• 제 2 절 대외 기여도 ... 197
• 제 5 장 연구개발결과의 활용계획 ... 198
• 제 6 장 연구개발과정에서 수집한 해외과학기술정보 ... 199
• 제 7 장 참고문헌 ... 200
• 부 록 : Data sheet ... 203
• 1. 유전체 공진기 ... 203
• 2. 전력증폭기용 소자 ... 207
• 3. 검파기 ... 210
• 4. 아이솔레이터 ... 212
• 끝페이지 ... 213