• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2473-2479
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• 2013

The kinetics of the radical-polar molecule reaction $CH_3+HBr{\rightarrow}CH_4+Br$ has been studied at temperatures between 150 and 1000 K using classical dynamics procedures. Potential energy surfaces constructed using analytical forms of inter- and intramolecular interaction energies show a shallow well and barrier in the entrance channel, which affect the collision dynamics at low temperatures. Different collision models are used to distinguish the reaction occurring at low- and high-temperature regions. The reaction proceeds rapidly via a complex-mode mechanism below room temperature showing strong negative temperature dependence, where the effects of molecular attraction, H-atom tunneling and recrossing of collision complexes are found to be important. The temperature dependence of the rate constant between 400 and 1000 K is positive, the values increasing in accordance with the increase of the mean speed of collision. The rate constant varies from $7.6{\times}10^{-12}$ at 150 K to $3.7{\times}10^{-12}$ at 1000 K via a minimum value of $2.5{\times}10^{-12}\;cm^3\;molecule^{-1}\;s^{-1}$ at 400 K.

• Animal Systematics, Evolution and Diversity
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• 제36권4호
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• pp.347-353
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• 2020

Although sea slaters Ligia have a significant role in rocky shore habitats, their taxonomic entities have not been clearly understood. In this study, we investigated whether genetic variation inferred from a nuclear genetic marker, namely amplified fragment length polymorphism (AFLP), would conform to that of a mitochondrial DNA marker. Using both the mitochondrial DNA marker and the AFLP marker amplified by the six selective primer sets, we analyzed 95 Ligia individuals from eight locations from East Asia. The direct sequencing of mitochondrial 16S rRNA gene revealed three distinct genetic lineages, with 9.8-11.7 Kimura 2-parameter genetic distance. However, the results of AFLP genotyping analysis with 691 loci did not support those of mitochondrial DNA, and revealed an unexpectedly high proportion of shared polymorphisms among lineages. The inconsistency between the two different genetic markers may be explained by difference in DNA evolutionary history, for example inheritance patterns, effective population size, and mutation rate. The other factor is a possible genomic island of speciation, in that most of the genomic parts are shared among lineages, and only a few genomic regions have diverged.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2453-2458
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• 2010

Photochemical studies of N-[(trimethylsilyl)alkyl]saccharins were carried out to investigate their photochemical behavior. Depending on the nature of the substrate and the solvent system employed, reactions of these substances can take place by either SET-promoted silyl migration from carbon to either the amide carbonyl or sulfonyl oxygen or by a N-S homolysis route. The results of the current studies show that an azomethine ylide, arising from a SET-promoted silyl migration pathway, is generated in photoreactions of N-[(trimethylsilyl)methyl]saccharin and this intermediate reacts to give various photoproducts depending on the conditions employed. In addition, irradiation of N-[(trimethylsily)ethyl]saccharin produces an excited state that reacts through two pathways, the relative importance is governed by solvent polarity and protic nature. Finally, photoirradiation of N-[(trimethylsilyl)propyl]saccharin in a highly polar solvent system comprised of 35% aqueous MeOH gives rise to formation of a tricyclic pyrrolizidine and saccharin that generated via competitive SET-promoted silyl transfer and $\gamma$-hydrogen abstraction pathways.

• 한국토양비료학회지
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• 제48권3호
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• pp.180-188
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• 2015

To investigate the tendency of $Li^+$ exchange from polar organic solvents, $Li^+$-ion exchange into zeolite Y (Si/Al = 1.56) was attempted by undried methanol (crystal 1) and formamide (crystal 2) solvent. Two single crystals of Na-Y were treated with 0.1 M LiNO3 in each of the two solvents at 323 K, followed by vacuum dehydration at 723 K. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd{\bar{3}}m$, at 100(1) K. In both structures, $Li^+$ for $Na^+$ ions filled preferentially sites I' and II. The remaining $Na^+$ ions occupied sites I', II, and III' in both structures, in additional to above sites, and $Na^+$ ions occupied site I in crystal 2. While the 68 % exchange of $Li^+$ for $Na^+$ was achieved from undried methanol, only 40 % exchange was observed from undried formamide, indicating that the undried methanol was more effective than undried formamide as solvent for $Li^+$ exchange under the conditions employed.

