• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1827-1840
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• 2001

In digital data transmission/storage systems, the compensation for channel distortion is conducted normally using a training sequence that is known a priori to both the sender and receiver. The use of the training sequences results in inefficient utilization of channel bandwidth. Sometimes, it is also impossible to send training sequences such as in the burst-mode communication. As such, a great deal of attention has been given to the approach requiring no training sequences, which has been called the blind equalization technique. On the other hand, to utilize the limited bandwidth effectively, the concept of partial response (PR) signaling has widely been adopted in both the high-speed transmission and high-density recording/playback systems such as digital microwave, digital subscriber loops, hard disk drives, digital VCRs and digital versatile recordable disks and so on. This paper is concerned with blind adaptive equalization of partial response channels whose transfer function zeros are located on the unit circle, thereby causing some problems in performance. Specifically we study how the problems of blind channel equalization associated with the PR channels can be improved. In doing so, we first discuss the existing methods and then propose new structures for blind PR channel equalization. Our structures have been extensively tested by computer simulation and found out to be encouraging in performance. The results seem very promising as well in terms of the implementation complexity compared to the previous approach reported in literature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.570-575
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• 2019

Active muffler is implemented by applying active noise control technique to reduce exhaust noise of automobile muffler. Conventional Filtered_x LMS algorithm has a problem that the degree of control filter becomes very large and convergence deteriorates when acoustic feedback is present. The recursive LMS algorithm can compensate for this problem because it can be easily diverted in the adaptive filter adaptation process. In this paper, the structure of the primary path and the secondary path transfer function is designed as the IIR filter to improve the convergence performance and the computational burden, and the stabilization filter algorithm is applied to secure stability which is a disadvantage of the IIR filter structure. The stabilization filter algorithm plays a role of pulling the pole into the unit circle to prevent the pole of the transfer function corresponding to the acoustic feedback from diverging during the adaptation process. In this way, the computational burden of the active muffler system and the convergence performance can be improved. In order to show the usefulness of the proposed system, we compared the performance of the proposed Filtered_x LMS algorithm with the performance of the proposed system for the exhaust sound of a diesel engine, which is a variable environment. Compared to conventional algorithm, proposed algorithm's computational burden is less than half, and convergence performances are more than 4 times.

• Korean Journal of Heritage: History & Science
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• v.50 no.4
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• pp.168-197
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• 2017

This paper considers two aspects of the wooden chamber tombs with stone mound that were constructed in Wolseong North Burial Ground, in Gyeongju: tomb form and the group tomb complex. The basic unit of a wooden chamber tomb with stone mound consisted of a single round mound, covered with an additional earthen layer and surrounded by a circle of protective stones, within which a single wooden chamber was located. The form of a wooden chamber tomb with stone mound could therefore 1) be round, consisting of a single tomb unit, 2) consist of two or more attached tomb units, 3) or consist of multiple attached chambers in a single mound. The single tomb contained the burial of a single individual, and the attached tomb contained two or more individuals who were blood relations or connected by marriage. Multiple attached chambers tombs usually consisted of wooden chamber burials of the lowest rank, and have only been identified in the royal burial area of Wolseong North Burial Ground. At the Jjoksaem Area of Wolseong North Burial Ground, which is currently, under investigation, tombs have been found in small clusters along the slightly raised ground. This is likely the result of small groups of kin relations, upon selecting points along the slightly raised ground as their burial area, having constructed midsized and large single tombs and attached tombs along the axis of the slightly raised ground, which were then surrounded by smaller 'satellite' tombs. It is through this process that the tomb complex of the different groups came to be formed. The tombs of the royal burial area of Wolseong North Burial Ground, including the Daereungwon Tomb Complex, also formed group tomb complexes. Forming the centers of the group tomb complexes of the royal tomb area were huge individual round tombs where the Maripgan rulers were laid to rest or a gourd-shaped dual mound tomb, which was the final resting place of the king and his queen consort. These central tombs were surrounded by large and smaller tombs. Of the individuals that were buried in the group tomb complexes, there would have been individuals that were of equal status or social position, such as husbands and wives or blood relations, but it is unlikely that all of the buried individuals were related by blood, given the significant difference in the sizes of the tombs. It is likely that the individuals buried in the lower ranked tombs included in the group tomb complexes were 'dependents' of the deceased of the central tomb and his or her direct family who maintained a subservient relationship. Such tomb forms and group tomb complexes that can be observed amongst the wooden chamber tombs with stone mounds of Wolseong North Burial Ground provide insights into the nature of the social groups of the Silla center during the Maripgan Period. It is hoped that future studies undertaking a more detailed analysis of the data may make further contributions to unveiling the various aspects of Silla society.

