• 한국정보시스템학회지:정보시스템연구
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• 제25권2호
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• pp.131-152
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• 2016

Purpose Mobile phones increase the frequency and speed of communication. The most popular mobile application in Korea is KakaoTalk, one of the mobile instant messenger(MIM) services. Although studying mobile services such as SMS, SNS and SNG suggests drawing upon theories in marketing, consumer behavior, psychology to investigate their personal use, research on MIM is scarce. We designed this paper to fill this gap. More specifically, this study is focused on the relationships among consumers psychological variables related to purchase intention to emoticons in context of MIM. Design/methodology/approach Data was obtained from 310 KakaoTalk users in Korea via questionnaire. The data was analyzed by structural equation modeling in order to verify the relationship between variables in the model. Specifically, this study is designed to examine the structural relationships among perceived benefits, perceived risks, trust in messenger service, system quality, trust in platform, and emoticons purchase intention. Findings The findings of this study are as follow. First, perceived benefits and perceived risks had a significant impact on trust in MIM service(e.g. KakaoTalk). Specifically, while perceived benefits had a positive effect on trust in MIM service, perceived risks had a negative effect on trust in MIM service. Second, trust in messenger service also had a positive impact on system quality. Third, trust in messenger service and system quality had a positive effect on trust in platform(e.g. Kakao platform) directly. Lastly, trust in platform had a positive influence on emoticons purchase intention in KakaoTalk messenger.

• Archives of Pharmacal Research
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• 제19권6호
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• pp.520-528
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• 1996

The involvement of the cyclic AMP (cAMP) effector system in the release of endogenous dopamine and acetylcholine from the rat neostriatum was assessed. Forskolin, an activator of adenylate cyclase, was used to enhance cAMP production, and the consequence of this enhancement on the spontaneous and potassium stimulated release of dopamine and acetylcholine was evaluated. Neostriatal slices were prepared from Fischer 344 rats and after a preincubation period the release of each endogenous neurotransmitter was measured from the same slice preparation. To measure acetylcholine release the slice acetylcholinesterase (AChE) activity was inhibited with physostigmine, but the release from slices with intact AChE activity was also determined (choline, instead of acetylcholine was detected in the medium). Under both conditions forskolin induced a significant dose-dependent increase in the potassium-evoked release of dopamine. In the same tissue preparations the release of neither acetylcholine (AChE inhibited) nor choline (AChE intact) was affected by forskolin. The results indicate that the CAMP second messenger system might be involved in neuronal mechanisms that enhance neostriatal dopamine release, but stimulation of this second messenger by forskolin does not further enhance neostriatal acetylcholine release.

• 디지털산업정보학회논문지
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• 제11권3호
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• pp.159-177
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• 2015

As smart phones become more common nowadays, mobile instant messengers such as kakao talk and line are used as essential communication tools exchanging information between individuals. Also, the mobile instant messengers extend their use to business area beyond communication between individuals. This study is on how factors of mobile instant messenger such as perceived security, perceived privacy, perceived enjoyment and perceived interactivity affect business continual usage intention through perceived usefulness. The proposed model is based on Expectation-Confirmation Theory of Oliver and Technology Acceptance Mode of Bhattacherjee. For an analysis, 159 survey responses were collected from the office workers in Seoul and nearby cities, having experiences of mobile instant messengers. To validate the proposed research model, PLS analysis is performed with the valid 154 questionnaires. The path analysis results are as follows. First, perceived security has a positive effect on expectation-confirmation. Second, perceived enjoyment has a positive effect on perceived usefulness. Third, perceived interactivity has a positive effect on both perceived usefulness and expectation-confirmation. Fourth, perceived usefulness has a positive usefulness on satisfaction and continual usage intention of mobile instant messenger. Last, expectation-confirmation has a positive effect on perceived usefulness, and satisfaction has a positive effect on continual usage intention of mobile instant messenger. Since the mobile instant messenger may bring a pressure of work and a violation of privacy, it is necessary that the company provide a guideline for use of the mobile instant messenger and establish the in-house mobile instant messenger system.

• 융합보안논문지
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• 제14권6_2호
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• pp.53-62
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• 2014

이 연구의 목표는 다양한 사회적 문제를 양산하고 있는 현재의 불법행위 흥신소 및 심부름센터의 선진화 방안에 대한 고찰이다. 연구결과는 다음과 같다. 첫째, 관련업종의 불법적 위법 행위룰 방지하기 위해 유사 업종인 산업근거법인 경비업법 적용의 고려이다. 둘째, 해당업종 종사자에 대한 전문자격제도의 도입이다. 셋째, 흥신소 및 심부름센터와 같은 기존의 직업군을 새로운 직업군으로 창출하여 양성화하는 것이다. 넷째, 관할감독기관 선정과 엄격한 관리 감독이다.

