The purpose of this study is to evaluate the efficacy and safety of wound sizing and completeness in chronic window treatment, and to confirm the superiority of area reduction in CG Paste and form-dressing as compared to form-dressing alone groups and CG Paste and form-dressing companion groups.

wound refers to a condition in which the skin is damaged by a cause. In general, open wound rather than closed wound requires active treatment. It is important to make sure that the wound are cured early and through proper treatment. If the wound is open for a long time, secondary complications such as infection can occur and are easy to transition to chronic wound. Chronic wound refers to an idea that does not heal after a period of time after a normal wound healing process, which is usually defined as if it does not heal for more than three to four weeks. 1. These chronic wound include diabetic foot ulcer, pressure ulcer, vascular ulcer, etc. In addition, with the recent aging of the population, the proportion of elderly patients increases, and the proportion of chronic wound where even simple surgical wound does not heal normally, resulting in increased expenditure on health care and decreased quality of life for patients.

Biotechnical dermal transplantation material, including acellular dermal matrix, are known to be more effective in wound healing than conventional wound treatments.

The mechanism of action of acellular matrices including acellular dermal matrix, is as follows: 1) it functions as a support for cell growth and granulation tissue formation, 2) has receptors capable of attaching to fibroblasts, 3) induction of angiogenesis, 4) chemoattractant activity of vascular endothelial cells, 5) role of providing various growth factors, and temporary storage function.

Unlike other products generally known as CG paste, the acellular allo-dermal matrix product to be used in this study is made into a paste type for ease of use after freeze-drying and granulation process after undergoing the process of degreasing of the same kind of dermis . Conventional sheet-type products can not be applied to curved wounds, they must be cut and rehydrated during use, while CG paste is easy to apply to curved wounds and can be applied directly to the desired wound area without rehydration It is expected to be a ready-to-use product with similar clinical effects to existing acellular allo-dermal matrix.

The purpose of this study is to evaluate the efficacy and safety of wound sizing and completeness in chronic window treatment, and to confirm the superiority of area reduction in CG Paste and form-dressing as compared to form-dressing alone groups and CG Paste and form-dressing companion groups.

Inclusion Criteria:

• Adults over 19 years
• Patients with skin defect from full-thickness skin defect to bone exposure level after debridement of wound
• Chronic wounds that have not been healed despite adequate treatment for more than 3 weeks after wounding
• At the time of the study, patients with a wound size of 4 cm 2 or more

Exclusion Criteria:

• Patients with superficial or partial thickness skin defect
• osteomyelitis patient
• An undermining wound, tunneling wound, which can not measure the exact depth, can be used if the wound is open wound due to debridement of wound.
• Patients who exceeded 12% of HbA1c within 3 months before participating in the study
• Patients with serum creatinine concentration of 3.0 mg / dL or more within 30 days before the study
• Patients who have applied other medical devices and growth factors for wound healing within 30 days before participating in the study
• Patients with lesion infections (available after infection treatment)