컴퓨터 시스템 保安에 關한 硏究

이희준 해군대학 1984 海洋戰略 Vol.- No.33

Experimental Assessment on the Internal Instability of Broadly Graded Silty Sand

이희준,김인현,정충기 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.4

Suffusion can occur when fine particles are under low effective stress and free to travel through constrictions between coarse particles, and sufficient seepage forces move the fine particles through the voids. Generally, gap-graded soils, which are a binary mixture of two distinct particle sizes, are susceptible to suffusion. Such soils show clear manifestations of suffusion, such as a significant quantity of fine particles discharged and an increase in permeability and void ratio. Therefore, in previous studies on seepage erosion problems, gap-graded soils were mostly utilized as the target soil. However, it is not clear whether the broadly graded soils, the fill dam materials in South Korea, are susceptible to suffusion according to the existing criteria and previous research. Additionally, experimental studies on broadly graded soils have rarely been conducted, especially in terms of hydraulic conditions. Therefore, a deeper understanding of the suffusion progress on broadly graded soils under various hydraulic conditions (hydraulic gradients) is required. In the present study, suffusion tests were performed on gap-graded andbroadly graded soils with different relative densities by using the newly developed suffusion test apparatus. During the test, the hydraulic gradient was increased stepwise, and the occurrence and progress of internal erosion were analyzed based on the amount of discharged soil and the coefficient of permeability. In contrast to gap-graded soils, the test results for broadly graded soils showed a continuous reduction in k before the initiation of erosion. At the onset of internal instability, sudden increases in k and soil discharge occurred under a relatively high hydraulic gradient. Additionally, a series of seepage tests on broadly graded soils showed that the higher the relative density, the higher the hydraulic gradient required to reach an unstable state.

Geological Consequences of the Saemangeum Dyke, Mid-West Coast of Korea: A Review

이희준,이수환 한국해양과학기술원 2012 Ocean science journal Vol.47 No.4

The Saemangeum Dyke is located in an estuarine setting, regulated in a complicated manner by a macrotidal regime, rivers, and winter monsoon. Accordingly, the constructed dyke resulted in a variety of artificial changes in geological characteristics in the estuary and its vicinity. To investigate those dyke-induced changes, the KORDI (Korea Ocean Research and Development Institute) performed sedimentological and sediment-dynamical observations from 2002 to 2010. On the basis of the KORDI results, the major geological changes and associated dynamical processes are reviewed. Five phenomena, among others, are focused on: depositional-channel creation; gap-related erosion; forced movements of surface sands; tidal-flat growth inside the dyke; and blanketing of mud over the sandy seafloor. These phenomena were unforeseen before the dyke construction, and reflect that the dyke could cause both erosion and deposition on an estuarine scale. The investigations conclude that the sediments in the dyke-influenced region were derived from the two rivers, Mangyeong and Dongjin, of the estuary. This is completely contrary to the offshore origin proposed before the dyke construction. As a result, the review supports the proposal that a thorough geological investigation and rational forecast is necessary prior to dyke construction to avoid economic loss and a fractious environmental debate.

4~5세기 신라 고분 피장자의 服飾品 着裝 定型

李熙濬 한국고고학회 2002 한국고고학보 Vol.47 No.-

This article aims to reconstruct the costume regulation system by analysing the patterns of association of dress accessories worn by the deceased at Silla tombs of the 4th and 5th centuries situated in the region east to the Naktong River. The costume accessories analysed are as follows: crown and cap, cap ornament, thick hollow earring, thin solid earring, necklace, sword, belt ornament, bracelet, finger ring. For Silla tombs at Kyungju area, twelve groups of association appear from the preliminary analysis. They are supposed to represent some kind of ranks, but they themselves do not necessarily correspond to the real discrete groups in the ruling class. The most important pattern of association is that each group includes either hick hollow earring or thin solid earring. These different kinds of earring is thought to have been worn by the opposite sexes, i.e., the former by the female, the latter by the male. So the whole groups first can be clustered into six and they can ultimately be regrouped into three according to the items they have besides earring. One group has the association of a kind of earring, belt ornament and necklace or sword. Another a kind of earring and a belt ornament. The other a kind of earring, a necklace, a sword and a belt ornament. These three groups of association are thought to have been the basic costume accessories of the three ranks in the central ruling class of Silla. Association patterns for tombs of local areas are basically same as those of Kyungju, but they tend to concentrate to the second group. These relatively low ranks that local chiefs got in dress accessories are attributed to the differential application of the costume regulation to them by the central ruling class, but they are complimented by cap ornaments which have the symbolic meaning of chiefs.

太王陵의 墓主는 누구인가?

