Carbon dioxide enrichment for greenhouse crops has generally been a standard commercial practice for many years. Vegetable crops such as tomato, cucumber, and lettuce respond positively to the CO2 enrichment. But improper CO2 enrichment leads to physiological damage and economical loss. This study was carried out to develop a CO2 concentration control algorithm considering growth stage and efficiency. The measurand was CO2 consumption rate and top fresh weight that represents growth stage. The weight of top fresh lettuce as a whole in the tray was measured through a non-destructive method. The demand in CO2 concentration according to growth stage was investigated. The results are summarized as follows. 1. The CO2 consumption rate could be measured within the error of ± 15.4mgCO2/hr in the range of CO2 concentration of 500-1500ppm. 2. The weight of top fresh lettuce could be measured within the error ± 4.3g in the range of 0-1400g. 3. The CO2 control model developed could determine an economical CO2 supply rate considering CO2 consumption rate and leakage rate. 4. The CO2 control algorithm based on the control model was composed of feedforward control for maintaining a stable CO2 concentration level, and feedback control with CO2 consumption rate and top fresh weight for adapting to the change in CO2 demand by growth stage. 5. For the performance test with the developed control algorithm on lettuce the decrease in CO2 supply rate was obtained without a significant decrease in top fresh weight.

16비트 마이크로 프로세서를 이용하여 계측.제어용의 계산기를 시험제작한 결과 다음과 같은 결론을 얻었다. 1) 본 장치는 필요 최소한의 부품만을 요구하므로 고도의 수학적인 계산능력보다 속도의 신속성이 요구되는 계측이나 제어에 저렴한 가격으로 응용될 수 있다. 2) Stand by current 만을 공급하는 기법을 동원하여 자기 디스크나 테이프 레코오더의 도움없이도 데이터를 저장할 수 있었다. 3) 본 장치는 매우 간단한 관계로 주변장치의 의한 제약조건이 적어서 계측.제어의 응용에 매우 적합하다.