• Journal of the Korean Geographical Society
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• v.30 no.1
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• pp.57-67
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• 1995

The study on the factorial ecology of the residential patterns is to provide one of the yardsticks for description and comparison of urban structures. Many Korean geographers have adopted this method to analyse the urban structure of Korean cities. According to these studies, one of the main factors in Korean cities in large and middle sizes is family status. The spatial pattern of family status is zonal, similar to the cases of Japanese and Western cities. The age is one of the principal indices of familyf status, hence the author chose the age composition to analyse the residential patten. This Paper is to describe the residential segreagation pattern due to age composition and recent pattern changes in the Cheongju city, and than to explain the reason for these changes. All data are derived from the Population Censuses of Korea for 1970, 1980 and 1990. Eighteen groups of age with five-year interval (0-4, 5-9, 10-14, 15-19, 20-24, 25-29, 30-34, 35-39, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-84, 85- and- over) are adopted here. Unit area for this analysis is administrative district(Dong) within Cheonaju city. District are classified into smaller groups based on the similarity of age composition, using the method of cluster analysis. The main findings are summarized as follows: 1. Population have increased remarkably in the eastern reaion neighboring CBD of Cheongju city in 1970's. And in western region from CBD new residential area have developed in 1980's. 2. Spatial pattarns showed a concentric circle type in central district and its neighbor regions and a sector type in periphery regions in 1970; a cirele type in central district and a sector typesin neighbor regions and periphery regions in 1980 and 1990. Thess residential pattern play an important role in the population composition ratio of younger aged group (l5-34) and older aged group (65-and-over). 3. Spatial change of types by age composition showed the higher ratio of groups of 0-9 and 35-49, and lower ratio of group 20-24 in 1970's. Dominent groups are ratio of 0-14, 40-49, 55-64, 7O-79, and 85- and- over in 1980's. These changes mainly appeared in central district and periphery regions. 4. The reasons for the change of age composition was the development of msnufacturing industries with the increase of population and new construction of residential areas both in the neighbor regions of cnetral district and periphery regions. These phenomena were caused by immigration of younger aged groups and increasing of residents of aged groups in these regions.

• Land and Housing Review
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• v.4 no.1
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• pp.77-87
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• 2013

About 1,800 villages have released from Greenbelt since Greenbelt-reform-policy for readjustment of the area was promoted after 1997. Even though the government intended to attract planned development & improvement of these lifted villages through District Unit Plan and designating the lifted area as low-rise and low-density zoning considering the characteristics of the Greenbelt region, there are still many problems to be solved: a lack of funds, insufficient capability for self-improvement and unexecuted SOCs in long-term etc. It seems that these problems are caused by focusing on the lifting areas itself instead of researching deeply the condition and characteristics of the villages and searching proper direction/plans of improvement before lifting Greenbelt In addition, the existing plan of village improvement and management was not considering physical and spacial characteristics of the areas, social and economic situation of residents and relationship between the villages and surrounding cities, though these conditions are different among each villages, and the related regulations are applied uniformly across all the villages and those have been causing many civil appeals and environmental problems. In these respects, this study aims to consider the problems of the lifted villages using the existing researches on them and to make typology by characteristics-data of the villages and to establish improvement strategies of each types. In this study, the villages were classified into 5 types as a result of cluster analysis on 424 villages among all 1,800 through variables of locational potentiality : location, accessibility, size and form of village, condition of regulations etc. According to function of the villages, they were divided into 4 types: urban-type, rural-type, industrial-type and neighborhood-centered-type. This study also drew 4 improvement-strategy-types by combination of locational potentiality and village-function : type of improving life-environment, type of improving production-infra, type of inducing-planned-improvement and type of constructing center-of living-circle. Finally, this study suggested the directions of the each 4 types to desirable improvement and management which could be used to make and complement plans for village improvement.

• Journal of Climate Change Research
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• v.3 no.2
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• pp.117-128
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• 2012

The Government of South Korea has continued its effort to fixate virtuous circle of economic growth and climate change response to cope with international demands and pressure to commitment for greenhouse gas reduction effectively. Nationally, Korean Government has established "Enforcement of the Framework Act on Low carbon, Green Growth"(2010. 4. 13) to implement national mid-term GHG mitigation goal(30% reduction by 2020 compare to BAU), which established the foundation for phased GHG mitigation by setting up the sectoral and industrial goal, adopting GHG and Energy Target Management System. Also, follow-up measures are taken such as planning and control of mid-term and short-term mitigation target by detailed analysis of potential mitigation of sector and industry, building up the infrastructure for periodic and systematic analysis of target management. Likewise, it is required to establish more accurate, reliable and detailed sectoral GHG inventory for successfully establishment and implement the frame act. In comparison to the $CO_2$ emission, Especially fluorinated greenhouse gases (HFCs, PFCs, $SF_6$) are lacking research to build the greenhouse gas inventories to identify emissions sources and collection of the applicable collection activities data. In this study, with the refrigeration and air conditioning sector being used to fluorine refrigerant(HFCs) as the center, greenhouse gas emission estimation methodology for evaluating the feasibility of using this methodology look over and mobile air conditioning, fixed air conditioning, household refrigeration equipment, commercial refrigeration equipment for the greenhouse gas emissions were calculated. First look at in terms of methodology, refrigeration and air conditioning sector GHG emissions in developing country-specific emission factors and activity data of the industrial sector the construction of the DB is not enough, it's 2006 IPCC Guidelines Tier 2a (emission factor approach) rather than the Tier 2b (mass balance approach) deems appropriate, and each detail by process, sectoral activity data more accurate, if DB is built Tier 2a (emission factor approach) can be applied will also be judged. Refrigeration and air conditioning sector in 2009 due to the use of refrigerant greenhouse gas emissions ($CO_2eq.$) assessment results, portable air conditioner 1,974,646 ton to year, fixed-mount air conditioner 1,011,754 ton to year, household refrigeration unit 4,396 ton to year, commercial refrigeration equipment 1,263 ton to year was estimated to total 2,992,037 tons.