Min-Soo Jung

Silicon carbide-based hydrogen gas sensors for high-temperature applications.

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

A study on fast JCVM with new transaction mechanism and caching-buffer based on java card objects with a high locality

Java Card is now a mature and accepted standard for smart card and SIM technology. Java Card is distinguished primarily by its independence from hardware platforms and portability and is now the most important open standard. However, the main concern of Java Card is now its low execution speed caused by the hardware limitation. In this paper, we propose how to improve a execution speed of Java Card by reducing the number of EEPROM writing. Our approaches are an object-buffer based on a high locality of Java Card objects, the use of RAM, has a speed more faster 1000 times than EEPROM, as much as possible and new transaction mechanism using RAM.

A study on an efficient pre-resolution method for embedded Java system

Java has been recognized as an attractive language and platform to program embedded systems. Its not appropriate to apply class files in standard Java to embedded Java with the memory and processor limitation of embedded Java. In this paper, we propose an efficient method that can reduce execution time by using pre-resolution to convert symbolic references information to real addresses before executing of bytecode in target device. We examined 13 class files to know the sizes of the constant pool elements in the class file. Our pre-resolution, it reduces the overall memory footprint to about 87% of their original size. Additionally, it reduces a reference count of memory.

A Study on Electronic-Money Technology Using Near Field Communication

Recently, NFC (Near Field Communication) and its related technologies are being loaded into smartphones. Consequently, payment and data exchange are easily made through NFC. However, smartphone can be permitted an attack such as a user impersonation by exposure to information in the communication process. Therefore, the communication between mobile devices in NFC environments must be made safely with leaving any information at the other party. Moreover, it should be light-weight for wireless communication. In this paper, we propose an authentication method and a scheme of key agreement that can reduce the weight by using a hash function and XOR operation algorithms for mobile payment systems. We confirm that the proposal method leaves no information at the other party.

Study of an Improved AKA Protocol Based on the SIM Card

In addition to existing voice call service, the GSM platform has evolved to include various multimedia services and 3G services enabling international roaming. On that ground, safe data transmission and receiving technology and protection of privacy have become the key elements for the GSM service. However, many researchers have pointed out the problems inherent to the security algorithm and protocol for safe data communication using GSM. In this paper, we would like to analyze the security problems associated with the 2nd and 2.5th GSM network environment and consequently propose a security protocol providing safe services in the third generation network environment as well as the second generation network environment. The newly proposed security protocol may provide significantly strengthened security by allowing authentication of SIM users between SIM and ME and authentication among SIM/ME/AuC as well as reduced complexity in key agreement.

The research on how to reduce the number of EEPROM writing to improve speed of java card

Java Card technology enables smart cards and other devices with very limited memory to run small applications, called applets. It provides users with a secure and interoperable execution platform that can store and update multiple applications on a single device. This Java Card technology is now a mature and accepted standard smart card standards and SIM technology. However, the main concern of Java Card is now its low execution speed caused by the hardware limitation. In this paper, we propose several ideas about how to improve an execution speed of Java Card. The key idea of our approach is that an EEPROM writing operation is more expensive than that of RAM. We suggest how to use RAM as much as possible; Transaction_In_RAM(TrIR), Resolution_In_RAM and Java Object-buffer.

A Study on the Optimization of Class File for Java Card Platform

The Java Card technology enables programs written in the Java programming language to run on smart cards and other resource-constrained devices. Smart cards represent one of the smallest platforms in use today. The memory configuration of a smart card is limited. The greatest challenge of Java Card technology design is to fit Java system software in smart card while conserving enough space for applications. The solution is to support a subset of the features of the Java language and to apply a split model to implement the Java virtual machine and to optimize Java bytecode. In this paper, we describe in detail the optimization algorithm of Java bytecode.

A Study on Secure Chip for Message Authentication between a Smart Meter and Home Appliances in Smart Grid

Recently, a number of studies are underway about the smart grid for the demand what efficient power management. For these power management in smart grid environments, there are required a system that it can be safely stored and sent various information. In this paper, the user oriented side will be discussed from among the systems that it can be controlled and managed these power. There are devices of various types in the home environments which user live. And it is sent and received all power information as these modules are connected on the smart meters. In this process, it is possible an impersonation attack and a data forgery attack. In this paper, we analyze the security requirements in earlier smart grid environments and then also, propose a certification structure and a secure chip design for efficient message authentication between a smart meter and home appliances.

A novel buffer cache scheme using java card object with high locality for efficient java card applications

Java Card technology enables smart cards and other devices with very limited memory to run small applications. It provides users with a secure and interoperable execution platform that can store and update multiple applications on a single device. However, a major difficulty with Java Card is its low execution speed caused by hardware limitations. In this paper, we propose a novel scheme about how to improve the execution speed of Java Card. The key idea of our approach is a buffer cache scheme that uses RAM instead of EEPROM to improve the execution speed of Java Card. The proposed scheme reduces I/O count, especially EEPROM writing. Our scheme is based on the high locality of Java Card objects and the use of RAM that is several magnitude faster than EEPROM.

A study on how to reduce time and space by redefining new bytecode for Java card

One of the most serious problems of smart card system such as Java card, is about an amount of insufficient memory. Moreover, most of the embedded devices with Java VM support the post-issuance of new applications. These applications are usually stored in the memory, which is usually EEPROM. The key idea of our approach is to reduce the size of CAP file by grouping byte-codes. With our approach, the size of CAP file is reduced over 10% than that of typical CAP file. The size reduction of CAP file means that more available space of EEPROM in Java Card. It also enables an application to be downloaded more quickly in the case of an application sent to a mobile phone via the GSM network.