• Analytical Science and Technology
• /
• v.15 no.4
• /
• pp.335-340
• /
• 2002

An analytical method has been developed to determine multi-elements in human hair samples by inductively coupled plasma mass spectrometry (ICP-MS). 0.05 g of hair sample was added to the Teflon digestion bomb together with 1.5 mL of nitric acid and an appropriate amount of In as an internal standard. The sample was then decomposed in the microwave digestion system. The hair certified reference material, GBW 09101, was analyzed for the validation of the analytical method. The determined values were in good agreement with the certified values within the uncertainty range.

• Korean Journal of Organic Agriculture
• /
• v.9 no.2
• /
• pp.23-37
• /
• 2001

WTO체제에서 국제 경쟁력을 갖추기 위한 전략의 하나로 친환경농업을 추진해온 우리나라 농업은 환경오염의 경감과 농업의 다원적 가치의 실현을 위한 친환경농업 전문가 양성이 시급하며 이를 대학 교육에서 담당할 필요성이 높아지고 있다. 본 연구에서 4개 사례 대학의 교과과정 분석 결과 한국의 농학계 대학에서 이루어지고 있는 환경 교육은 대부분의 대학이 대학의 명칭이나 학과의 명칭을 변경하는 과정에서 생명, 자원, 환경을 포함시키고 교육 목표에서도 환경과 관련된 내용이 제시되고 있으며, 교육과정에 환경오염방지 및 개선에 관계된 과목을 설강하여 학생들에게 수강하도록 하고 있다. 또한 농업의 위치와 사회적 역할로서 농업의 다원적 기능과 농업과 환경에 대한 강의가 일부 대학에서 이루어지고 있으며, 비농업 전공자들에게도 호응을 얻고 있다. 그러나 현재 이루어지고 있는 환경교육은 별도의 농업환경 교육과정이 마련되어 있지 않으며, 설강된 과목들도 연계성이 부족하고, 전공과목 우선으로 수강하게 되므로 그 비중이 매우 적은 실정이다. 따라서 농업환경 교과과정을 별도로 개발하여 학생들로 하여금 체계적인 교육을 받도록 할 필요가 있다. 앞으로 환경분야에 대한 사회적 직업 수요가 증가함에 따라 농학의 수요는 더욱 증가할 것이며 환경평가나 환경계획 관련 분야 및 영농현장이나 관련 기관에 종사할 인력들에게 있어서도 대학에서의 체계적인 교육이 필요하다.

• Sleep Medicine and Psychophysiology
• /
• v.5 no.2
• /
• pp.202-209
• /
• 1998

Authors report the findings of nocturnal polysomnography and multiple sleep latency test(MSLT) before and after morning light treatment in a winter depressive patient with hypersomnia. On polysomnographic recordings, the sleep pattern of this case before light treatment was similar to that of narcolepsy exhibited, sleep onset REM period(SOREMP). After treatment, the shortened REM latency changed to normal condition, but, deep sleep percentage did not changed, and stage 4 sleep percentage was decreased. Depressive symptoms were improved on clinical interview with Hamilton Depressive Rating Scale. Sleep log showed shortened sleep latency and reduced sleep duration. These findings suggest that although light treatment could alter the sleep structure in seasonal affective disorder with hypersomnia, it does not necessarily imply that antidepressant response of light treatment is result of change of sleep structure.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.7
• /
• pp.1659-1666
• /
• 1998

The multicode CDMA systems that are widely studied as an effective transmission methodology in the IMT-2000 systems, employ orthogonal codes to transform high rate data into parallel, low rate data for simultaneous transmission. In this paper, we propose a new multicode CDMA system which achieves the same data rate and processing gain of the conventional systems, while significantly improves bit error rate performance by exploiting a convolutional code with code rate r=1/2 and a bi-orthogonal code. The simulation results for synchronous systems using maximal ratio combining Rake receivers under additive white Gaussian noise and multi-path fading channels, show significant improviements by the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.4
• /
• pp.967-975
• /
• 1998