李熙濬 한국고고학회 2006 한국고고학보 Vol.59 No.-

不実企業体整理에 대한 業界의 反省

李羲俊 한국마케팅연구원 1969 마케팅 Vol.3 No.5

DC 인버터 저항 스폿 용접에서 후전류 효과에 관한 연구

이희준,이세헌,Lee, Hui-Jun,Rhee, Se-Hun 한국생산제조학회 2009 한국생산제조학회지 Vol.25 No.2

Resistance spot welding has been investigated to apply for manufacturing car bodies because of its high productivity. So quality of resistance spot weld is one of the major concerns for both automobile and aerospace industry. Current design trends in automotive manufacture have shifted emphasis to alternative lightweight materials in order to aid in producing vehicles with higher fuel efficiency and lower down the vehicle emission level for environmental control. There is increasing emphasis to provide lighter cars. Therefore there is an effort to use high strength steels such as HSLA, dual phase, in car body. However there is used in restricted because of difficulty in producing consistently high quality resistance spot welds. In this study, resistance spot welding schedules were developed to achieve acceptable welds with improved static mechanical properties. Improved resistance spot welding schedules were developed using post heating current to reduce the cooling rate, or in-process tempering to reduce the hardness of the weld produced. The effects of resistance spot welding process parameter on hardening fracture mode and static mechanical properties of the joints were determined.

Preliminary Results on Suspended Sediment Transport by Tidal Currents in Gomso Bay, Korea

이희준 한국해양과학기술원 2010 Ocean science journal Vol.45 No.3

This study briefly investigated sediment transport by tidal currents in Gomso Bay, on the mid-west coast of Korea during the summer season. Hydrodynamic measurements with benthic tripods (TISDOSs) show that near-bed suspended sediments are transported toward the bay mouth along the lowwater line of tidal flats in the southern part of the bay, while they are directed offshore in front of the major tidal channel at the bay mouth according to tidal asymmetry. However, suspended sediments in the main body of sea water, observed from transect and anchor-site measurements, indicate a consistent incoming toward the uppermost tidal flats. A brief episode of relatively strong winds from the west and southeast displays that wind waves can yield the near-bed suspended sediment concentrations (SSC) overwhelming the SSC by tidal currents alone in the remaining duration.

A Review of Sediment Dynamical Processes in the West Coast of Korea, Eastern Yellow Sea

이희준 한국해양과학기술원 2014 Ocean science journal Vol.49 No.2

Sediment dynamical processes began to be systematically monitored in the west coast of Korea facing the eastern Yellow Sea in the 1990s. The early investigations were largely conducted aboard vessels that provided results where the resolution was highly restricted in both temporal and spatial aspects. However, full-fledged autonomous instruments introduced early in the 2000s allowed for a quantum leap in the level of this sub-field of sedimentology. The investigated sites include various environments such as estuaries, bays, tidal flats, beaches, and offshore deposits. Among them, a total of seven sites were selected for the review: Han estuary, Daeho tidal flats, Garolim Bay, Saemangeum Region, Byunsan Beach, Gomso Bay, and Huksan Mud Belt. The major results from each site were briefly summarized. The summary clearly demonstrates that wind-generated currents and waves particularly during winter should be carefully considered in interpreting sedimentary environments. This is because winter-season processes interrupt or actively displace much of the sediments worked by tidal currents in the remaining seasons. The summary hence suggests that seasonal investigations of sediment dynamics are necessary to understand shallow-water sedimentation in the west coast of Korea that is governed complicatedly by two major forcing agents: waves and tidal currents.

경주 황성동유적으로 본 서기전 1세기~서기 3세기 사로국

이희준 동국대학교 WISE(와이즈)캠퍼스 신라문화연구소 2011 新羅文化 Vol.38 No.-

'Saro' state seems to have been established around the turn of the 1st century B.C. as seen from the standpoint of the so-called local state hypothesis by having Hwangseongdong site as an axis of spatio-temporal comparison based on the distribution of coffin tombs sites in the Gyeongju basin. 'Saro' state is supposed to have been composed of six towns each of which were located in the present city center, the western district, the southern district, the northern district, and the southeastern district, the last being divided into two. The establishment of 'Saro' state must have been the end result of a somewhat long term social process triggered by various variables among of which the continuous immigration of peoples from northen region of the Korean peninsula and the production of iron were just the two important ones. The chieftains of the emergent state, towns and settlements who were the rulers from several ruling lineages seems to have secured the ideological and economic power, but not the military power in the light of an analysis of the characteristics of their grave goods. But the chieftains of the 1st century A.D. are thought to have begun to accumulate the military power as seen from the exceptionally extravagant grave goods of Sarari coffin tomb no. 130 including lots of iron arrowhead but the status and power of the ruler interred in that tomb seems not yet to have been succeeded to other members of the same lineage, hence the office of rulership not fixed in one town. The situation changed rapidly with the emergence of wooden chamber tombs which are evaluated as reflecting the restructuring of existent order when the rulers fully secured the military power as evidenced by the magnitude of iron weapons interred into their tombs. The new wooden chamber tombs were located apart from the existing coffin tombs and among these several are prominent unlike the latter, which can be interpreted as the result of the formation of several competing ruling lineages. The primary town should have been located in the present Gyeongju city center by no later than this time. Hwangseongdong iron working complex must have contributed much to the economic development of the town and the state as well.