林土의 有機物의 分解速度와 無機養料의 垂直分布에 關한 考察

金遵敏,張楠基,鄭玩鎬 서울대학교 교육대학원 학술연구회 1966 論文集 - 서울대학교 교육대학원 Vol.3 No.-

Kim Choon Min, Chang Nam Kee and Chung Whan Ho: Decomposition rate of plant residue and the vertical distibution of mineral nutrients in the woodland soil. The relationship between decomposition rate of litter and the amount of mineral nutrients dispersed to the soil horizons were studied on the oak and pine forest stand. The results are as follows: 1. Decomposition rate of litter was highest in the F horizon of the oak stand, however in the pine stand it was highest in H horizon. 2. The correlation coefficients between decomposition rate and humus, organic carbon, moisture content, calcium, phosphorus, and nitrogen in the pine stand are; 0.90, 0.98, 0.76, 0.98, and 0.88, in oak stand; 0.97, 0.93, 0.92, 0.97, 0.74 and 0.73. 3. Factors which affect the decomposition rate of litter are humus, organic carbon, moisture content, calcium, phosphorus and nitrogen. 4. Among the variables, PH, moisture content and phosphorus under the oak and pine forest showed significant differences in each horizon. 5. C/N ratio of pine stands is higher than that of oak stands studied. 6. The vertical distribution of mineral nutrients is highly related with the amount of humus accumulated on top soil.

Site-directed Mutagenesis에 의한 RBP(Ribose Binding Protein)의 #5-Ala의 치환과 rbsB103 복귀 돌연변이의 분리

정환웅,백광희 경희대학교 유전공학연구소 1995 遺傳工學論文集 Vol.7 No.-

Ribose-binding protein (RBP) of E coli function in the periplasm as a component of a high affinity transport system for ribose and as a primary receptor for chemotaxis toward ribose. A mutant (rbsB103) in the signal sequence of RBP has a defect in the export of the protein to the periplasm. The intragenic suppressors for rbsB103 were isolated genetically. One of them had a change at 5th amino acid of RBP. In order to assess the role of the 5th amino acid in the transport of rbsB103, we substituted the alanine of 5th position with various amino acids by site-directed mutagenesis. The mutants replaced by Arg, Asp, Pro, or Ser at 5th amino acid of RBP can suppress the defect of protein transport.

B+트리를 위한 벌크로드

황환규,김상욱 江原大學校 産業技術硏究所 1995 産業技術硏究 Vol.15 No.-

In this paper, we propose a bulk-load algorithm for B' -trees, the most widely used index structures in database systems. The main characteristic of our algorithm is to simultaneously process all the keys to be placed on each B' -tree page when accessing the page. This avoids the overhead for accessing the same page multiple times, which results from applying the B' -tree insertion algorithm repeatedly. For performance evaluation, we analyze our algorithm in terms of the number of disk accesses. The results show that the number of disk accesses excluding those in the redistribution process in identical to the number of B' -tree pages. Considering that the redistribution process is an unavoidable preprocessing step for bulk-loading, our algorithm requires just one disk access per B' -tree page, and therefore turns out to be optimal. We also present performance tendancy according to the changes of parameter values via simulation.

GIS에서의 공간 조인 기법의 관한 고찰

황환규,김상욱 강원대학교 정보통신연구소 1998 정보통신논문지 Vol.2 No.-

The spatial join operation is one of the fundamental spatial database query operations. It facilitates the retrieval of information from two different spatial objects based on spatial relationships. The join is one of the most difficult operations to implement efficiently in spaital database systems, as it was with relational database ststems. In this paper, different kinds of spatial joins and various implementation techniques are surveyed. We investigate the basic idea, algorithms, and performance of the various spatial join techniques. In addiotion, we discuss the issues of the different spatial join techniques.

