• The Korean Journal of Quaternary Research
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• v.16 no.2
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• pp.33-38
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• 2002

28 direction of the past Korean geomagnetic field were determined by archaeomagnetic measurements of 734 oriented samples, collected from baked earths of remains in the southern Korea. These data cover periods of A.D. 39C, A.D. 1317 and A.D. 15-l6C. It is noted that Korean geomagnetic field data in 5-6C arc similar to those of contemporary Japanese geomagnetic field, but Korean geomagnetic field data in A.D. 3-4C deflect more easterly than contemporary Japanese geomagnetic field. The observed large difference of geomagnetic field direction between Korea and Japan suggests the existence of a prominent local geomagnetic anomaly in the vicinity of Japan and Korea in the period of A.D. 3-4C. An approximate figure of Korean archaeomagnetic secular curve for the periods of A.D. 3-6C and A.D. 7-9C was obtained. This curve is sure to be helpful for Korean archaeology to data the last firing of baked earths accompanied with no relics.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.466-477
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• 1994

PEG 600-diglycidyl ethers(PDE) were synthesized using $BF_3$ catalyst by the reaction of epichlorohydrin and PEG 600 which is known to have the hygroscopicity, softening property, and antistatic property. Water-soluble long chain polyamines(PDET) were synthesized by coreaction of PDE and triethylenetetramine which is high conductive aliphatic amine curing agent. To prevent the gelation of the PDET and increase the water-solution stability, water-soluble quaternary ammonium polyamines were synthesized by cationation of PDET with acetic acid. Antistatic agents PDET-2A, PDET-5A, PDET-6A, PDETA-2A and PDETA-4A were prepared by the mixing of PDET-2, PDET-5, PDET-6, PDETA-2 and PDETA-4 with water. Synthesized antistatic agents were treated on PET textiles with and without resin. Then surface electrical resistivity and half life characteristics value were tested. As the results there were no remarkable decreasing changes in antistatic abilities of the textiles treated with PDETA-2A and PDETA-4A after 50 times washing. So PDETA-2A and PDETA-4A were proved to be durable antistatic agents. Surface electrical resistivity of the textiles treated with PDETA-2A and PDETA-4A before washing were $1{\times}10^7{\Omega}$ and $2{\times}10^7{\Omega}$, respectively, and half life characteristics values were 0.8sec and 1.1sec, respectively. Therefore PDETA-2A and PDETA-4A were proved to be good antistatic agents.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.457-463
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• 2003

A general program of meanline design and/or performance prediction for centrifugal/mixed-flow compressors is successfully commercialized using various empirical loss models. 4 types of diffusers, 3 types of exit elements, shrouded/unshrouded impellers and real gas option are included in the program capabilities. Total 16 cases of benchmark test results proved its reliability to be effectively utilized in the development processes.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.443-458
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• 2005

Late Quaternary deposits of the core in the western area of the Nakdong River delta consist of four sedimentary units: Unit I, II, III and IV, in ascending order, controlled by the sea-level change since the last interglacial period. Unit I unconformable overlying Cretaceous basement rocks is composed of sandy gravel and sand deposited in a fluvial channel before the first marine transgression. Unit II composed of stiff massive mud is interpreted as a shallow marine deposits formed during the last interglacial period (probably MIS 5). The development of the fissures coated with oxidized materials in the upper part of Unit II is a feature of subaerial exposure, which indicates erosional contact with the upper Unit III. Unit III is made up of soft massive mud and soft shelly massive mud deposited in a tidal flat and a inner shelf, respectively, since the Holocene transgression (about 9,000 yr BP). Unit Ⅳ consisted of soft shell bedded mud and yellowish sandy mud was deposited in the delta environments during the regression (after about 5,000 yr BP). The lower shell bedded mud was deposited in a tidal flat and the upper sandy mud was deposited in the floodplain corresponding to present site of the Nakdong River delta.

• Journal of the Korean earth science society
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• v.25 no.5
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• pp.377-377
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• 2004

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.3
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• pp.410-418
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• 1994

다양한 유기관능기를 가진 Silane가요제의 기능 양면성과 독특한 화학적 구조는 이들이 면섬유의 물성을 향상시키기 위한 in-situ 중합 및 가교처리의 단량체로 사용될 수 있는 가능성을 시사하므로, 본 연구에서는 이를 위한 기초 실험으로 수용액 상의 silane 단량체의 거동과 in-situ중합의 가능성을 조사하였다. 관능기를 달리하는 methyltriethoxysilane (MES), vinyltriethoxysilane (VES), vinyltriacetoxysilane (VAS)과 epoxy (glycidoxy) propyltrimethoxysilane (EMS) 등이 silane단량체로 선택되었다. Silane수용액의 안정성과 용해도는 단량체의 농도가 증가함에 따라 감소하였으며, pH에 의해서도 크게 영향을 받아 PH 3과 4.5사이에서 가장 안정함을 나타내었다. 10분간의 중기 고착과정에 의해서 충분한 양의 단량체가 면섬유 안으로 확산되었으며, 섬유의 방추성은 반응성이 높은 organotin촉매제를 사용하여 열처리한 후 증가되었다.

