Enhanced Sino-Russian Relations and Its Implications for the Security of South Korea

( Chang Hee Park ) 국방대학교 안보문제연구소 2008 The Korean Journal of Security Affairs Vol.13 No.2

This article analyzes the current development of Sino-Russian relations and its implications for the security of South Korea. Since the agreement of strategic partnership in 1996, China and Russia have had close relations through ratifying the agreement of borderline, promoting cooperation through the Shanghai Cooperation Organization, and invigorating arms trade. In July 2001, the two countries opened a new century concluding a new treaty to enhance their relations beyond the existing strategic partnership. Through their enhanced relations, China and Russia could promote common strategic interests to establish a multi-polar international order and to secure traditional spheres of influence in their peripheries. The security of South Korea can be best understood in this context. Even though South Korean-Chinese relations are improved, it does not necessarily mean that common strategic interests between them can be shared as much. That is, China may think of South Korea as a useful “strategic partner” to pursue its strategic interest vis-a-vie the United States, which is to promote a multi-polar world and to prevent its traditional sphere of influence from being eclipsed. Consequently, the strategic partnership between China and South Korea may not lie in common strategic interests, but in different interests on their own.

Failure Mode of Piezoelectric Sensor for Accelerated Life Test

Changhee Park,Hyun-Joong Hwang,Gyechun Cho,Chang-Ho Hong 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2

The high-level nuclear waste (HLW) repository is a 500-1,000 m deep geological disposal system with a very long life expectancy for disposing of high-level waste, which is known to have a half-life of several thousand years. This repository is subject to harsh environmental conditions, such as high temperature and radiation from high-level waste, that can cause deterioration and crack. When radiation escapes through cracks, it can injure persons on the ground. Therefore, it is essential to install a sensor that can detect problems such as cracks. But, since the high-level nuclear waste (HLW) repository is sealed with bentonite and backfill, the sensor cannot be removed or replaced once it has been installed. Therefore, it is necessary to develop a highly durable monitoring sensor that can withstand harsh environmental conditions. Before attempting to improve durability, it is first required to assess durability quantitatively. And an accelerated life test is a widely used method for assessing durability. However, it is important to obtain the same failure mode when conducting a reliability test, such as an accelerated life test. If the accelerated life test is conducted using different failure modes, the dependability of the results is inevitably diminished. Therefore, in this study, a representative failure mode for the piezoelectric sensor used in the accelerated life test was derived through experiments and literature research.

The Significance of Geopolitics In The U.S.-China Rivalry

( Chang Hee Park ) 국방대학교 안보문제연구소 2004 The Korean Journal of Security Affairs Vol.9 No.1

Geopolitics is the interaction between politics and geography, which geography in one way or another fundamentally conditions political process and behavior. In this article I elaborate the term geopolitics as spatial movements to expand [secure] one`s own sphere of influence for security vis-a-vis others. Throughout history, international peace and regional stability could be maintained only when great powers could recognize a competitor``s sphere of influence. Lots of historical cases have verified it. That is, if two or more expanding spheres of influence overlap, then possibility of conflict increases. The U.S.-China rivalry seems to be structural, which means neither side nor the third party can control its course toward a future collision. Despite some optimistic views on their relations since the September 11, the U.S. and China have endeavored to solve their security dilemma through competition for spatial movements rather than cooperation for common interest. Washington has continued a policy approach that appeared tougher toward Beijing, and has extended its military power deep into Southeast Asia, South Asia, and Central Asia. Even though U.S. policy could be explained as efforts to fight war on terrorism, it inevitably intruded China`s traditional sphere of influence. As a result, Beijing has become wary of the increased U.S. military presence in her vicinity, and has strived to enhance its influence on neighboring states to check U.S. moves toward its borders. Such actions and reactions ?have intensified mutual suspects on each other`s moves and intention. Without any clear understanding and concession for their own spheres of influence, the rivalry of the U.S. and China will necessarily cause serious conflicts in the future.

The Moving Photocarrier Grating (MPG) Technique for the Transport Properties of a-Se:As Films

Chang Hee Park,이광세,김정배,김재형 한국전기전자재료학회 2005 Transactions on Electrical and Electronic Material Vol.6 No.6

The moving photocarrier grating (MPG) technique for the determination of the carrier mobilities and the recombination lifetime of a-Se:As films has been studied. The electron and hole drift mobility and the recombination lifetime of a-Se films with arsenic (As) additions have been obtained from measurement of the short circuit current density as a function of grating velocity and spatial period. The hole mobility decreases due to defect density of hole traps when x exceeds 0.003, whereas the hole mobility increases for the case of low As addition . We have found an increase in hole drift mobility and recombination lifetime, especially when As with is added into the a-Se film.

