• Toxicological Research
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• v.20 no.4
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• pp.321-324
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• 2004

Lethal dose 50% ($LD_{50}$) has been commonly used as a parameter for the estimation of acute toxicity not only in animal experiment, but also in human study. Several methods to estimate $LD_{50}$ had been introduced, but Spearman-Karber and Berens-Karber method have been widely used due to their relative convenience and accuracy. However, $LD_{50}$ values estimated from the two methods showed inconsistency and variation depending on the characteristics of mortality data. In this study, the two methods were comparatively investigated in terms of accuracy and stability for the estimation of $LD_{50}$.

• ETRI Journal
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• v.4 no.1
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• pp.3-8
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• 1982

성장된 GaInAsP/InP DH wafer로부터 상온에서 duty 5%까지 Pulse 동작이 가능한 전면전극(broad contact) 및 stripe 구조 LD(711이저 다이오드)를 제작하였다. 또 이렇게 제작된 LD의 I-V특성, 1-L 특성 및 발진파장 등을 조사하기 위해 LD 구동회로 및 Ge 태양전지와 Ge-APD를 이용한 광 검출회로를 제작하였다. 이들을 이용해 제작한 LD의 특성을 조사한 결과 stripe 구조 LD인 경우 발진개시전류($I_th$)가 900mA, 발진파장이 $1.29\mum$, 파장반치폭(FWHM)이 $60\AA$였으며 $1.33I_th$까지 kink 없이 동작이 가능하였다.

• Communications of the Korean Mathematical Society
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• v.36 no.1
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• pp.189-196
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• 2021

Using ld-irreducible posets, we can easily characterize posets with respect to linear discrepancy. However, it is difficult to have the list of all the irreducible posets with respect to a given linear discrepancy. In this paper, we investigate some properties of disconnected posets and connected posets with respect to linear discrepancy, respectively and then we find various relationships between ld-irreducibily and connectedness. From these results, we suggest some methods to construct ld-irreducible posets.

• Korean Journal of Optics and Photonics
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• v.9 no.5
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• pp.333-341
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• 1998

The novel integrated device, 1.55 ${\mu}{\textrm}{m}$ DR-LD(distrbuted reflector laser diode) integrated EA-MOD (electro-absorption modulator) as light source, is proposed to improve the device yield and its operational performances. This device can be easily fabricated by the selective MOVPE technique and its fabrication processes are almost the same as the reported 1.55 ${\mu}{\textrm}{m}$ DFB-LD(distributed feedback laser diode) integrated EA-MOD except the asymmetric gratings. The static and dynamic properties are investigated simultaneously by solving the transfer matrix method for light propagation, the time-dependent rate equation for carrier change and schr$\"{o}$dinger equation for QCSE (Quantum-Confined Stark Effect). The performances of the proposed device such as output power, chirp, and extinction ratio are compared with those of DFB-LD integrated EA-MOD. Under 10Gb/s NRZ modulation, we obtain that DR-LD integrated EA-MOD. is 30% higher in output power on the on-state, about 50% lower in chirp, and slightly larger in extinction ratio than DFB-LD integrated EA-MOD.-MOD.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1485-1490
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• 2006

In this study, comparative replicational properties of Hyphantria cunea nucleopolyhedrovirus (HycuNPV) in Lymantria dispar (IPLB-LdElta) and Spodoptera frugiperda (IPLB-Sf21) cell lines were investigated. Our microscopic observations showed that cytopathic effects (CPEs) in LdElta cells appeared 12 h later than those in Sf21 cells. Whereas polyhedral inclusion bodies (PIBs) formed at 48 h postinfection (p.i.) in LdElta cells, it formed at 36 h p.i. in Sf21 cells. Extracellular virus production determined according to the 50% tissue culture infective dose ($TCID_{50}$) method in LdElta cells started about 12 h later when compared with Sf21 cells. Titers of extracellular virus in LdElta and Sf21 cells were calculated as $1.77{\times}10^9$ plaque forming units (PFU)/ml and $5.6{\times}10^9PFU/ml$, respectively, at 72 h p.i. We also showed that viral DNA replication began at 12 h p.i. in both cell lines. Viral protein synthesis was determined by SDS-polyacrylamide gel electrophoresis (PAGE) and polyhedrin synthesis was observed at 12 h p.i. in both cell lines. The results indicate that while the synthesis of macromolecules is 12 h later and production of extracellular virus is almost 3-fold lower in LdElta cells compared with those in Sf21 cells, the LdElta cell line is still a productive cell line for infection of HycuNPV.