This paper presents a system to cancel the multi-user interference of synchronous DS/CDMA systems by using the estimation circuit and the reference correlator. In the code-division multiple access(CDMA) scheme, the spectrum of the user's signal is directly spreaded by means of the Simplex coed or the phase offsetted PN code. It is interesting for the Simplex code and the PN code to have a similar correalation property. It these codes are used in DS/CDMA systems, the number of acceptable users can be increased in comparison with conventioal DS/CDMA systems. This thesis presents a interference cancellation model to cancel the multi-use interference in DS/CDMA systems by using Simples code of PN code as a spreading sequence. In AWGN environment, we analyze interference generated from other users and compare the resulting performance with that of the conventioanl receiver in same user side.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.1
• /
• pp.61-72
• /
• 1997

The implementation of base station transceiver for Wideband CDMA(Code Division Multiple Access) PCS(Personal Communication Service) system using spread spectrum CDMA technology is presented in this paper. The receiver that requires wide dynamic range and high sensitivity and the transmitter that has good spurious emission supression were designed and implemented with 5 MHz RF channel bandwidth. This paper shows the some factors that should be considered and simulated using the RF simulation S/W with commercial and customized components. The implemented transceiver based on the simulation gave good results that satisfied the functional specifications of the transceiver.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.7A
• /
• pp.943-950
• /
• 2000

In this paper, an asynchronous multi-rate optical wireless pulse position modulation-code division multiple access (PPM-CDMA) is proposed for an indoor non-directed diffuse channel. As a signature sequence for CDMA, an optical orthogonal code (OOC) is used and an interference cancellation scheme is applied to improve the bit error rate. It is known that the optical PPM-CDMA has advantages due to its power efficiency. Moreover, it provides multi-rate services by varying the modulation level with fixed pulse duration. In the proposed multi-rate PPM-CDMA system with fixed pulse duration, chip rate and sampling time do not change for each transmission rate and this simplifies overall system structure.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.15 no.4
• /
• pp.341-352
• /
• 1990

In this paper, we introduce tree types of switching networks, I, e., a fully segregated type, a partially integrated type, and a fully integrated type switch, to accommodate nx 64Kb/s multi-slot connection traffic and analyze their blocking probabilites for the different traffic mixes by utilizing a computational algorithm of blocking probability, and finally determine the traffic handling capacity which satisfies the given grade of service. The fully integrated type switch can accommodate the ISDN traffic with relatively low wideband traffic. However, either the partially integrated type or the fully segregated type switch is needed to accommodate the ISDN traffic as the wideband traffic increases. This result can be usilized in the design of ISDN switching networks accommodating multi-slot connection traffic.

• Korean Journal of Optics and Photonics
• /
• v.13 no.5
• /
• pp.435-441
• /
• 2002

In this paper, we propose an optimal 2-dimensional construction algorithm of a code family for a high-speed optical code division multiple access network. The optimal 2-D code family generated by search algorithm has better spectrum efficiency than previous codes, having relatively many code sets with short code length and the same or lower BER. Using the optimal 2-D code, OCDMA systems make it possible to utilize the spectrum more efficiently than WDM systems. The probability of bit error for high-speed OCDMA transmissions is calculated as a function of the number of users in the presence of receiver and shot noise(additive white Gaussian noise).

• Journal of Information Technology Services
• /
• v.20 no.5
• /
• pp.105-118
• /
• 2021

As we enter the era of the 4th industrial revolution, information and communication technologies, including artificial intelligence and big data, are converging throughout society. Especially, as the importance of the social foundation of hyper-connection grows, the social influence of IoT, a network of connecting objects, people, and various entities, is also gradually expanding. In addition, as a pandemic, COVID-19, continues, interests in untact-oriented technology and service development are growing more than ever, and each company is trying to establish a core competency strategy to gain an edge in competition in the changing society. This study is a case study centered on Dawon DNS, a company that provides an IoT-based AI smart plug platform. Dawon DNS is broadening its services while developing products by applying advanced technologies, and this study is aiming to investigate the core competencies of the business evolution process. The obtained result of this study will provide implications for companies to become more competitive by suggesting the attitudes and strategies that startups should have during the transforming business environment.