A.Y. CHEUNG ASSOCIATES, INC.

                      ARTICLES OF AMENDMENT AND RESTATEMENT


         A.Y.  CHEUNG  ASSOCIATES,  INC.,  a  Maryland  corporation,  having its
principal  office at 5026 Herzel Place,  Suite 101,  Beltsville,  Maryland 20705
(hereinafter  referred to as the  "Corporation"),  hereby certifies to the State
Department of Assessments and Taxation of Maryland that:

         FIRST:  The  Corporation  desires to amend and  restate  its Charter as
currently in effect as hereinafter  provided.  The provisions set forth in these
Articles of Amendment and  Restatement  are all the provisions of the Charter of
the Corporation as currently in effect.

         SECOND:  The Charter of the Corporation is hereby  amended  by striking
in their entirety Articles FIRST through EIGHTH,  inclusive, and by substituting
in lieu thereof the following:

     FIRST:  The  name of the  corporation  (which  is  hereinafter  called  the
"Corporation") is:

                            CHEUNG LABORATORIES, INC.

     SECOND: The purposes for which the Corporation is formed are as follows:

     (a) To carry on the business of a system engineering  company  specializing
in the application of  electromagnetic energy for  scientific,  industrial,  and






medical  markets and,  without  limiting the  generality  of the  foregoing,  to
manufacture,  prepare for market, buy or otherwise  acquire,  sell, or otherwise
deal in or with,  import,  export  and  transport,  at  wholesale  or  retail or
otherwise,  devices relating thereto; and to engage in any other lawful business
or activity. 

     (b) To do  anything  permitted  by Section  2-103 of the  Corporations  and
Associations Article of the Annotated Code of Maryland,  as amended from time to
time.

The foregoing  enumerated  purposes  shall be in no way limited or restricted by
reference  to, or inference  from,  the terms of any other clause of this or any
other Article of the Charter of the  Corporation,  and each shall be regarded as
independent;  and they are  intended to be and shall be  construed  as powers as
well as purposes and shall be in addition to and not in limitation of the powers
of corporations under the laws of the State of Maryland.

THIRD:  The  current  post  office  address  of  the  principal  office  of  the
Corporation in this State is 5026 Herzel Place, Suite 101, Beltsville,  Maryland
20705.  The name and address of the current resident agent of the Corporation is
Michael J.  Cromwell,  III, 10 Light Street,  Baltimore,  Maryland  21202.  Said
resident  agent is a  citizen  of the State of  Maryland  and  actually  resides
therein.

FOURTH: The total number of shares of stock of all classes which the Corporation
has authority to issue is 15,900,000 shares of common stock, with a par value of
$.01 per share, amounting in the aggregate to $159,000.

FIFTH:  The number of directors  of the  Corporation  shall be three (3),  which
number may be increased or decreased pursuant to the By-Laws of the Corporation,
but shall never be less than three (3). The names of the current directors,  who
shall act until their successors are duly chosen and qualified,  are:  Augustine
Y. Cheung; Fee-Wah Cheung; Vance Y. Hum.

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SIXTH:  The Board of  Directors  shall  manage the  business  and affairs of the
Corporation  and may  exercise  all the powers of the  Corporation  except those
conferred upon or reserved to the stockholders by law, including but not limited
to the following:

     (a) The Board of  Directors  shall  have the power from time to time and in
its sole  discretion:  (1) to  determine,  in accordance  with sound  accounting
practice, what constitutes annual or other net profits, earnings, surplus or net
assets in excess of capital; (2) to fix and vary from time to time the amount to
be reserved as working capital,  or determine that retained  earnings or surplus
shall remain in the hands of the Corporation;  (3) to set apart any funds of the
Corporation for the  establishment of such reserves in such amounts and for such
proper  purposes as it shall  determine and to abolish or  redesignate  any such
reserves or any part thereof;  (4) to determine whether there shall be declared,
distributed  or paid  any  distribution  or  dividend  in  stock,  cash or other
securities  or  property,  out of surplus or any other funds or amounts  legally
available  therefor,  and to declare,  distribute and pay the same at such times
and to the stockholders of record on such dates as it may from time to time deem
appropriate;  and (5) to determine  whether,  to what extent,  at what times and
places,  and under what  conditions  and  regulations  the books,  accounts  and
documents of the Corporation, or any of them, shall be open to the inspection of
stockholders,  except as otherwise  provided by statute or by the By-Laws,  and,
except as so provided,  no stockholder shall have the right to inspect any book,
account or document of the Corporation  unless authorized to do so by resolution
of the Board of Directors.