• Journal of Microbiology
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• v.41 no.4
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• pp.306-311
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• 2003

In Korea, a Lymantria dispar multinucleocapsid nucleopolyhedrovirus, LdMNPV-NM, was isolated and characterized from dead L. dispar larvae. The polyhedra of LdMNPV-NM were irregularly shaped with a diameter of $1.62{\pm}0.33{\mu}m$. Numerous virions comprised of the multinucleocapsid were evident in the electron microscopic examination of the polyhedra cross sections. These polyhedra were composed of a major protein of 30 kDa. The restriction enzyme digestion patterns of LdMNPV-NM showed that this isolate had some different fragments from those of the Gypchek LdMNPV isolate, although their overall profiles were similar. The deduced amino acid sequence of the enhancin gene of LdMNPV-NM showed differences when compared to previously reported enhancin genes of other LdMNPV strains. These results suggested that the LdMNPV-NM isolate from Korea was a new NPV strain and had a new enhancin gene.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.69
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• pp.85-105
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• 2016

The fact that one of the parties to the sale contract has had to pay demurrage to the shipowner under LD clauses in the charterparty does not of itself mean that he can recover that loss from his sale counter party under the sale contract: the route to such recovery is through express clauses in the sale contract itself. LD clauses in a sale contract stand free and independent of their counterparts in the relevant charterparty. LD clauses in a sale contract should be construed and applied as clauses in sale contracts, not as adjuncts to charterparties. Their interpretation should therefore be coloured not by decisions on laytime and demurrage in charterparties, but by their relationship to the contractual duties of CIF and FOB sellers and buyers. The results discussed here have implications for the drafting of LD clauses in sale contracts. If unwelcome surprises are to be avoided, it seems to advisable to start from the principle: what exactly do traders want or need in LD clauses. They need a clause which covers them against charterparty losses where those losses are the result of dealy caused by the counterparty to the sale contract. The parties to the sale contracts are well advised to prepare LD clauses concentrating on that purpose and bearing in mind the followiing questions. First, should the loading and discharge code in the sale contract appear in traders' or trade associations' standard terms and conditions or should they be left to ad hoc negotiation in contract sheets? Second, should that code be as complete as possible, covering loading or discharge periods or rates, demurrage and despatch, or is it enough for only some of those matters to be covered explicitly, leaving other matters to be governed" as per charterparty"? Third, does the introduction or incorporation of a stipulation for the giving of a notice of readiness make the start of laytime more or less predictable as between seller and buyer? Finally should a loading and discharge code in a sale contract actully be called a "laytime and demmurrage clauses"?

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.312-319
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• 2001

We proposed a B-RWG LD (Buried-ridge waveguide laser diode) having more merits than a conventional RWG-LD. It's ridge width is controlled easily, it has the advantage of being more planar than the RWG-LD and it is possible to control refractive index with growth layer thickness. Before fabricating the device, we designed the optimal device for single mode, high efficiency and high power operation. From theoretical analysis, we have to control the $d_2, d_3$ layer thicknesses for lateral effective index difference, $\Delta_{nL}$ to be higher than critical value, and simultaneously consider the ridge width for single mode and low threshold current operation. As a result, it is possible to make a single mode LD having the ridge width of $6~9{\mu}m$ if the lateral effective index difference was controlled properly. perly.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.41-49
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• 2004

Nonlinear distortion introduced by the optical transmitter using a direct modulation of laser diode(LD) and an indirect modulation of optical modulator can limit considerably the performance of analog optical link system such as subcarrier multiplexing system. In this paper, we have compensated the nonlinear distortion of LD and optical modulator using electrical predistorter. In the case of LD, two-tone experiments using 877.5 MHz and 882.5 MHz have shown reduction of 19 dB in third-order intermodulation product(IMP$_3$). And in the case of optical modulator, we have achieved nearly 21 dB reduction in IMP3 through two-tone experiments using 1.8975 GHz and 1.9025 GHz. The spurious free dynamic ranges of LD and optical modulator are also improved by 5 dB/Hz$^{2}$ 3/ and 7 dB/Hz$^{2}$ 3/, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.481-485
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• 2002

In this study, we fabricated the PBH-LD by meltback method using the LPE. The PBH-LDs are analyzed the leakage current that flows through leakage current path like the p-n diode and p-n-p-n current blocking layer. We observed the variation of threshold current with the leakage width $W_{ι}$. As a consequence, we confirmed that the threshold current became low in the decrease of the leakage width and in the increase of the ratio of specific resistivity of leakage region to active region. We also compared between the calculated threshold current in the absence of leakage region and the measured threshold current in the device. As a result, the ratio of specific resistivity was about 0.5 in the measured LDs, which have the width of a active layer of 1.4${\mu}{\textrm}{m}$ and leakage width of 0.6${\mu}{\textrm}{m}$.