• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.5
• /
• pp.88-98
• /
• 1999

A refractive index modulated (RIM) DFB laser, in which the refractive index of a center region of the upper cladding layer comprising the grating region is different from that of side regions, is proposed to obtain and effective ${\lambda}$/4 phase shift in the center region. Since the coupling coefficient of a center region in a RIM-DFB laser is larger than that of side regions, a RIM-DFB laser has the effect of a distributed coupling coefficient. Simulation results show that RIM-DFB lasers have better operation characteristics - more uniform photon density profile, less SHB effect, and better single mode operation at high injection currents - compared to those of ${\lambda}$/4 phase-shifted DFB lasers and CPM-DFB lasers. In addition, the effect of the center region on the above threshold characteristics of a RIM-DFB laser is investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.04b
• /
• pp.14-16
• /
• 2008

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photocurrent is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. ITO was used as an anode, and Al and LiAl were used as a cathode. A layer thickness of Al and LiAl were 100nm. Obtained built-in voltage is about 1.0V in the Al layer was used as a cathode. The obatined built-in voltage is about 1.6V in the LiAl layer was used as a cathode. The result of built-in voltage is dependent of cathode. We can see that the built-in voltage increase up to 0.4V when the LiAl layer was used as the cathode. These results correspond to the work function of LiAl which is lower than that of Al. As a result, the barrier height for an electron injection from the cathode to the organic layer could be lowered when the LiAl was used as a cathode.

• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.3
• /
• pp.149-154
• /
• 2002

The blood pressure (BP) is regulated by the nervous system and humoral factors, such as renin- angiotensin system, vasopressin and others. In the present study, we examined the central effects of glutamate and GABA on the cardiovascular regulation by injection of these substances into the lateral ventricle and also investigated the relationship between these central effects and the action of angiotensin II (Ang). Male Sprague Dawley rats, $350{\sim}400$ g, were anesthetized with urethane and instrumented with an arterial catheter for direct measurement of BP and heart rate (HR), and an guide cannula in the lateral ventricle for drug injection. A glass microelectode was inserted into the rostral ventrolateral medulla (RVLM) for recording single unit spikes. Barosensitive neurons were identified by changes of single unit spikes in RVLM following intravenous injection of nitroprusside and phenylephrine. The effects of GABA and glutamate injected into the lateral ventricle were studied in single neuronal activity of the RVLM in addition to changes in BP and heart rate, and compared the results before and after treatment with intravenous losartan, nonpeptide Ang II-type 1 receptor antagonist (1 mg/100 g BW). Intracerebroventricular administration of GABA decreased systolic blood pressure (SBP) and HR, but increased the firing rates in the RVLM. However, intracerebroventricular glutamate injection produced effects opposite to GABA. After pretreatment of intravenous losartan, the central effects of GABA on BP and firing rate in the RVLM were significantly attenuated and that of glutamate showed a tendency of attenuation. These results suggested that central GABA and glutamate regulated BP and firing rates in RVLM were inversely related to BP change. The central effects of GABA or glutamate on the autonomic nervous function were modulated by humoral factor, Ang II, by maintaining BP.

• The Korean Journal of Physiology and Pharmacology
• /
• v.12 no.5
• /
• pp.237-243
• /
• 2008

Intraplantar injection of melittin has been known to induce sustained decrease of mechanical threshold and increase of spontaneous flinchings. The present study was undertaken to investigate how the melittin-induced nociceptive responses were modulated by changes of metabotropic glutamate receptor (mGluR) activity. Changes in paw withdrawal threshold (PWT), number of flinchings and paw thickness were measured at a given time point after injection of melittin ($10{\mu}g$/paw) into the mid-plantar area of rat hindpaw. To observe the effects of mGluRs on the melittin-induced nociceptions, group I mGluR (AIDA, $100{\mu}g$ and $200{\mu}g$), $mGluR_1$ (LY367385, $50{\mu}g$ and $100{\mu}g$) and $mGluR_5$ (MPEP, $200{\mu}g$ and $300{\mu}g$) antagonists, group II (APDC, $100{\mu}g$ and $200{\mu}g$) and III (L-SOP, $100{\mu}g$ and $200{\mu}g$) agonists were intrathecally administered 20 min before melittin injection. Intraplantar injection of melittin induced a sustained decrease of mechanical threshold, spontaneous flinchings and edema. The effects of melittin to reduce mechanical threshold and to induce spontaneous flinchings were significantly suppressed following intrathecal pre-administration of group I mGluR, $mGluR_1$ and $mGluR_5$ antagonists, group II and III mGluR agonists. Group I mGluR antagonists and group II and III mGluR agonists had no significant effect on melittin-induced edema. These experimental findings indicate that multiple spinal mGluRs are involved in the modulation of melittin-induced nociceptive responses.