     (b) The Board of Directors of the  Corporation  shall have the power in its
sole discretion and without limitation, subject only to any restrictions imposed

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by  law,  to  authorize  the  issuance  from  time  to  time  of  shares  of the
Corporation's  stock,  with or without par value,  of any class,  whether now or
hereafter  authorized,   and  of  securities  convertible  into  shares  of  the
Corporation's  stock,  with or without par value,  of any class,  whether now or
hereafter authorized,  for such consideration (regardless of the value or amount
of such  consideration)  and in such  manner  and by such  means as the Board of
Directors may deem advisable.

     (c) The Board of Directors  shall have the power in its sole discretion and
without limitation, subject only to any restrictions imposed by law, to classify
or reclassify any unissued shares of stock, whether now or hereafter authorized,
by setting,  altering or eliminating  in any one or more respects,  from time to
time before the issuance of such shares,  any feature of such shares,  including
but not limited to the designation, par value, preferences,  conversion or other
rights,  voting powers,  qualifications,  and terms and conditions of redemption
of, and limitations as to dividends and any restrictions on, such shares.

         The  enumeration  and  definition of particular  powers of the Board of
Directors included in the foregoing provisions of this Article SIXTH shall in no
way be limited or restricted by reference to or inference  from the terms of any
other clause of this or any other Article of the Charter of the Corporation,  or
construed  as or deemed by  inference  or  otherwise in any manner to exclude or
limit any powers  conferred upon the Board of Directors under applicable law now
or hereafter in force.

SEVENTH:  No holders of any shares of the stock of the  Corporation of any class
shall have any preemptive right to purchase,  subscribe for or otherwise acquire
any shares of stock of the Corporation of any class now or hereafter authorized,
or any  securities  exchangeable  for or  convertible  into such shares,  or any
warrants or other  instruments  evidencing  rights or options to subscribe  for,
purchase or otherwise acquire such shares, other than such, if any, as the Board
of Directors in its discretion may fix.

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EIGHTH:  The  Corporation  reserves  the  right  from  time to time to make  any
amendments  of its Charter  which may now or  hereafter  be  authorized  by law,
including any amendments changing the terms or contract rights, as expressly set
forth  in  its  Charter,  of any of its  outstanding  stock  by  classification,
reclassification or otherwise, and any objecting stockholder whose rights may or
shall be  substantially  adversely  affected  shall not be  entitled to the same
rights as an objecting stockholder in the case of a consolidation, merger, share
exchange or sale, lease, exchange or transfer of all or substantially all of the
assets of the Corporation.

NINTH: The duration of the Corporation shall be perpetual.

     THIRD:  By  written  informal  action  unanimously  taken  by the  Board of
Directors  of  the  Corporation,  pursuant  to and in  accordance  with  Section
2-408(c) of the Corporations  and Associations  Article of the Annotated Code of
Maryland,  the Board of Directors of the Corporation  duly advised the foregoing
Articles  of  Amendment  and  Restatement   and,  by  written   informal  action
unanimously  taken by the  stockholders of the  Corporation,  in accordance with
Section 2-505 of the Corporations and Associations Article of the Annotated Code
of Maryland,  the stockholders of the Corporation duly approved said Articles of
Amendment and Restatement.

     FOURTH:  (a) The total  number of  shares  of all  classes  of stock of the
Corporation  heretofore  authorized  is 5,000  shares of common stock all of one
class. Such shares are without par value.

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     (b) The total  number of shares of all classes of stock of the  Corporation
as increased is 15,900,000  shares of common stock all of one class. Such shares
have a par value of $.01 per share, amounting in the aggregate to $159,000.

         FIFTH:  Upon the  effectiveness  of these  Articles  of  Amendment  and
Restatement  with the State  Department of Assessments and Taxation of Maryland,
each of the authorized shares of common stock without par value shall be changed
and split on the basis of three  thousand one hundred  eighty  (3,180) shares of
common  stock  with a par  value of $.01 per share for each  share  without  par
value,  provided  that any  fractional  interest  shall be  eliminated  by being
rounded off to a full share of stock.

     IN WITNESS WHEREOF, A.Y. CHEUNG ASSOCIATES,  INC. has caused these presents
to be signed in its name and on its behalf by its  President  and its  corporate
seal to be  hereunder  affixed and attested by its  Assistant  Secretary on this
_____ day of June, 1996, and its President  acknowledges  that these Articles of
Amendment and Restatement are the act and deed of A.Y. CHEUNG  ASSOCIATES,  INC.
and, under the penalties of perjury, that the matters and facts set forth herein
with respect to authorization  and approval are true in all material respects to
the best of his knowledge, information and belief.

ATTEST:                                     A.Y. CHEUNG ASSOCIATES, INC.
_______________________________     By: _________________________________
Vance Y. Hum, Assistant Secretary           Augustine Y. Cheung, President

[SEAL]

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