• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1899-1911
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• 2018

In this work, we propose a concurrency control scheme in object-oriented database (OODB). Since an OODB provides complex modeling power than the conventional relational databases, a concurrency control technique in OODB is also rather complicated and has influence on the overall performance. Thus, it is very important to develop a concurrency control technique with less overhead. The proposed scheme deals with class hierarchy that is a key concept in OODBs. The proposed scheme is developed on implicit locking scheme. Also, the proposed scheme is designed using data access frequency in order to reduce locking overhead than implicit locking. It means that, if access frequency information is not available, the proposed scheme works just like the existing implicit locking, In our work, the correctness of the proposed scheme is proved. The performance is analyzed depending on access types. Also, it is proved that our scheme performs works much better than the implicit locking does.

• Journal of Internet Computing and Services
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• v.15 no.1
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• pp.63-71
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• 2014

Currently many non-traditional application areas such as artificial intelligence and web databases require advanced modeling power than the existing relational data model. In those application areas, object-oriented database (OODB) is better data model since an OODB can providemodeling power as grouping similar objects into class, and organizing all classes into a hierarchy where a subclass inherits all definitions from its superclasses. The purpose of this paper is to develop an OODB concurrency control scheme dealing with multiple inheritance. The proposed scheme, called Multiple Inheritance Implicit Locking (MIIL), is based on so-called implicit locking. In the proposed scheme, we eliminate redundant locks that are necessary in the existing implicit locking scheme. Intention locks are required as the existing implicit locking scheme. In this paper, it is shown that MIIL has less locking overhead than implicit locking does. We use only OODB inheritance hierarchies, single inheritance and multiple inheritance so that no additional overhead is necessary for reducing locking overhead.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2
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• pp.347-354
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• 2000

This paper presents the efficient mechanisms for concurrency control and writing authority control in collaborative writing system are represented by the tree structures which consist of the logical objects and the content objects connected to the terminal objects of trees. For concurrency control, we adopted the approach to extend the multiple-granularity-locking-scheme. This scheme allows us to lock any objects at each level of the hierarchy. We also defined the locking compatibility table by analysing the operations applicable to any objects at each level of the hierarchy. We finally suggest the extended-multiple-granularity-locking mechanism which uses the locking compatibilility table for deciding to lock an object. This scheme gives the benefit to maximize the possibility of concurrent accessing to the shared objects. In addition, we suggest a mechanism for writing authority control which prohibits the Non-Group users from modifying the shared objects based on the concept of Group/Non-Group The proposed mechanism allows us to protect copyright very reasonably.

• Journal of information and communication convergence engineering
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• v.3 no.1
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• pp.18-22
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• 2005

This paper presents the analog adaptive phase-locked loop (PLL) architecture with a new adaptive bandwidth controller to reduce locking time and minimize jitter in PLL output for wireless communication. It adaptively controls the loop bandwidth according to the locking status. When the phase error is large, the PLL increases the loop bandwidth and reduces locking time. When the phase error is small, the PLL decreases the loop bandwidth and minimizes output jitters. The adaptive bandwidth control is implemented by controlling charge pump current depending on the locking status. A 1.28-GHz CMOS phase-locked loop with adaptive bandwidth control is designed with 0.35 $mu$m CMOS technology. It is simulated by HSPICE and achieves the primary reference sidebands at the output of the VCO are approximately -80dBc.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1159-1168
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• 2012

Control Flow Integrity(CFI) and Control Flow Locking(CFL) prevent unintended execution of software and provide integrity in control flow. Attackers, however, can still hijack program controls since CFI and CFL does not support fine-granularity, context-sensitive protection. In this paper, we propose a new CFI scheme, Source-code CFI(SCFI), to overcome the problems. SCFI provides context-sensitive locking for control flow. Thus, the proposed approach protects software against the attacks on the previous CFI and CFL schemes and improves safety.