이동통신서비스시장의 기간통신사업자와 재판매 사업자간의 전략적 가격설정 및 무선접속망을 공유함에 있어서의 이용대가 산정방안

김환선 정보통신정책학회 2004 정보통신정책연구 Vol.11 No.4

본 연구논문은 이동전화서비스시장에 있어서 기간통신사업자와 재판매사업자간 복점경쟁하에서의 전략적 가격설정모델을 제시한다. 즉 두 사업자가 동시에 가격을 전략적으로 변경하는 유한반복게임을 통해 비협조적 게임하에서의 내쉬균형 가격을 유도 한다. 또한 가격과 서비스 품질에 대한 소비자들의 반응을 기반으로 소비자들의 서비스 선택과정을 시뮬레이션으로 구현함으로써 각 사업자의 수요 및 그에 따른 수익의 변화를 예측한다. 그 밖에도 본 연구논문은 두 사업자가 무선접속망, 즉 기지국의 무선채널을 공유하는 경우를 고려하여, 공유하는 무선채널부분에 대한 이용대가를 협상에 의해 산정하는 방안을 제시한다. 무선채널을 공유함으로써 추가수익을 얻는 재판매 사업자가 수익의 손해를 입는 기간통신사업자에게 보상금을 지불함으로써, 궁극적으로 기간통신사업자가 무선채널의 공유를 허용하게끔 유도하는 Win-Win 전략방안이다. 결과적으로 보상금의 형식을 통한 두 사업자간의 수익분배방식은, 무선채널 사용에 대한 대가를 산정함에 있어서 실제 사용한 트래픽량을 측정하여야만 하는 복잡함과 번거로움을 배제하며, 또한 이용대가를 산정하기 위하여 설비치 원가를 분석해야 하는 어려움도 극복할 수 있다는 장점이 있다. This paper models strategic pricing decisions between a common carrier and a reseller in a duopoly market of mobile telecommunication service. The model derives Nash equilibrium prices under the noncooperative and finitely repeated games. This paper observes demand and profit changes of each service provider, by simulating customers' decision-making processes given price and service quality. It also considers a situation in which the two service providers share wireless access channels of a base station and suggests a negotiation-based compensation method for sharing them. By inducing the reseller, who benefits from sharing the channels, to pay a side-payment to the common carrier, who looses from sharing the channels, they reach on an agreement to share the channels, which is a 'win-win' strategy. The profit-sharing mechanism based on the side-payment eliminates the complexity of metering the traffic using the channels and analyzing the relevant facility cost, which are usually required to estimate the cost of sharing the channels.

디지털 경제시대에서의 중소기업 인적자원 개발

김환식 한국직업능력개발원 2001 직업능력개발연구 Vol.4 No.2

In general, the 21C is called the knowledge-based society, which is strengthened by digital economy, characterized as ICT industry, Internet, e-commerce and so on. According to the advent of the digital economy age, SMBs has come to compete with the large enterprises equally. That's because the size, distance and space are not the factor of competitiveness power furthermore. If SMBs have gotten the new and state-of-the-art technology and made strong efforts to innovate, they are capable of competing and sometimes held a prominent position. However, the technology and innovation will be able to realize by human resources. After all, the competitiveness of SMBs will be determined by the recruiting and managing of the competent human resources. The supporting system of the HRD of workers in SMBs is represented as vocational competency development program based on the vocational training promotion act. Usually, the HRD of workers in SMBs is a field of market failure, because of externalities of HRD. To relieve market failure and build up skill development of SMBs workers, the HRD for SMBs workers is treated preferentially as compared with the HRD for SMBs workers under the provision fo the act. However, the actual results were not produced differently to the intention. This is possible not only because of market failure, but also because of government failure. So the program and system have to be renovated and reformed. The direction of HRD for SMBs workers, especially at from the side of governmental supporting system and program, is as follows. The approaches and methods suggested in the paper are not coherent. First, the HRD supporting system for SMBs worker is reviewed and the distinguished regulation between SMBs and large companies is also reviewed whether it is rationalized the digital economy age or not. Second, government (government funded institution) has to help SMBs to make a plan on HRD based on business strategy financially. The employment insurance act has to be revised. Vocational competency development program has to be renovated into fitting social insurances purpose, if the program is linked with the employment insurance continuously. In addition, the program, related to HRD for SMBs workers, working in ministry of education and human resources development and small and medium business administration are also connected with vocational competency development. The national HRD strategies for SMBs workers have to be discussed and established at the ministerial counciil for HRD.

동적 선택률 추정 기법을 위한 오차 분석

황환규,김상욱 강원대학교 정보통신연구소 1997 정보통신논문지 Vol.1 No.-

In this paper, we analyze the errors occurred in a selectivity estimation method based on dynamic maintenance of data distribution, which employs the mulitilevel grid file(MLGF), a multidimensional file structure. We first demonstrate that the estimation errors stem from the uniformity assumption that records are uniformly distributed in their belonging region represented by an entry in a level of an MLGF directory. Based on this demonstration, we then investigate five factors affecting the accuracy of estimation: (1) the data distribution in a region, (2) the number of records stored in an MLGF, (3) the page size, (4) the query region size, and (5) the level of an MLGF directory. Next, we present the tendency of estimation errors according to the change of values for each factor through experiments. The results show that the errors decrease when (1) the distribution of records in a region becomes closer to the uniform one, (2) the number of records in an MLGF increases, (3) the page size decreases, (4) the query region size increases, and (5) the level of an MLGF directory employed as data distribution information becomes lower.