• 자원환경지질
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• 제41권2호
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• pp.173-181
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• 2008

한반도 경기편마암 육괴내 서산층군과 시흥층군의 대표적인 변성암 시료에 대하여 CHIME 절대연령 측정을 실시하였다. 경기편마암복합체 변성암중의 모나자이트 CHIME연령은 234${\sim}$257 Ma로 페름기-트라이아스기 중기에 속하고 있다. 이 연령은 경기육괴내 흥성지역의 변성시기(231 Ma, Kim et al., 2006)와 오대산 지역의 변성시기(245${\sim}$248 Ma, Oh et al., 2006b)와도 조화적이며 남중국지괴와 북중국 지괴의 충돌에 의한 송림 변동으로 일어난 지각변동과 수반된 변성작용의 시대로 해석된다. 한반도의 경기육괴 서산층군과 시흥층군의 변성암의 변성연대는 다비-수루 충돌대의 변성 연대(220${\sim}$242 Ma, Yang et al., 2003; Liu et al., 2003, 2004) 보다 오래되며 이는 남중국과 북중국 지괴의 충돌이 중국대륙에서 보다 한반도 지역에서 선행되었을 가능성을 시사하고 있다.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1999년도 제13회 식물생명공학심포지움 New Approaches to Understand Gene Function in Plants and Application to Plant Biotechnology
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• pp.85-89
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• 1999

Somatic embryogendesis is one of good examples of the basic research for plant embryo development as well as an important technique for plant biotechnology. This paper describes the direct somatic embryogenesis from zygotic embryos of Panax ginseng is reversely related to normal axis growth of zygotic embryos by the experiment of various chemical treatments. Under the normal growth condition, the apical tips of embryo axis produced an agar-diffusible substance, which suppressed somatic embryo development from cotyledons. Although the cells of zygotic embryos were released from the restraint of embryo axis, various factors were still involved for somatic embryo development. Electron microscopic observation revealed that the ultrastructure of cells of cotyledon epidermis markedly changed before initiation of embryonic cell division, probably indicating reprogramming events into the cells embryogenically determined state. Polar accumulation of endogenous auxin or cell-cell isolation by plasmolysis pre-treatment is the strong inducer for the somatic embryo development. The cells for the process of somatic embryogenesis might be determined by the physiological conditions fo explants and medium compositions. Direct somatic embryos from cotyledons fo ginseng were originated eithrer from single or multiple cells. The different cellular origin of somatic embryos was originated either from single or multiple cell. The different cellular origin of somatic embryos was depended on various developmental stages of cotyledons. Immature meristematic cotyledons produced multiple cell-derived somatic embryos, which developed into multiple embryos. While fully mature cotyledons produced single cell-derived single embryos with independent state. Plasmolysis pretreatment of cotyledons strongly enhanced single cell-derived somatic embryogenesis. Single embryos were converted into normal plantlets with shoot and roots, while multiple embryos were converted into only multiple shoots. GA3 or a chilling treatment was prerequisite for germination and plant conversion. Low concentration of ammonium ion in medium was necessary for balanced growth of root and shoot of plantlets. Therefore, using above procedures, successful plant regeneration of ginseng was accomplished through direct single embryogenesis, which makes it possible to produce genetically transformed ginseng efficently.

• Ocean and Polar Research
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• 제38권1호
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• pp.21-33
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• 2016

Gametogenesis of the comb pen shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) on the southern coast of Ulleungdo Island, Korea was assessed monthly (November 2013 to October 2014) using histology. Gametogenesis commenced in January when the surface water temperature was $12.6^{\circ}C$ and pen shells evidenced an early development phase with small oogonia from January to April, although few females exhibited ripe eggs in their follicular epithelium. In April, the oocyte diameter increased rapidly, and fully mature eggs appeared in May. First spawning males and females were observed in June as the surface water temperature reached $19.3^{\circ}C$ and July ($23.2^{\circ}C$) respectively. The spawning activity continued until the end of September. Histology indicated that the spawning peak of the females in Ulleungdo Island was July to August. During October to January, most of the pen shells were in spent and resting stages. Our data suggested that A. pectinata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. The present study is the first provided fundamental information on the life history of A. pectinata in Ulleungdo Island, and this can be put to good use in the management of this pen shell in the study area.