• The Journal of Korean Medicine
• /
• v.24 no.2
• /
• pp.193-203
• /
• 2003

Objectives : In this study, we investigated the effect and pathway of contralateral heterotropic electroacupuncture (EA) on pain induced by fonualin in rats. Methods : Acu-points in the right forepaws, HT 7 and PC 7 were stimulated with 3~4mA, 2ms, and 10Hz after 5% formalin (50ul) s.c. injection to the left hind paw. In addition, it was investigated whether the dorsolateral funiculus (DLF), known to be related the descending inhibition, mediates analgesic effects of the contralateral heterotropic EA or whether administration of naltrexone, an opioid antagonist, blocks the effect of EA. Results : The results showed that contralateral heterotropic electroacupuncture (EA) inhibited late phase (63.311.7%) of pain induced by fonualin in the behavioral test, but sham-EA had little effect on pain behavior (85.616.8%) and no analgesic effects after transection of the dorsolateral funiculus (95.718.7%). The pretreatment of naltrexone (10mg/kg, i.p.) could not inhibit the analgesic effects of EA on formalin-induced pain behavior (70.713.1%). Also,EA suppressed formalin injection induced expression of cFos like protein (cFL) in the dorsal homo but not sham-EA. Suppressed expressions of cFL in the spinal cord were eliminated after transection of the ipsilateral dorsolateral funiculus at T10-11 leve1s. However, pretreatment of naltrexone could not prevent the suppressive expressions of cFL at the spinal cord. Conclusions : These results suggest that the analgesic effect of contralateral heterotropic electroacupuncture may be modulated through the dorsolateral funiculus constituting the descending inhibition.

• The Korean Journal of Physiology and Pharmacology
• /
• v.10 no.1
• /
• pp.45-50
• /
• 2006

Melittin-induced pain model has been known to be very useful for the study of pain mechanism. Melittin-induced nociceptive responses are reported to be modulated by the changes in the activity of excitatory amino acid receptor, calcium channel, spinal serotonin receptor and extracellular signaling-regulated kinase. The present study was undertaken to investigate the role of cyclooxygenase (COX) in the melittin-induced nociception. Changes in mechanical threshold, flinchings and paw thickness were measured before and after intraplantar injection of melittin in the rat hind paw. Also studied were the effects of intraperitonealy administered diclofenac (25 mg & 50 mg/kg), piroxicam (10 mg & 20 mg/kg) and meloxicam (10 mg & 20 mg/kg) on the melittin-induced nociceptions. Intraplantar injection of melittin caused marked reduction of mechanical threshold that was dose-dependently attenuated by non-selective COX inhibitor (diclofenac) and selective COX-1 inhibitor (piroxicam), but not by COX-2 inhibitor (meloxicam). Melittin-induced flinchings were strongly suppressed by non-selective COX and COX-1 inhibitor, but not by COX-2 inhibitor. None of the COX inhibitors had inhibitory effects on melittin-induced increase of paw thickness (edema). These experimental findings suggest that COX-1 plays an important role in the melittin-induced nociceptive responses.

