• Economic and Environmental Geology
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• v.52 no.5
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• pp.409-425
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• 2019

Marine terraces, a step-like landform, are important geologic markers that provide tectonic information during the Quaternary Period. Marine terraces are well developed along all coastlines(East, West, and South) of the Korean Peninsula, those along the East coastline are the most distinctive. The marine terraces of the East coastline are classified into 4-6 flights that are several meters or several tens of meters above the present sea level. It is believed that these terraces, except for the lowest one, were formed in the middle Pleistocene. In the base of the OSL age dating results and Blake excursion events of magnetostratigraphy, the $2^{nd}$ and $3^{rd}$ terraces are correlated to the last interglacial stage. Considering the marine terraces linked to a sea-level curve of the Pleistocene, it is thought that regional tectonic movements have uplifted the East coastal area since the middle Pleistocene. Besides, former shorelines of each terrace have varied elevations from Gangreung to Busan bay, which can be divided into four regions, namely, Gangreung-Yonghanri(I), Homikot-Najung(II), Najung-Bangeojin(III), and Waesung-Busan Bay(IV). The former shorelines of each terrace at both Gangreung-Yonghanri(I) and Najung-Bangeojin(III) are higher than those in the other two regions, due to block movements by regional faults such as the Ocheon Fault or its subsidiaries, the Gampo Lineament and Ulsan Fault. Uplift rate of the East coast ranges from 0.2 m/ky to 0.3 m/ky, but each region shows different uplift rate.

• The Journal of the Petrological Society of Korea
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• v.25 no.3
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• pp.231-240
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• 2016

Three Quaternary faults have been revealed in marine terraces nearby the Homigot and the Gurongpo in the southeastern offshore of Korean Peninsula. The Hajung fault cuts the $4^{th}$ marine terraces and the Guman fault the $2^{nd}$, respectively. The Hajung fault strikes $N55^{\circ}$ to $45^{\circ}W$ and dips $40^{\circ}$ to $45^{\circ}NE$ with reverse-displacement of 180cm vertically. There are four sets of colluvial sediment strata that would be produced by faulting and indicate four times of fault movements during MIS 7 and MIS 5c. The Guman fault site consists of three sets of reverse faults that strike $N80^{\circ}E$ to $N70^{\circ}W$ and dip $25^{\circ}{\sim}35^{\circ}SE$ to $30^{\circ}SW$ with vertical displacement of 9~18 cm. The Guman faulting occurred during 80 ka (MIS 5a) to 71 ka (MIS 4) but it extends only to the lowest bed, the pebble sand bed, lay just on the unconformity, and not to the upper. Considering the attitude of the faults, we inferred that the Hajung fault was activated under the ENE-WSW compression during MIS 7 to MIS 5c and the Guman under N-S trending compression during MIS 5a. Using the OSL age dating results, we reconfirmed that the $2^{nd}$ terrace is correlated to MIS 5a and the $4^{th}$ terraces to MIS 7.

• The Korean Journal of Quaternary Research
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• v.7 no.1
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• pp.1-26
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• 1993

The estimation of the Last Interglacial sea level was made by using the thalassostatic terrace which had been developed in the lower reach of Namdaechon river in Kangneung, eastern coastal area of Korea. The fluvial terraces, which have been developed since late Pleistocene, were investigated. The main findings were as follows; 1) That Kangneung terrace I had been formed in the climax period of the Last Interglacial (Oxygen isotope stage 5e) was revealed. It was estimated that Kangneung terrace II had been formed during a certain warmer period between the climax period of the Last Interglacial and the early Last Glacial(probably Oxygen isotope stage 5c or 5a). 2) Being judged from the relative heights of the Kangneung terrace I and II, the sea levels of the formation periods of these terraces were estimated to have been relatively 17~20m and l0m higher than the present sea level, respectively. 3) The formation periods of the Wangsan terrace I and II were supposed to be the early and late Last Glacial respectively, being judged from the following 3 details ; a) the characteristics of the terrace deposits, b) the relation Wangsan terrace II to the buried valley floor, and c) the cross phenomena of the above two terraces to the Kangneung terraces. 4) The formation period of the pseudogleyed red soil in the Kangneung terrace I was estimated to be the middle or late period of the Last Interglacial.