• Ocean and Polar Research
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• 제42권1호
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• pp.77-88
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• 2020

This paper presents the coordinate systems used for trawl doors modeling, and provides matrix equations of connection between these systems. The projections of the forces acting on the door into axes of various coordinate systems were obtained, which were used in the door equilibrium equations. Six equilibrium conditions for the door as a solid were obtained: formulas that allow for the door area in plan to be determined; its weight in water; its mass; three moment equations for determining the position of the warp and backstrops fastening points to the door with triangular and quadrangular backstrop arrangements. It was found that the moment equilibrium equations of trawl doors are generally incompatible, which was not found by any of the authors who have previously conducted research into trawl doors. Using the Kronecker-Capelli theorem, the compatibility equation is obtained. This equation includes the coordinates of the backstrop fastening points to the door, which means that these points cannot be randomly selected. The technique of determining the warp and backstrops' fastening points position to the door is described. Conditions of directional (by angle of attack) and roll (in angle of roll) stability of the doors' equilibrium are presented. The equations presented in this paper comprise a mathematical model that allows, when designing the doors, to select optimal parameters, as well as to carry out adjustments for trawling purposes to ensure the stable movement of the doors and the entire trawl system.

• 한국지구과학회지
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• 제43권5호
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• pp.639-646
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• 2022

경상분지 신동층군의 백악기 진주층 일부 사암에서 산출되는 흑색의 불투명 탄화수소인 고열역청(pyrobitumen)의 산상을 처음으로 보고한다. 고열역청은 녹니석 공극벽 선충진(pore-lining) 교결물을 피복하거나 교결물 끝부분에 스며들어간 상태로 산출되므로, 녹니석 교결물 침전 이후에 생성된 것이며, 이는 과거 원유가 존재했음을 지시한다. 액상의 탄화수소는 진주층이 상당한 깊이로 매몰되는 동안 유입되었으며, 진주층 사암은 저류암의 역할을 했던 것으로 보인다. 진주층에 고열역청이 존재하는 것은 진주층이 액상 탄화수소의 이동 이후 심부 매몰과정을 겪었음을 지시한다. 그 후 매몰 온도가 더 증가하면서 탄화수소의 열분해가 일어나고 고열역청이 저류암에 잔류물로 남게 되었다.

• 한국동물학회지
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• 제20권3호
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• pp.141-147
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• 1977

한국 재래산양 50마리의 신정맥 vinylite를 주입하여 주형표본을 만들어 신정맥의 분포상태를 관찰하여 다음과 같은 결과를 얻었다. 1. 신장의 구역정맥들이 모여서 신정맥지를 이루고, 신정맥은 $2\\sim 3$개의 신정맥지로서 구성되나, 2개의 신정맥지인 경우가 많았다. 2. 신정맥은 전지(Ramus cranialis)와 후지(Ramus caudalis)로 구성되는 경우, 배지(Ramus dorsalis)와 복지(Ramus ventralis)로 구성되는 경우, 전지 $\\codt$ 중지(Ramus medius)후지로 구성되는 경우 그리고 $배지\\cdot 중지 \\cdot 복지$로 구성되는 경우가 있었는데, $배지\\cdot 복지$로 되는 경우가 가장 많았다. 3. 정맥성 구역은 $좌\\cdot 우신$, $배\\cdot 복면$이 각각 $2\\sim 4$개 였으며 3개인 경우가 가장 많았다. 4. 신장의 배면과 복면의 전단, 또는 후단 그리고 $전\\cdot 후양단$에서 공통구역을 형성하는 경우도 있었다. 5. 신극정맥의 출현은 없었다. 6. 신정맥의 주행과 분포상태는 신동맥과는 현저히 달랐다.