SG224CD-S8 케미컬용 pH 전극 SENSOREX pH Sensor SG224CD-S8 케미컬용 pH 전극 SENSOREX pH Sensor SG224CD-S8 케미컬용 pH 전극 SENSOREX pH Sensor SG224CD-S8 케미컬용 pH 전극 SENSOREX pH Sensor