Field Programmable Gate Array (FPGA) is an important component for modern digital systems. FPGA is a semi-custom integrated circuit for implementing arbitrary logic functions of users by using look-up tables. FPGA has two main resources. One is logic resource and the other is interconnect resource. The logic resources implement the logic functions of user circuits and the interconnect resources connect logic resources to each other. Logic resource includes look-up table, flip-flop and multiplexer, and a net is an example of interconnect resource. When you write the user circuit into FPGA, FPGA is said to be configured. It is possible to write circuits into FPGA several times, i.e., FPGA has reconfigurability.

FPGA test is a processing for finding out whether there is a fault in FPGA’s resources or not, while FPGA diagnosis is for finding out what fault is in which resource of FPGA. There are two methods for testing and diagnosing FPGAs. One is application-independent method and the other is application-dependent method. The application-independent method can test all resources of FPGA, and the application-dependent method can test only the resources used in the circuit mapped into FPGA.

Factories increase the manufacturing yield of FPGAs by performing application-dependent tests and diagnoses. Application-dependent tests and diagnoses of FPGAs are also important to users because there may be FPGAs that have not passed application-independent tests. In FPGAs, the interconnect resource occupies more chip area than other resources. Therefore, faults in FPGA are mostly interconnect faults.

Two methods have been mainly employed for application-dependent tests and diagnoses of interconnect faults of FPGA. These previous methods are all for testing and diagnosing interconnect of circuits with look-up tables and flip-flops when mapped into FPGA. The circuits mapped into FPGA often include multiplexers in addition to look-up tables and flip-flops. The previous methods are not enough for testing and diagnosing the interconnect of circuits that include multiplexers when mapped into FPGA because the function of multiplexers cannot be changed arbitrarily, unlike look-up tables.

Son Yong Jun, a researcher at the Faculty of Electronics, has proposed a new method for diagnosing interconnect faults of circuits with multiplexers when mapped into FPGA.

This method is an application-dependent method for diagnosing only interconnects of FPGA used in circuits. What is special about this method is to use the hierarchical structure of multiplexers and a single-term function.

The proposed method can be applied to diagnosing any single stuck-at fault and bridging fault in the net of circuits comprised of look-up tables and multiplexers.

Horse riding is a sports event to decide who rides faster on horseback and who performs more spectacular stunts on horseback.

Our country has a very long history of using horses. The Koreans have bred many horses of native kinds suitable for breeding in the mountainous and rugged terrain of the country since long time ago.

The excellent riding skills of the ancestors were inherited and developed at a high level, with such contents as handling weapons and hurdling on horseback being added to them. The best horse riders in the history of the country were the Koguryo people.

The technical contents of horse riding include preparation for horse riding, methods of mounting and dismounting a horse, standard sitting position, learning how to ride at a walking pace, quick pace and gallop and others.

Horsemanship is particularly conspicuous in horse riding.

It is literally performing stunts on horseback, including those of standing on a running horse, turning over from one side to the other by holding the saddle and dragging feet on the ground by clinging to the horse.

As the country has full conditions for horse riding good for health, the enthusiasm for riding is steadily growing stronger among working people, youth and children.

Composite shell structures with varying thickness are often used in different industrial fields because it could exhibit structural advantages at minimum material cost.

Recently, many works have been reported for static and dynamic analyses of different structures with variable thickness. Various methods such as Haar wavelet method, Jacobi-Ritz method spectral-Tchebychev method, dynamic stiffness method, finite element method and meshfree method have been employed for numerical analysis of composite structures. In recent years, the meshfree method has attracted significant attention of many scholars.

Jo Ju Chol, a researcher at the Faculty of Mechanical Science and Technology, developed a meshfree Jacobi-radial point interpolation (Jacobi-RPI) method for free vibration and stochastic response analyses of laminated composite sectorial and annular plates with straight fibers and variable thickness.

First, he adopted the Hamilton’s principle to establish the equations of motion of the laminated composite sectorial plate with straight fiber and variable thickness in the framework of first-order shear deformation theory (FSDT). Then, he approximated the displacement components of the plate by using the meshfree Jacobi-RPI shape function. As the laminated annular plate with straight fiber is not symmetrical, he obtained its motion equations by combining the equations of several sectorial plates.

He validated the accuracy and reliability of the proposed method through a sufficient number of numerical studies.

For more details, you can refer to his paper “A meshfree formulation for free vibration and stationary stochastic response analyses of laminated composite annular plate with straight fibers and variable thickness” in “Acta Mech” (SCI).