• 한국환경복원기술학회지
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• 제15권2호
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• pp.149-162
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• 2012

Habitat loss and fragmentation are ongoing major anthropogenic impacts on landscapes, which can strongly affect ecosystems, populations and species. The studies on forest fragmentation have been progressed, but the studies on definition of forest fragmentation and their synthetic trend in South Korea still leaves much to be desired. Therefore we set the definition of forest fragmentation and reviewed the related papers. We can give a definition that forest fragmentation is not only a process of spatial landscape transformation, but also a process of ecosystem change by it. The trend of studies on forest fragmentation divided into two fields, landscape and ecosystem changes. Forest fragmentation caused by land change altered the composition and configuration of forest patches. Most studies related on that analyzed the change using landscape index. The effects of forest fragmentation on ecosystem subdivided into three fields : biodiversity, edge effects, and invasive species, but the studies in South Korea is short. The study on relations between forest fragmentation and ecosystem change is necessary to face the Convention on Biological Diversity in South Korea. In addition, the fundamental studies on biodiversity is important to mitigate against forest fragmentation.

• Geomechanics and Engineering
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• 제16권2호
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• pp.195-204
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• 2018

Based on theories of rock mechanics, rock fragmentation, mechanics of elasto-plasticity, and energy dissipation etc., a method is presented for evaluating the rock fragmentation efficiency by using plastic energy dissipation ratio as an index. Using the presented method, the fragmentation efficiency of rocks with different strengths (corresponding to soft, intermediately hard and hard ones) under indentation is analyzed and compared. The theoretical and numerical simulation analyses are then combined with experimental results to systematically reveal the fragmentation mechanism of rocks under indentation of indenter. The results indicate that the fragmentation efficiency of rocks is higher when the plastic energy dissipation ratio is lower, and hence the drilling efficiency is higher. For the rocks with higher hardness and brittleness, the plastic energy dissipation ratio of the rocks at crush is lower. For rocks with lower hardness and brittleness (such as sandstone), most of the work done by the indenter to the rocks is transferred to the elastic and plastic energy of the rocks. However, most of such work is transferred to the elastic energy when the hardness and the brittleness of the rocks are higher. The plastic deformation is small and little energy is dissipated for brittle crush, and the elastic energy is mainly transferred to the kinetic energy of the rock fragment. The plastic energy ratio is proved to produce more accurate assessment on the fragmentation efficiency of rocks, and the presented method can provide a theoretical basis for the optimization of drill bit and selection of well drilling as well as for the selection of the rock fragmentation ways.

• 정보처리학회논문지A
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• 제8A권4호
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• pp.331-338
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• 2001

네트워크가 보편화되면서 사이버 공간을 이용한 테러가 전 세계적으로 발생하고 있다. IP Fragmentation은 이 기종 네트워크 환경에서 IP 패킷의 효율적인 전송을 보장해주고 있지만, 몇 가지 보안 문제점을 가지고 있다. 불법 침입자는 이러한 IP Fragmentation의 취약점을 이용해 IP Spoofing, Ping of Death, ICMP 등의 공격 기술을 이용하여 시스템에 불법적으로 침입하거나 시스템의 정상적인 동작을 방해한다. 최근에는 IP Fragmentation을 이용한 서비스 거부공격 외에도 이를 이용하여 패킷 필터링 장비나 네트워크 기반의 침입탐지시스템을 우회할 수 있는 문제점이 대두되고 있다. 본 논문에서는 패킷 재 조합 기능을 제공하지 못하는 일부 라우터나 네트워크 기반의 침입탐지시스템들에서 불법 사용자가 패킷을 다수의 데이터 그램으로 나누어 공격할 때, 이를 탐지하거나 차단하지 못하는 경우에 대비하여 실시간 접근 로그 파일을 생성하고, 시스템 관리자가 의사결정을 할 수 있도록 함과 동시에 시스템 스스로 대처할 수 있는 시스템을 구현하여 타당성을 검증하고, 그에 따른 기대효과를 제시하고자 한다.