Investigation of Radiation Effect on the HLW Repository Monitoring Sensors

Changhee Park,Sokpheanika Chea,Chang-Ho Hong,Jeonguk Bang,Gye-Chun Cho 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The high-level nuclear waste (HLW) repository disposes of high-level nuclear waste at a depth of 500 m to 1,000 m underground. Structural health monitoring must be accompanied by the complex environmental conditions of high temperature, high humidity, radiation, and mechanical stress. A thermocouple for measuring temperature, total stress meter and pore pressure meter for measuring stress and water pressure, relative hygrometer and electrical resistivity sensor (TDR or SUS) for measuring humidity, accelerometer for measuring crack signals, and strain gauge for measuring displacement are used. For safety, after disposing of HLW in the HLW repository, access to the disposal tunnel gets blocked, making it impossible to replace or remove the monitoring sensors. So, it is necessary to evaluate the effect of the HLW repository’s environmental conditions on the monitoring sensors and enhance their durability through quantitative life evaluation and shielding. Before evaluating the life of accelerometers and strain gauges used in the HLW repository, an experimental study is conducted to determine failure modes and failure mechanisms under radiation conditions, which are unique environmental conditions of the HLW repository.

Changing Balance of Forces in East Asia and India-Korea Defense Cooperation

( Changhee Park ) 경남대학교 극동문제연구소 2014 국제관계연구 시리즈 Vol.32 No.0

Average Current Mode Control for LLC Series Resonant DC-to-DC Converters

Chang Hee Park,Sung Ho Cho,Jinhaeng Jang,Syam Kumar Pidaparthy,Taeyoung Ahn,Byungcho Choi 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

An average current mode control scheme that consistently offers good dynamic performance for LLC series resonant DC-to-DC converters irrespective of the changes in the operational conditions is presented in this paper. The proposed control scheme employs current feedback from the resonant tank circuit through an integrator-type compensation amplifier to improve the dynamic performance and enhance the noise immunity and reliability of the feedback controller. Design guidelines are provided for both current feedback and voltage feedback compensation. The performance of the new control scheme is demonstrated through an experimental 150 W converter operating with 340 V to 390 V input voltage to provide a 24 V output voltage.

Why China attacks: China`s geostrategic vulnerability and its military intervention

( Chang Hee Park ) 한국국방연구원 2008 The Korean Journal of Defense Analysis Vol.20 No.3

This research deals with the puzzle of why China intervenes militarily in its neighboring countries, and attempts to explain China`s use of force. The paper will address four hypotheses related to China`s geostrategic vulnerability, and test the hypotheses through two case studies of the Korean War and the Sino-Vietnamese War. Then, as a conclusion, theoretical implications and future prospects for China`s use of force against its neighbors will be suggested. The author`s argument is that China`s geostrategic vulnerability caused its military interventions during the Cold War era. In geostrategic terms, its weakening capability to control a ````crucial space````――i.e. a neighboring state or a traditional sphere of influence, both of which are imperative for national security――was the main factor increasing China`s geostrategic vulnerability, because it resulted in antagonization of the neighboring states, the loss of its traditional spheres of influence, and the possibility of strategic encirclement by the strong powers. Whenever it felt vulnerable, China launched armed interventions against its neighbors to regain control over the crucial space and endeavored to shape a more favorable strategic environment to counter the threats of a major enemy.

A Count Model of Multi-Purpose Shopping Behavior

( Chang Hee Park ) 서암순창장학회 2017 Journal of Marketing Thought Vol.4 No.2

When a firm offers multiple services, customers are motivated to shop at the firm by different services over time. Once arriving at the firm, they often make not only planned purchases but also impulse purchases. Accordingly, for the development of an effective marketing strategy, it is important to consider what services drive customers’ shopping trips and what others are purchased on impulse. This research proposes a count model of purchase behavior that captures the effect of different services on motivating customers’ visit to a firm and accounts for their planned and impulse buying during the shopping trip.

Paradox of Strategy: Avoidance of a Decisive Battle and Strength for Defense

( Chang Hee Park ) 국방대학교 안보문제연구소 2005 The Korean Journal of Security Affairs Vol.10 No.1