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.271-273
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• 2002

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.447-462
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• 2009

Kohyun River basin is located at southern parts of Taebaek Mountains and most of river basins consists of sedimentary rock. The aims of this study are to investigate the distribution characteristics and processes of fluvial terraces at Kohyun River, using scientific methods such as classification of fluvial landforms, analysis of geomorphological deposits, XRD and OSL age dating. In Kohyun River basin are three levels terraces from T1 to T3. Fluvial terraces are assumed to be erosional terraces according to deposited situation of alurium and existences of bedrock riverbed. From the result of OSL age dating, formation age of fluvial terrace 1(T1) is calculated about 37,000 yr.B.P.(MIS 3), and fluvial terrace 2(T2) is calculated about 113,000 yr.B.P.(MIS 5). Therefore, fluvial terraces at Kohyun River are assumed to be formed at warmer period in the glacial stages or cooler period in the interglacial stages. The incision rate of fluvial terrace 1 at Kohyun River is calculated to be 0.054m/ka, and the incision rate of fluvial terrace 2 is calculated to be 0.115m/ka. This results suggest to lower incision rate than other rivers in Korea because of low uplift rates and little discharge.

• Journal of the Korean Geographical Society
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• v.35 no.2
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• pp.189-205
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• 2000

북한강 지류 홍천강은 중류구간과 하류구간의 하천 형태가 대조적이다. 홍천강의 중류는 단층선을 따라 직선상으로 남서류하고, 하류는 감입곡류 구간으로 서류하여 북한강에 합류한다. 유역분지의 기반암은 중류구간의 서쪽과 하류구간은 편마암, 중류구간의 동쪽은 화강암이며, 상류구간은 변성암과 화강암이 혼재한다. 하안단구는 중류구간 유로의 양안에서 넓게 분포하며, 하류구간에서는 감입곡류의 활주사면에 좁게 나타난다. 이러한 특징은 지질구조선의 존재, 중류와 하류의 지질 특성과 이에 따른 유로 발달의 차이에 기인한다. 화계분지는 중류구간의 가장 하류쪽에 위치하는데, 분지 내에는 고도를 달리하는 여러 단의 하안단구가 분포한다. 즉, 화계분지에서는 과거 여러 번에 걸친 유로변경과 이로 인해 곡류절단이 이루어졌다. 이는 변성암으로 이루어진 홍천강 하류의 좁고 깊은 하곡이 국지적인 침식기준면으로 작용하여 중류에서 하류로의 곡류대 이동이 방해받았기 때문이다. 하안단구의 형성시기는 기존의 연구결과와 비교할 때, 저위 I면과 저위II면이 각각 Early Wurm 빙기와 Late Wurm에 대비되는 marine oxygen isotope stage 4와 2 시기에, 중위면은 Late Riss에 해당하는 marine oxygen isotope stage 6에 형성된 것으로 추정된다.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.1-17
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• 2014

This study estimates geomorphological processes of fluvial terraces by uplifts and bedrock features, by the analyses of topography, distribution, formation age and incision rate of fluvial terraces using Gwang-cheon River in Uljin, Namdae-cheon River in Pyeonghae and Osip-cheon River in Yeongdeok located in the southern Taebaek Mountain Range. The tectonic and climatic terraces I in the upper reaches of Gwang-cheon River with an altitude from riverbed of 9~12m indicate the formation age of MIS 2 with a incision rate of 0.40m/ka. However, the tectonic and climatic terraces I in the upper reaches of Osip-cheon River with an altitude from riverbed of 7~10m show the formation age of MIS 3 with an incision rate of 0.10m/ka. These results suggest that the uplift rate in the Gwang-cheon River basin is likely to be higher than that in the Osip-cheon River basin. Unlike the lower reaches of Osip-cheon River, the thalassostatic terraces are not found in the lower reaches of Gwang-cheon River, because the basin has low maintainable ability of landforms in river valley due to high uplift rate and bedrock properties resistant to weathering and erosion. On the other hand, the lowest tectonic and climatic terraces in the study areas indicate different formative ages and the terraces during the cooling stage in interglacial as well as during interstadial are also found. Therefore, this study suggests that chronological method for fluvial terrace by the previous developmental model of climatic terrace should be reconsidered.