• 디지털산업정보학회논문지
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• 제16권2호
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• pp.11-25
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• 2020

This study proposes a method to manipulate fragmentation of disks by arbitrarily allocating and releasing the status of a disk cluster in the NTFS file system. This method allows experiments to be performed in several studies related to fragmentation problems on disk cluster. Typical applicable research examples include testing the performance of disk defragmentation tools according to the state of fragmentation, establishing an experimental environment for fragmented file carving methods for digital forensics, setting up cluster fragmentation for testing the robustness of data hiding methods within directory indexes, and testing the file system's disk allocation methods according to the various version of Windows. This method suggests how a single file occupies a cluster and presents an algorithm with a flowchart. It raises three tricky problems to solve the method, and we propose solutions to the problems. Experiments for allocating the disk cluster to be fragmented to the maximum extent possible, it then performs a disk defragmentation experiment to prove the proposed method is effective.

• 한국지리정보학회지
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• 제2권3호
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• pp.16-22
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• 1999

생물서식지의 다양한 공간구조는 생물의 종 다양성과 밀접한 관계를 가지고 있다. 인구의 증가, 농업의 발달, 그리고 도시의 발전은 최근에 다양한 경관의 변화를 가져왔다. 이러한 경관의 변화는 생태적 구성인자의 서식지 감소와 파편화(fragmentation)를 초래하였다. 본 연구에서는 Landsat TM을 이용하여 식생지수를 산출하고 이를 식생 패치의 경계길이 대 면적 (perimeter : area, P/A ratio), Shape Index(SI), 프렉탈 디멘죤(D)에 의해 추출한 파편화지수를 분석하였다. NDVI에 의한 경관파편화의 분석은 0.5~1의 구간 값을 이용하는 것이 가장 파편화를 용이하게 구분할 수 있음을 알 수 있었다. 또한, 서울 경기지역의 식생 파편화는 프렉탈 디멘죤에 의해 구분할 때 가장 효과적으로 식생 패치의 파편화를 구분해 낼 수 있음을 알 수 있었다. 향후 동일지역에 대한 식생 패치의 시계열적인 분석과 다양한 토지이용에 대한 식생 파편화의 분석을 비교 연구하여 식생 보전과 생물다양성의 전략을 제시할 수 있을 것이다.

• Clinical and Experimental Reproductive Medicine
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• 제46권4호
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• pp.147-151
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• 2019

Objective: The aim of this study was to investigate DNA fragmentation status in human spermatozoa according to specific tail swelling patterns determined via hypo-osmotic swelling test (HOST). Methods: Frozen semen samples from 21 healthy donors were thawed and prepared by the swim-up technique for use in intracytoplasmic sperm injection. The semen samples were treated for 5 minutes as part of the HOST procedure and then underwent the sperm chromatin dispersion test using a Halosperm kit. DNA fragmentation status (large halo, medium halo, small halo, no halo, or degraded) and the specific tail swelling pattern ("a"-"g") were assessed at the level of a single spermatozoon. A total of 42,000 spermatozoa were analyzed, and the percentage of spermatozoa without DNA fragmentation (as evidenced by a large or medium halo) was assessed according to the specific tail swelling patterns observed. Results: The HOST examinations showed that > 93% of spermatozoa across all types displayed no DNA fragmentation. The percentage of spermatozoa without DNA fragmentation was 100% in type "d", 98.67% in type "g", and 98.17% in type "f" spermatozoa. Conclusion: We found that the type "d" spermatozoa displayed no DNA fragmentation, but the other types of spermatozoa also displayed very low rates of DNA fragmentation. This result may be associated with the processing of the spermatozoa by density gradient centrifugation and the swim-up technique.

• 미생물학회지
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• 제35권1호
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• pp.28-34
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• 1999

본 연구에서는 Yeast Artificial Chromosome을 효율적으로 조작하고 유유전자의 기능을 보다 더 용이하게 분석하기 위해 EMCV 바이러스의 IRES 염기서열과 $\beta$-galactosidase를 포함하는 새로운 bicistronic fragmentation vector를 제조하였다. 이 벡터의 폴리클로닝 site에 네 개의희귀한 제한효소 부위를 도입하여 DNA를 용이하게 클로닝할 수 있게 만들었다. 그러므로 원하는 어떤 YAC도 효모세포에서 쉽게 상동 재조함에 의해 절편할 수 있는 장점이 있다. 이 bicistronic fragmentation vector 시스템을 이용하면하나의 메시지로부터 연구하고자 하는 유전자와 $\beta$-galactosidase를 동시에 한 세포에서 발현할 수 있기 때문에 유전자의 발현양상을 쉽게 분석할 수 있는 새로운 도구로 이용할 수 있다.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2774-2780
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• 2014