• 한국가금학회지
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• 제23권3호
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• pp.113-119
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• 1996

A series of experiments were conducted to investigate the role of protein kinase C (PKC) as a second messenger in vasoactive intestinal peptide (VIP) mediated prolactin secretion. Primary pituitary cells (106 cells/treatment) were separated from laying hens and incubated in M-199 with 5% chicken serum and 5% fetal calf serum. The VIP(0.1 $\pi$M) treatment enhanced prolactin Secretion into media upto 9-fold during 48-h incubation. The phorbol 12-myristate 13-acetate (PMA), a PKG agonist, increased prolactin secretion upto 2-fold at 0.1 nM PMA (P<0.01), and the prolactin secretion was not significantly higher than this concentration. Staurosporine (ST; 1.0$\pi$M) a PKC antagonist, decreased by 70% of 0.1 $\pi$M VIP-stimulated prolactin secretion and by 48% of 10 ${\mu}$M PMA-stimulated prolactin secretion (P<0.01). However, pituitary cell prolactin content did not differ in any treatment (P>0.05). In conclusion, these results indicate that the PKC second messenger system is involved in VIP-stimulated prolactin release in chicken primary pituitary cell culture.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1996년도 춘계학술대회
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• pp.179-179
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• 1996

The involvement of the cyclic AMP (cAMP) effector system in the release of endogenous dopamine and acetylcholine from the rat neostriatum was assessed. Forskolin, an activator of adenylate cyclase, was used to enhance CAMP production, and the consequence of this enhancement on the spontaneous and potassium stimulated release of dopamine and acetylcholine was evaluated. Neostriatal slices were prepared from Fischer 344 rats and after a preincubation period the release of each endogenous neurotransmitter was measured from the same slice preparation. To measure acetylcholine release the slice acetylcholinesterase (AChE) activity was inhibited with physostigmine, but the release from slices with intact AChE activity was also determined (choline, instead of acetylcholine was detected in the medium). Under both conditions forskolin induced a significant dose-dependent increase in the potassium-evoked release of dopamine. In the same tissue preparations the release of neither acetylcholine (AChE inhibited) nor choline (AChE intact) was affected by forskolin. The results indicate that the cAMP second messenger system is involved ill neuronal mechanisms that enhance neuronal dopamine release, but stimulation of this second messenger by forskolin does not further enhance neostriatal acetylcholine release.

• 대한약리학회지
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• 제31권1호
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• pp.11-15
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• 1995

연수의 세로토닌 신경계는 내재성 하행성 동통 억제계 (endogenous descending pain inhibitory system) 에 있어서 중추적인 역할을 하고 있다. 연수의 세로토닌 신경세포에 대한 cholecystokinin (CCK) 및 second messenger systems에 작용하는 약물들의 작용을 알아보기 위하여, 쥐의 태자 (태생 14일) 로부터 연수를 분리하여 10동안 배양한 후 5-hydroxytryptamine (5-HT)의 분비에 대한 cholecystokinin (CCK) 및 second messenger systems에 작용하는 약물의 영향을 연구하였다. 배양 10일된 세포에 여러 neuropeptide들을 $10{\mu}M$ 농도로 48 시간동안 자극한 결과, CCK 와 substance P에 의하여 5-HT의 분비가 증가됨을 관찰하였다. Somatostatin, proctolin, thyrotropin releasing hormone, 및 interleukin-6 은 5-HT의 분비에 있어서 아무런 영향이 없었다. 어떠한 second messenger가 CCK에 의한 5-HT 분비에 연관되어 있나를 알아보기 위하여 calcium channel 봉쇄제인 nimodipine, 그리고 calmodulin 길항제인 calmidazolium의 영향을 살펴본 결과 nimodipine ($1{\mu}M$)은 거의 완전하게, 그리고 calmidazolium ($1{\mu}M$)은 부분적으로 유의하게 CCK에 의한 5-HT의 분비를 억제하였다. 또한 adenyl cyclase의 활성도를 높이는 forskolin ($5{\mu}M$)은 5-HT의 분비를 증가시켰지만 protein kinase C(PKC)를 활성화시키는 phorbol myristate acetate (PMA)는 $2{\mu}M$ 농도에서 5-HT의 분비에 아무런 영향을 미치지 아니하였다. 이상의 연구결과, calcium channel을 통한 calcium influx와 세포내 calmodulin이 CCK에 의한 5-HT분비 증가에 있어서 중요한 역할을 함을 제시한다. 또한, 5-HT의 분비에 있어서 cyclic AMP system이 중요한 역할을 하나, PKC system은 5-HT의 분비에 연관이 없음을 제시하고 있다.