• Journal of the Korean Geographical Society
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• v.39 no.3
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• pp.425-443
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• 2004

Fluvial terraces is poorly developed along Bukhan River in Central Korea. Altitude from riverbed of T1 terraces are 18-29m, T2 terraces 2539m, respectively. Rubification index of T2 is 0.66, T1 is 0.54, and thickness of gravel weathering rind on gneiss of T2 are 14.0mm, granites of T2 are $\infty$, gneiss of T1 are 5.0mm and granites of T2 are 8.0mm, because weathering in deposits of T2 terraces, older than T1, is severer than T1 terraces. Since deposits in T2 have more active and longer weathering than T1, SiO$_2$/Al$_2$O$_3$ is 3.32 in T2 and 4.06 in T1, and SiO$_2$/R$_2$O$_3$ is 2.64 in T2 and 3.19 in T1. CIA(Chemical Index of Alteration) is 87.85％ in T2 and 85.88％ in T1. Kaolinite and halloysite are founded in deposits of T2 indicating high weathering, and are founded gibbsite made tv eluviation of kaolinite. However, deposits of T1 have no kaolinite, and are found plagioclase, weak mineral in weathering process. Comparing to previous researches by estimated age as altitude from riverbed, rubification index, thickness of gravel weathering rind, element contents and mineral composition, forming age of T2 terraces in Bukhan River are estimated in marine oxygen isotope stage 6 (130-190ka), and T1 terraces are marine oxygen isotope stage 4(59-74ka).

• Proceedings of the Korean Quaternary Association Conference
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• 2005.10a
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• pp.48-54
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• 2005

Terrace morphology is so conspicuous in the south eastern coastal areas. Coastal terraces can be divided into 5 main surfaces, including beach and coastal alluvial plain(AP, $4{\sim}5m$), Low Terrace(LT, 8 $^{\sim}$ 25m), Middle Terrace(MT, 36 $^{\sim}$ 55m), High Terrace(HT, 63 $^{\sim}$ 86m) and upper High Terrace(uHT, above 90m). Among them Lower Terrace Formation is distributed between 8m and 20m in altitude. Both Tephra deposited of LT2 formation and OSL datings of sand layers in LT 2 and LT 3 Formations support the age of the LT 2 formation is MIS 5d or 5e, most probably 5e. The age of LT 3 is interpreted MIS 5a, based on tephra production in organic mud layers and OSL dating of sand deposits just above the beach pebbles of the LT 3. Particularly the transgression, possibly equivalent to the well-known Monastirrian episode in the Mediterranean Sea.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1570-1576
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• 2000

하드디스크의 고용량화 추세에 따라 헤드의 정밀한 위치제어를 위한 큰 대역폭의 트랙추적 서보 시스템의 필요성이 대두되고 있다. 이에 작은 신호의 마찰을 제거하고 대역폭을 높이는 방법 중 하나인 2단구동기 트랙추적제어를 실시하여 큰 대역폭의 트랙 추적 서보시스템을 구성하는 방법에 대해 연구하였다. 2단구동기는 조동구동기(기존 하드디스크의 VCM)와 전단형 압전체를 부착한 미동구동기로 구성하였다. 미동구동기의 Hinge구조는 트랙 방향의 공진 주파수와 출력변위를 만족시키기 위한 구조로 설계하였다. 제어기는 notch filter와 PI 보상기를 사용하는 조동구동기와 notch filter와 PD 보상기를 사용하는 미동구동기를 다양한 구조로 구성한 것들을 비교하였다. 2단구동기는 VCM만을 사용하여 트랙 추적을 할 때보다 트랙 편심을 잘 추적하며, 기계적 공진과 VCM의 비선형성에 의해 제한된 대역폭을 개선시키는 효율적인 방법임을 확인하였다.