A dynamics study of relaxation and fragmentation of icosahedral argon cluster with a vibrationally excited $Ar_2^+$ (${\nu}$) is presented. Local translation is shown to be responsible for inducing energy flow from the embedded ion to host atoms and fragmentation of the cluster consisting of various low frequency modes. The total potential energy of $(Ar_2^+)Ar_{12}$ is formulated using a building-up procedure of host-guest and host-host interactions. The time dependence of ion-to-host energy transfer is found to be tri-exponential, with the short-time process of ~100 ps contributing most to the overall relaxation process. Relaxation timescales are weakly dependent on both temperature (50-300 K) and initial vibrational excitation (${\nu}$ = 1-4). Nearly 27% of host atoms in the cluster with $Ar_2^+$ (${\nu}$ = 1) fragment immediately after energy flow, the extent increasing to ~43% for ${\nu}$ = 4. The distribution of fragmentation products of $(Ar_2^+)Ar_{12}{\rightarrow}(Ar_2^+)Ar_n+(12-n)Ar$ are peaked around $(Ar_2^+)Ar_8$. The distribution of dissociation times reveals fragmentation from one hemisphere dominates that from the other. This effect is attributed to the initial fragmentation causing a sequential perturbation of adjacent atoms on the same icosahedral five-atom layer.

• 한국해양공학회지
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• 제12권3호통권29호
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• pp.31-41
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• 1998

Single fiber fragmentation technique was used to evaluate the change of interfacial properties by degradation of fiber tensile strength in the fiber reinforced composites. The influences of fiber tensile strength on the interfacial properties have been evaluated by the fragmentation specimens(weak fiber samples) of glass fiber/epoxy resin that was made using the pre-degraded glass fiber in distilled water at $80^{circ}C$ for specified periods. The effects of the immersion time on the interfacial properties in the distilled water at $80^{circ}C$ also have been evaluated by the fragmentation specimens(original fiber samples) of glass fiber/epoxy resin that was made using the received glass fiber. As the result, the tensile strength of glass fiber was decreased with the increasing of the treatment time in the distilled water at $80^{circ}C$ and the interfacial shear strength was independent of the change of the glass fiber strength in the single fiber fragmentation test. But in the durability test using the single fiber fragmentation specimen, interfacial shear strength decreased with the increasing of the immersion time in distilled water ar $80^{circ}C$. And it turned out that the evaluating of interfacial shear strength using original fiber tensile strength was valuable in the durability test for the water environment by the single fiber fragmentation technique.

• 복식
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• 제57권6호
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• pp.145-159
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• 2007

Freed from its traditional confinement to the human body, postmodernism in fashion exposes the defectiveness of body and abstracts from the body under. As the 20th century art put premium on self-expression, the body itself became a powerful medium of expression in fashion. Using 'body' to analyze the clothing form, my study develops a framework by which to classify the fragmentation of the body in fashion. In order to inquire the formative style and aesthetic values expressed in fragmentation of the body in fashion, my study examines subjects from the discourse on the body to the fashion collections of the late 20th and 21st century, The results of the study are as follows. Fragmentation of the body in fashion means the break away from the idealized and standardized body for mass productions. It tends to experiment with extreme exaggeration in form, refusing to subscribe to the traditional values that build on the balance and symmetry of the body. The formative aspects of fragmentation are achieved through body casting, displacement, and deconstruction. The absence of physicality in fashion opposes the sartorial convention and symbolism that results in the discord between signifiant and $signifi{\tilde{e}}$ of clothing. Fashion continues to explore forms and images that transcend the traditional representations of the clothed body. As a type of intimate architecture, fashion always mediates the dialogue between clothes and body, or fashion and figure. My study suggests a framework to analyze fragmentation of the body in fashion, focusing on the relationship between the clothes and body.