• 한국동물학회지
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• 제37권1호
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• pp.130-136
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• 1994

Although alteration in protein phosphorylation by specific protein kinases is of importance in transducing cellular signals in a variety of neural/endocrine systems, little is known about protein phosphorylation in the hvpothalamus. The present study aims to explore whether activation of the second messenger-dependent protein kinases affects phosphorylation of specific proteins using a cell free phosphorylation system followed by SDS-polvacrylamide gel electrophoresis. Cytoplasmic fractions derived from hvpothalami of immature rats were used as substrates and several activators and/or inhibitors of CAMP-, phosphatidylinositol- and Ca2+-calmodulin-dependent protein kinases were assessed. Many endogenous proteins were extensively phosphorylated and depending on the signal transduction pathways, phosphorvlation profiles were markedly different. The present data indicate that extracellular signals may affect cellular events through protein phosphorylation by second messengers-protein kinases in the rat hypothalamus.

• 약학회지
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• 제44권1호
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• pp.52-59
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• 2000

An exceptionally conserved sequence that is shared among most G protein-coupled neurotransmitter receptors is an aspartate-arginine-tyrosine triplet that is located at the second cytoplasmic domain. Using the ml subtype of muscarinic acetylcholine receptors as an example, a point mutation of the arginine residue at position 123 into asparagine was induced. This mutation resulted in a complete blockade of the carbachol-induced increases of PI hydrolysis and intracellular $Ca^2$$^{+}$ level, in spite of the expression of the wild-type and mutant receptors at similar concentrations in Chinese hamster ovary cells. In marked contrast, the muscarinic agonist carbachol induced concentration-dependent enhancement of the activity of NO synthase at mutant ml receptors although the enhancement was significantly smaller than at wild-type ml receptors. These data suggest that this highly conserved arginine residue plays an important role in coupling of muscarinic receptors to the second messenger systems and the presence of alternate mechanisms of activation of neuronal NO synthase which might be operative in the absence of large changes in the concentration of cellular $Ca^{2+}$.2+/.

• Biomolecules & Therapeutics
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• 제7권4호
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• pp.307-314
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• 1999

The human muscarinic acetylcholine receptor (mAChR) subtypes Hml, Hm2 and Hm3 have been expressed in insect cells (Spodoptera frugiperda, Sf9) using the baculovirus expression system. Expression of relevant DNA, transcript and receptor proteins was identified by PCR, Northern blotting and [$^{3}H$]QNB binding, respectively. As assessed by [$^{3}H$]QNB binding sites, yields of muscarinic receptors in membrane preparations in this study were as about 5-20 times high as those in mammalian cells reported in previous studies. The [$^{3}H$]QNB competition binding studies with well-known subtype-selective mAChR antagonists showed that the receptors expressed in Sf9 cells retain the pharmacological characteristics expected for the ml , m2 and m3 muscarinic receptors. The ml-selective antagonist, pirenzepine, displayed a considerably higher affinity for Hml by 110-fold and 35-fold than for Hm2 and Hm3, respectively, The m2-selective methoctramine displayed a significantly higher affinity for Hm2 than for Hml and Hm3 (10- and 26-fold, respectively). p-F-HHSiD exhibited high affinity for Hm3 that is not significantly different from those for Hml, but 66-fold higher than its affinity for Hm2. The functional coupling of the recombinant receptors to second messenger systems was also examined. While both Hml and Hm3 stimulated phosphoinositide hydrolysis upon activation by carba-chol, Hm2 produced no response. On the other hand, activation of mAChRs induced the inhibition of forsko-lin-stimulated cyclic AMP formation in Hm2-expressing cells, whereas the significant dose-dependent increase in or poor response on cyclic AMP formation were produced in Hml or Hm3-expressing cells, respectively. These results indicate the differential coupling of recombinant Hml, Hm2 and Hm3 receptors expressed in SF9 cells to intracellular signalling system.