• Biomedical Science Letters
• /
• v.24 no.3
• /
• pp.239-244
• /
• 2018

Recently, many researches regarding the natural products which alternate with chemical products have been done. Among them, boswellia is well known for effect on anti-oxidative effect and inflammation. The aim was the effect boswellia of formalin- induced orofacial and temporomandibular joint (TMJ) pain on experimental animals was investigated. Experiments were carried out using subcutaneous (SC) pain model and TMJ pain model that were induced by the injection of 5% formalin into the right vibrissa pad (SC, $50{\mu}L$) or TMJ ($30{\mu}L$) of rats, respectively. In both models, formalin (5%), formalin after distilled water (vehicle), formalin after boswellia extract (p.o., concentrations of 15, 30 mg/kg) (n=6). The number of scratching on the injected region was scored during the 9 successive periods of 5 min intervals following injection of formalin. Oral administration of boswellia (15, 30 mg / kg) reduced formalin-induced SC orofacial pain behavioral responses. SC orofacial pain behavioral responses was significantly reduced at 20~35 min. In the experimental group injected into temporomandibular joints, the pain response was significantly reduced by $276.2{\pm}8.20$ and $78.3{\pm}4.7$ after oral administration of boswellia (15, 30 mg / kg) at $398.3{\pm}24.8$ times. As a result of the passage of time, the oral administration of boswellia showed a significant effect of reducing the temporomandibular joint pain 30 minutes after the injection of formalin. This study confirmed that oral administration of boswellia modulated the pain behavior in both models. In conclusion, boswellia extract may be a potential therapeutic treatment for orofacial pain.

• Korean Journal of Acupuncture
• /
• v.23 no.3
• /
• pp.55-71
• /
• 2006

Objectives : The present study was investigated the effect and pathway of heterotopic electroacupuncture (EA) on pain induced by formalin in rats. Methods : Acupoints in the right forepaws, $HT_7$ and $PC_7$, were stimulated with 3 mA, 2 ms, and 10 Hz before subcutaneously formalin injection (5%, $50{\mu}l$) to the left hind paw. Moreover, it was investigated whether the dorsolateral funiculus (DLF), as known to the descending inhibition, mediates analgesia of the heterotopic EA, and an administration of naltrexone blocks the effect of EA. Results : In the immunohistochemistry of cFos-like protein (cFL), there were inhibitory effects of EA on the increased expression of cFL in the lumbar spinal dorsal horn neurons following formalin injection. Especially, EA inhibited the expression of cFL on the superficial laminae than that on the deep laminae at 1 hr after, but that on the deep laminae than that on the superficial laminae at 2 hr after. Also, EA suppressed the increased expression of nitric oxide (NO) and neuronal nitric oxide synthase (nNOS) in the lumbosacral spinal cord after formalin injection, but not Sham-EA. Suppressed expressions of cFL, NO and nNOS in the spinal cord were eliminated after transection of the ipsilateral DLF at $T_{10}{\sim}T_{11}$ levels. However, pretreatment of naltrexone could not prevent the suppressive expressions of cFL, NO and nNOS at the spinal cord. Conclusions : These results suggest that the analgesia of heterotopic EA may be modulated through the DLF constituting the descending inhibition.

• The Korean Journal of Physiology and Pharmacology
• /
• v.11 no.5
• /
• pp.215-219
• /
• 2007

Small and large conductance $Ca^{2+}$-activated $K^+(SK_{Ca}\;and\;BK_{Ca})$ channels are implicated in the modulation of neuronal excitability. We investigated how changes in peripheral $K_{Ca}$ channel activity affect mechanical sensitivity as well as the afferent fiber type responsible for $K_{Ca}$ channel-induced mechanical sensitivity. Blockade of $SK_{Ca}$ and $BK_{Ca}$ channels induced a sustained decrease of mechanical threshold which was significantly attenuated by topical application of capsaicin onto afferent fiber and intraplantar injection of 1-ethyl-2-benzimidazolinone. NS1619 selectively attenuated the decrease of mechanical threshold induced by charybdotoxin, but not by apamin. Spontaneous flinching and paw thickness were not significantly different after $K_{Ca}$ channel blockade. These results suggest that mechanical sensitivity can be modulated by $K_{Ca}$ channels on capsaicin-sensitive afferent fibers.

• Korean Journal of Optics and Photonics
• /
• v.11 no.3
• /
• pp.206-209
• /
• 2000

A wavelength stabilized high power CW DFB LD module was designed and fabricated for use in externally modulated, Dense Wavelength Division Multiplex (DWDM) systems. A simple, compact wavelength monitoring technology using a thin solid Etalon and PD array assembly was developed for a low cost wavelength stabilized DFB LD module. Also, the excellent module have high power characteristic of 13.5 mW in CW 100 mA current injection with high optical coupling coefficient over 43%. r 43%.