• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.169-173
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• 1994

The previously reported cytotoxic metabolites, against the KB cell line, xestoquinone, halenaquinol sulfate and $halenaquinol^{5,6}$ were isolated from the unidentified sponge collected in October 1992, Manado Bay, Sulawesi in Indonesia. Their structure were elucidated by $^1H-,\;^{13}C$-NMR, $^1H-,\;^{13}C$(1 bond) Heteronuclear Multiple Quantum Coherence Spectroscopy$(HMQC)^1$, $^1H-,\;^{13}C$C(2 and 3 bond) Heteronuclear multiple Bond Correlation Spectroscopy$(HMBC)^2$, Electron Impact Mass Spectroscopy(EI ms), Ultraviolet Spectroscopy(UV), and Infrared Spectroscopy(IR)

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.301-305
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• 1995

The cytotoxic metabolites, against the KB cell line, halenaquinone, epispongiatriol and aldisin were isolated from the sponge Spongia sp. collected in September 1992, Manado Bay, Sulawesi in Indonesia. Their structures were elucidated by 1H, 13C NMR, 1H 13C(1 bond) Heteronuclear Multiple Quantum Coherence Spectroscopy (HMQC), 1H 13C(2 and 3 bond) Heteronuclear Multiple Bond Correlation Spectroscopy (HMBC), Electron Impact Mass Spectroscopy (EI ms) and Infrared Spectroscopy (IR).

• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.785-792
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• 2000

Mass spectral fragmentations of six chlorinated organophosphorus pesticides were investigated using electron impact mass spectrometry. Understanding the fragmentation pathways, based on the fragment ions of mass spectra, should be useful in the structural elucidation and chemical identification of these compounds. The pro-posed fragmentation pathways were verified by collision-induced dissociation B/E-linked scan spectra. ln most cases,the structures of characteristic fragment ions could be expected by the observation of the peak clusters due to 35Cl and 37Cl isotopes. According to substituted groups on phosphorus atom, phosphate and phospho-rothioate exhibited significantIy differentfragmentation patterns. Especially, phosphate and phosphorothioate with diethyl ester produced more diverse fragment ions than that with dimethyl ester.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.482-486
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• 1992

Ion-molecule reactions of acetylene and mixed acetylene-ammonia cluster ions are studied using an electron impact time-of-flight mass spectrometer. The present results clearly demonstrate that $(C_2H_2)_n^+$ cluster ion distribution represents a distinct magic number of n=3. The mass spectroscopic evidence for the enhanced structural stabilities of $[C_6H_4{\cdot}(NH_3)_m]^+$ (m=0-8) ions is also found along with the detection of mixed cluster $[(C_2H_2)_n{\cdot}(NH_3)_m]^+$ ions, which gives insight into the feasible structure of solvated ions. This is rationalized on the basis of the structural stability for acetylene clusters and the dissociation dynamics of the complex ion under the presence of solvent molecules.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.340-340
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• 2012

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.1.1-4
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• 1999

The toughening mechanism and fracture behavior of rubber/polymer composites were investigated with respect to two factors; (1) the composition ratio of polymers(PPO and PS which have a different chain flexibility) and (ii) the rubber particle size in PPO/PS blend system Izod impact test and fractographic observation of the fracture surface using scanning electron microscope were conducted, Finite element analysis were carried out to gain understanding of plastic deformation(shear yielding and crazing) of these materials.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1824-1832
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• 1992

This study investigated the compressive Young's modulus and the impactinduced damage of CFRP angle-ply laminate under same impact energy condition. The specimens of angle-ply laminate composites [0.deg.$_{6}$/ .theta..deg.$_{10}$/ 0.deg.$_{6}$] with .theta..deg. =30.deg., 45.deg., 60.deg. and 90.deg. were employed, and damaged by steel balls of diameter of 5mm and 10mm propelled by air gun type impact testing machine. The impact damaged zones were observed through a scanning acoustic microscope(SAM), and their cross-sections were observed through a scanning electron microscope(SEM). The compressive Young's moduli before and after impact were measured, and compared with the theoretical values calculated. The results obtained were as follows: (1) The damage areas on the interfacial boundaries showed more severe change on the back side interface than on the impact side interface with increasing ply-angle. (2) The damage areas on the interfacial boundaries became larger with increasing impact velocity or ply-angle. (3) The impact damaged zone showed the delamination on the interfacial boundaries and transverse cracks inside laminas. (4) The impact damaged zone was affected by the impactor size and speed or ply-angle under same impact energy condition. (5) Compressive Young's moduli before and after impact were lower than theoretical value, but showed a similar change according to ply-angle. (6) Compressive Young's moduli after impact were higher than those before impact, but there was no remarkable change in apparent compressive modulus after impact.t.act.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.129-135
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• 1996

In this paper, the hot carrier effect and device degradation of deep submicrometer SC-PMOSFETs have been measured and characterized. It has been shown that the substrate current of a 0.15$\mu$m PMOSFET increases with increasing of impact ionization rate, and the impact ionization rate is a function of the gate length and gate bias voltage. Correlation between gate current and substrate current is investigated within the general framework of the lucky-electron. It is found that the impact ionization rate increases, but the device degradation is not serious with decreasing effective channel length. SCIHE is suggested as the possible phusical mechanism for enhanced impact ionization rate and gate current reduction. Considering the hot carrier induced device degradation, it has been found that the maximum supply voltage is about -2.6V for 0.15$\mu$m PMOSFET.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.835-842
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• 2002

In this paper, static and fatigue bending strengths and failure mechanisms of CFRP (carbon fiber reinforced plastics) laminates having impact damages have been evaluated. Composite laminates used for this experiment are CF/EPOXY orthotropy laminated plates, which have two-interfaces $[0^0_ 4/90^0_4]_{ sym}$. A steel ball launched by the air gun collides against CFRP laminates to generate impact damages. The damage growth during bending fatigue test is observed by the scanning acoustic microscope (SAM) and also, the fracture surfaces were observed by using the SEM (scanning electron microscope). In the case of impacted-side compression, fracture is propagated from the transverse crack generated near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension. Eventually, failure mechanisms have been confirmed based on the observed delamination areas and fracture surfaces.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.89-92
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• 2001

Drop weight impact tests were performed to investigate the impact behavior of carbon fiber/epoxy composite laminates reinforced by short fibers and other interleaving materials. Characterization techniques, such as cross-sectional fractography and scanning acoustic microscopy, were employed quantitatively to assess the internal damage of some composite laminates. Scanning electron microscopy was used to observe impact damage and fracture modes on specimen fracture surfaces. The results show that composite laminates experience various types of fracture; delamination, intra-ply cracking, matrix cracking and fiber breakage depending on the interlayer materials. Among the composite laminates tested in this study, the composites reinforced by Zylon fibers showed very good impact damage resistance with medium level of damage, while the composites interleaved by poly(ethylene-co-acrylic acid) (PEEA) film is expected to deteriorate the bulk strength due to the reduction of fiber volume fraction, even though the damaged area is significantly reduced.