On server startup hibernate is altering table by adding new columns

Question

On server startup hibernate is altering table by adding new columns. When It prints in console that "schema update complete" table is altered.!

I have a table which has few fields of Number type. But when i am starting my tomcat from eclipse, hibernate is altering my table by adding new columns of same name of datatype float.

What is the root cause behind this

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "EPAMRT_BUC_COSTS_ARRAY") 
public class EPAMRTBucCostArray {

@Id
@GeneratedValue
private Integer BUC_COSTS_ARRAY_ID;
@Column(name= "BUC_CODE")
private String BUC_CODE;  
@Column(name= "BUC_DESC")
private String BUC_DESC;   
@Column(name= "BUC_AMOUNT")
private BigDecimal BUC_AMOUNT;  
@Column(name= "MTD_BUC")
private BigDecimal MTD_BUC;   
@Column(name= "YTD_BUC")
private BigDecimal YTD_BUC;  
@Column(name= "UNAMRT_BUC")
private BigDecimal UNAMRT_BUC;

public Integer getBUC_COSTS_ARRAY_ID() {
    return BUC_COSTS_ARRAY_ID;
}
public void setBUC_COSTS_ARRAY_ID(Integer bUC_COSTS_ARRAY_ID) {
    BUC_COSTS_ARRAY_ID = bUC_COSTS_ARRAY_ID;
}
public String getBUC_CODE() {
    return BUC_CODE;
}
public void setBUC_CODE(String bUC_CODE) {
    BUC_CODE = bUC_CODE;
}
public String getBUC_DESC() {
    return BUC_DESC;
}
public void setBUC_DESC(String bUC_DESC) {
    BUC_DESC = bUC_DESC;
}

public BigDecimal getBUC_AMOUNT() {
    return BUC_AMOUNT;
}
public void setBUC_AMOUNT(BigDecimal bUC_AMOUNT) {
    BUC_AMOUNT = bUC_AMOUNT;
}
public BigDecimal getMTD_BUC() {
    return MTD_BUC;
}
public void setMTD_BUC(BigDecimal mTD_BUC) {
    MTD_BUC = mTD_BUC;
}
public BigDecimal getYTD_BUC() {
    return YTD_BUC;
}
public void setYTD_BUC(BigDecimal yTD_BUC) {
    YTD_BUC = yTD_BUC;
}
public BigDecimal getUNAMRT_BUC() {
    return UNAMRT_BUC;
}
public void setUNAMRT_BUC(BigDecimal uNAMRT_BUC) {
    UNAMRT_BUC = uNAMRT_BUC;
}
}

when the schema update is completed there are 4 columns which are getting added are MTD_BUC, YTD_BUC, UNAMRT_BUC and BUC_DESC

previously my table was:

• BUC_COSTS_ARRAY_ID NUMBER(22 , 0),
• BUC_CODE VARCHAR2(10),
• BUC_DESC VARCHAR2(30),
• BUC_AMOUNT NUMBER(22 , 0),
• MTD_BUC NUMBER(22 , 0),
• YTD_BUC NUMBER(22 , 0),
• UNAMRT_BUC NUMBER(22 , 0)

Modified by hibernate:

• BUC_COSTS_ARRAY_ID NUMBER(22 , 0),
• BUC_CODE VARCHAR2(10),
• BUC_DESC VARCHAR2(30),
• BUC_AMOUNT NUMBER(22 , 0),
• MTD_BUC NUMBER(22 , 0),
• YTD_BUC NUMBER(22 , 0),
• UNAMRT_BUC NUMBER(22 , 0)
• BUC_DESC VARCHAR2(255),
• MTD_BUC NUMBER(19 , 2),
• UNAMRT_BUC NUMBER(19 , 2),
• YTD_BUC NUMBER(19 , 2)