• Applied Chemistry for Engineering
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• v.35 no.2
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• pp.128-133
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• 2024

Although antisolvent-assisted crystallization is one of the promising processes to produce high-quality perovskite films, general antisolvents such as chlorobenzene (CB) have toxic and volatile properties. In addition, CB is not suitable to control the crystallization of perovskite in the atmospheric air. In this work, isopropyl acetate (IA) is used as an eco-friendly antisolvent to demonstrate air-processed perovskite solar cells, and ethyl-4-cyanocinnamate (E4CN) with a cyano group, carbonyl group, and aromatic ring is introduced in IA to improve the performance and stability of devices. Defects at the surface and grain boundaries of the perovskite layer, such as un-coordinated Pb²⁺ and iodine, can be decreased resulting from the interaction of E4CN and perovskite, and thus reduced recombination and enhanced carrier transport can be expected. As a result, the perovskite device with E4CN achieves a high maximum power conversion efficiency (PCE) of 18.89% and outstanding stability, maintaining 60% of the initial efficiency for 300 h in the air without any encapsulation.

• The Korean Journal of Quaternary Research
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• v.15 no.2
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• pp.101-109
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• 2001

The landscape changes at the Mujechi moors I and II during the last twenty two years were analysed using a tree ring analysis of pine trees, a distributional pattern of pine tree, an aerial photograph interpretation and a measurement of firebreak line. The analysis of aerial photographs(taken in 1978, 1988, 1998) indicates that the area of Mujechi moors I and II have gradually decreased. The decreased rate of moor area was relatively high, i.e.,-23.9 %(1978~1988) and -16.4 %(1998~1998) at the Mujechi moor I, but a little bit low, i.e., -2.6% (1978~1988) and -12.6 % (1998~1998) at the Mujechi moor II. However, dendrochronological analysis of pine trees at moors I and II shows that the appearance rates of pine trees per $100\textrm{m}^2$ at moor I and II were 0.28 and 0.57 respectively. And the number of younger pine trees(height is under 1.5m, DBH is less than 2.5 cm) invaded into moors are numbered eleven at the moor I, and ten at the moor II. This shows that the shift of a wetlands into a land was faster at the moor II than the moor I. The construction of a firebreak line and waterway along the moors I and II areas since the December, 1995, has diverted watershed flow and prohibited the runoff flow into the moors. The analysis of GIS suggests that the decreased watershed area were about $11,413.8\textrm{m}^2$(12.1 % of whole watershed area) at the moor I and $15,969.5\textrm{m}^2$(40.4 % of whole watershed area) at the moor II. The negative impact of firebreak line on the inflow of water into the moors I and II and destruction of vegetation along the firebreak line are noticeable from the field survey.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.139-144
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• 2003

The purpose of this study is to identify the species and to date the woods used in the Keunjung-jeon Hall, main building of the Kyungbok palace in Seoul. Samples (144) were divided into two parts, pillars (52) and other wood materials (92). Only two species were identified. They were Abies holophylla Max. and Pinus densiflora Sieb. et Zucc.Eleven among 20 Pyungju (outer pillars) were Abies holophylla, and 9 were Pinus densiflora. Seven among 12 Naejinkoju (inner pillars) were Abies holophylla, and 5 were Pinus densiflora. Three among 4 Gwikoju (inner corner pillars) were Abies holophylla, and one was Pinus densiflora. In the other wood materials, only 2 of 92 were Abies holophylla, and the others were Pinus densiflora. Tree-ring dating proved that this building was reconstructed during late 1860s. It also revealed that the old woods cut in the 17th century were reused.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.13-14
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• 2003

It is generally well known that Quaternary is characteristic geologically in terms of glacial and interglacial repeats and their associated unconformity formation. This paper deals with the first finding of the characteristic and significant meaningful unconformity between Holocene and late Pleistocene, which implies submergence and emergence of the tidal sedimentary basin along the western coastal zone of Korea during interglacial stage(IOS-5e) and glacial time(IOS-2). The stratigraphy of intertidal deposits in the Haenam Bay, western coast of Korea shows two depositional sequence units (Unit I of Holocene and Unit II of late Pleistocene) bounded by an erosional surface of disconformity. The disconformity is related to the latest Pleistocene sea-level lowstands (probably during the LGM). The Unit II is interpreted as intertidal deposit showing tidal sedimentary structures and crab burrow ichnology and has two parts (the upper part and the lower part) showing different lithology and character. The upper part of Unit II shows characteristic subaerial exposure features (emergence) and its related lithology. Such subaerially exposed upper part (more or less 4m to 5m in thickness) is characterized by yellow-brownish sediment color, cryoturbat-ed structure, crab burrow ichnofacies and high value of shear strength. Geochemical and clay mineral analyses of the upper part sediments also indicate subaerial exposure and weathering. In particular, very high value of magnetic susceptibility of the upper part in comparison to that of the lower part is interpreted as pedogenetic weathering during the subaerial exposure period.