• Journal of Drive and Control
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• v.21 no.1
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• pp.1-7
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• 2024

The locking performance of a multi-plate clutch with a mechanical lock-up system is governed by the engagement algorithm. In this paper, a control algorithm to improve the locking performance of the clutch was studied. A 1D dynamic model was constructed and simulated according to the developed algorithm. The developed algorithm was composed of a method in which the locking device is engaged while generating artificial slip on the friction plate by controlling the piston pressure of the clutch. Furthermore, a case study of the parameters within the developed algorithm was conducted to explore combinations that maximize locking performance and analyze trends according to these parameters.

• Journal of Information Technology Applications and Management
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• v.11 no.1
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• pp.53-67
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• 2004

We propose an advanced transaction scheduling protocol to improve the concurrency and to guarantee the mobility for the mobile database management systems. Mobility, portability, and wireless link In mobile computing environment can cause certain drawbacks, and thus it is more difficult to solve the concurrency control problems. However, a locking scheme should be used to guarantee the data consistency and to prevent the data conflicts. It is well known that data consistency is guaranteed by standard transaction scheduling schemes like two-phase locking (2PL). It has two of operation, lock and unlock. But 2PL does not give solution for mobile system. Altruistic Locking (AL) and classifying transactions, we adapt, can give solution for the previous problems. AL, as an advanced protocol, has attempted to reduce delay effects associated with lock release moment by the use of donation. In this paper, we extend those approaches and classify the transactions to reduce delay effects of short-lived transaction caused by long-lived transaction. In addition, we show efficient solution for the case of disconnection occurrence. Our protocol, namely, Mobile Altruistic Locking (MAL) is shown to be efficiently used in order to reduce delay effects and to guarantee database consistency in a state of the slippery connection in mobile database systems.

• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.24-31
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• 2001

In this paper, we present an advanced transaction scheduling protocol to improve the degree of concurrency and satisfy the security requirements for multilevel secure database. We adapted two-phase locking protocol, namely traditional syntax-oriented serializability notions, to multilevel secure database. Altruistic locking, as an advanced protocol, has attempted to reduce delay effect associated with lock release moment by use of the idea of donation. An improved form of altruism has also been deployed for extended altruistic locking OffiLl. This is in a way that scope of data to be early released is enlarged to include even data initially not intended to be donated. We also adapted XAL to multilevel secure database and we first of all investigated limitations inherent in both altruistic schemes from the perspective of alleviating starvation occasions for transactions in particular of short-lived nature for multilevel secure database. Our protocol is based on extended altruistic locking for multilevel secure database (XAL/MLS), but a new method, namely two-way donation locking for multilevel secure database (2DL!/-MLS), is additionally used in order to satisfy security requirements and concurrency. The efficiency of the proposed protocol was verified by experimental results.

• Journal of KIISE:Databases
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• v.29 no.6
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• pp.464-476
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• 2002

Main-memory database systems which reside entire databases in main memory are suitable for high-performance real-time transaction processing. If two-phase locking(2PL) as concurrency control protocol is used for the transactions accessing main-memory databases, however, the possibility of lock conflict will be low but lock operations become relatively big overhead in total transaction processing time. In this paper, We designed a real-time static locking(RT-SL) protocol which minimizes lock operation overhead and reflects the priority of transactions and we implemented it on a main-memory real-time database system, Mr.RT. We also evaluate and compare its performance with the existing real-time locking protocols based on 2PL such as 2PL-PI and 2PL-HP. The extensive experiments reveal that our RT-SL outperforms the existing ones in most cases.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.1
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• pp.116-121
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• 2019

The LVDT (Linear Variable Displacement Transducer) type sensor used for the existing ship's steering gear is simple on / off that does not perform proportional control operation to the control & unloading device. When the main spool is located at both extremes, It is reflected in the price by using an expensive sensor for import. In this paper, the Hall Effect Sensor is applied to Hydraulic Locking Alarm to analyze classification rules, structure, characteristics and operation principle of valves, and research on localization development in terms of cost reduction. The comparative analysis of the existing prototypes and the cause analysis of the problems were carried out, and the structural analysis showed satisfactory results within the allowable stress range. In addition, it was verified through experiments that the actual operation is realized by applying the actual developed product, and it was confirmed that the load on the maximum value exceeds the allowable maximum load even in the case of the universal tensile test in preparation for the departure of the rod casing.