Phenol Novolac 수지 경화제의 연화점 변화에 따른 Epoxy Molding Compound의 물성 변화

김환건 서경대학교 1995 論文集 Vol.23 No.2

반도체를 보호하기 위하여 사용하는 반도체 성형 재료로, 현재 주로 사용되고 있는 Epoxy Molding Compound(EMC)에 경화제로 사용되고 있는 phenol novolac의 특성과 성형 재료의 관계를 조사하기 위하여 phenol novolac resin의 분자량과 깊은 관련이 있는 수지의 연화점 변화에 따른 EMC의 물성 변화를 살펴보았다. 사용된 phenol novolac 수지의 연화점은 각각 83℃, 88℃, 99℃인 3종을 사용하였으며 연화점 변화에 따른 EMC의 물성 변화를 살펴보기 위하여 기계적 물성 특성으로 굽힘 강도와 굽힘 탄성율을, 열적 특성 변화를 관찰하기 위하여 열팽창 계수와 열전도도 그리고 유리 전이온도를 각각 측정하였다. 그리고 성형 특성과의 관계를 살펴보기 위하여 spiral flow를 측정하였고, 전기적 특성으로서 volume resistivity를 측정 비교하였다. 기계적 물성측면에서 보면 탄성율은 연화점이 88℃에서 최소값을 보였으며, 강도는 88℃에서 가장 높은 결과를 나타내었다. 열적특성부문에서 살펴보면 유리 전이온도 이하 영역의 열팽창 계수(a_1)와 유리 전이온도 이상 영역의 열팽창 계수(a_2) 모두 연화점 변화에 따라 큰 변화를 보여주지 못하였다. 또한 유리 전이온도는 연화점 증가에 따라 감소하는 경향을 나타내었으나, 열전도도는 연화점 변화에 따라 변화를 보여주지 못하였다. 성형 특성 측면에서는 관계를 살펴보면 연화점이 88℃인 수지의 경우 spiral flow 가 최대치를 보이며 연화점이 증가함에 따라 더 이상 증가하지 않았다. 이러한 물성으로부터 내부응력을 계산하여 성형물의 특성을 고찰하였다. The physical properties of epoxy molding compound(EMC) according to the change of softening point of phenol novolac resin as hardener have been investigated in order to study the relationship between the properties of phenol novolac resin, which is main hardener of EMC for semiconductor encapsulation, and EMC. The softening points of used phenol novolac resin are 83℃, 88℃, and 99℃, respectively. The flexural strength and flexural modulus as mechanical properties were measured, and thermal expansion coefficient, thermal conductivity and temperature of glass transition(Tg) as thermal properties, spiral flow as moldability, and volume resistivity as electrical properties have been investigated to see the change of physical properties of EMC. The minimum of flexural modulus of EMC was represented at 88℃, and the maximum of flexural strength was done at 88℃. The thermal expansion coefficients in the region below Tg(a_1) and above Tg(a_2) keep constant value according to the change of softening point. Tg decreases with the increase of softening point of phenol novolac resin, but thermal conductivity is not hardly changed with that. It can be found out that spiral flow of EMC does not increases any longer above 88℃. We have considered these system in respect of internal stress.

Lovastatin의 암세포에 대한 항증식 효과에 관한 연구

이환봉,장정순 圓光大學校 醫科學硏究所 1999 圓光醫科學 Vol.15 No.1

Background: Lovastatin which is a potent inhibitor of HMG-CoA reductase has antiproliferative effect on cancer cells. We investigated the cell cycle regulatory mechanism of anti-proliferative effect of lovastatin and its therapeutic value on cancer treatment. Methods: MDA-MB-231, an ER negative breast cancer cell line and PC-3-M, an androgen independent prostate cancer cell line were grown up to use. We checked expression pattern of cell cycle regulatory proteins such as cyclins, cdk inhibitors including p21, cdks, RB and RB family protein p107 with lovastatin by Western blot analysis and immunoprecipitation. Results: The proliferative tendency of breast cancer and prostate cancer cells was decreased with 10 μM lovastatin. Cyclin D1 was decreased, however p21, a cdk inhibitor was increased with lovastatin. There is no change in the protein level of cyclin E, cdk4 and cdk2. After 36 h incubation with lovastatin, RB and p107 were dephosphorylated and showed increased binding with transcription factor E2F1 and E2F4 respectively. Conclusion: These results show that lovastatin has antiproliferative effects on breast and prostate cancer cells. The cell cycle regulatory effects of lovastatin come to G1 phase and those are mediated by cyclin D1 depression, p21 induction and decreased activity of cdk4. In accordance with them RB dephosphorylation and its sucessive binding with E2F1 seem to have important role in growth inhibitory effect of lovastatin. These data suggest that growth inhibitory activity of lovastatin by way of cell cycle regulation supports the therapeutic value for cancer treatment.

CSPAM: 닫힌 빈발 시퀀스 패턴을 위한 효과적인 가지치기 전략

황환규 강원대학교 정보통신연구소 2009 정보통신논문지 Vol.13 No.-

Sequential pattern mining finds all of the frequent sequences satisfying a minimum support threshold in a large database. However, when mining long frequent sequences, or when using very low support thresholds, the performance of currently reported algorithms often degrades dramatically. In this paper we present a novel algorithm, CSPAM (Closed Sequential PAttern Mining), using only closed frequent sequences which are small subset of very large frequent sequences. When systematically exploring the search space of closed frequent sequences, we present two novel pruning strategies, which prune the unpromising parts of search space effectively. The experimental results show that the proposed method outperforms the previous algorithms.